The Obligatory Disclaimer

In the course of the day to day working with the accelerator there is a bewildering array of "Accelerator Technospeak" used in the Operations Group and other areas of the Accelerator Division. This glossary is meant to be an attempt at helping the uninitiated understand some of the terms and buzz words that are commonly used in everyday communication within the accelerator group and the lab in general.

Since this glossary was created primarily for Operations Department personnel there are some terms included in this glossary that might be confusing or unfamiliar to those outside of the Operations Department. By the same token there are many commonly understood terms used by other Divisions and groups in the lab that are not well known or non existent within the Operations Department. Many terms will not be found within this document. I have included all terms that I have come across or have been submitted for inclusion. I have also included some definitions of obsolete terms and devices since they still exist in accelerator literature and documentation that is internal to the lab.

Although I have attempted to check all of the entries for accuracy there is no guarantee that all of the definitions are accurate or even current. Entries that come from a Rookie Book or other source are referenced. It is hoped that this glossary will be periodically updated with new material. If anybody has any contributions of terms, definitions or sources of other glossaries to be included please feel free to pass them on, even if they are not related to the accelerator division.

I am grateful for the help of Tony Jackson in helping me research and enter terms until we were both sick of it, John Reyna for supplying an extremely long list of suggestions, Dr. Malensek of the Research Division for allowing me to use his glossary of High Energy Physics Terms, Cons Gatusso for typing skills, and the entire Accelerator Division Operations Department for their suggestions and checking the accuracy of my definitions. I would also like to thank my supervisor Bob Mau for allowing me to spend the enormous amount of time that is necessary for a project of this size.

Sources of terms and definitions from other Laboratory Divisions will be greatly appreciated. Any comments, compliments or complaints are more than welcome.

 			     Original authoring done by:

                                   Jack Standeven
                                Accelerator Division
                                  Operations Group

-Numbers-

080 Module :

The interface module between a microprocessor and its associated CAMAC crate. The microprocessors, such as the Refrigerators, QPM's, and HOG's, use one parallel bus (Multibus) whereas the CAMAC Dataway is a different parallel bus.

130 Module :

An interface module between a console PDP-11/34 and the user-controlled devices at an ACNET console. These modules function as video generators as well as supporting the keyboard, knob, and interrupt button. At this date most of the consoles have been switched over to the new mvax hardware. Eventually all PDP-11 consoles will be phased out and the 130 card will become obsolete.

160 Module :

A card which is capable of generating a ramp waveform which may be a function of time and/or a function of a front panel scale factor, I. This front panel scale factor is generally MDAT but may be any 12 bit digital word. The output of the card is of the form

                   { ( V out ) = I * ( V(I) + G(T) ) }

where V(I) and G(T) are functions of current and time. The card was designed to be used for the Tevatron dipole correction elements. In this usage the output tracks the Tevatron magnet current as represented by the MDAT signal and may contain a "time-bump" which changes the dipole current with respect to the time in the accelerator cycle. These cards are also used for Tevatron RF curves, flying wires, abort kicker waveforms, and some injection magnet waveforms.

165 Module :

A power supply controller for many devices. 165s are used almost exclusivly for time dependant applications. The ramps are loaded from the MCR. The ramp is of the form: { V out = Scale factor * table value * ring energy } The scale factor is set by the D/A value entered by an operator on a parameter page. The table value is a time dependent multiplier set from a 165 control page. The beam energy is represented by MDAT and defaults to full scale if not specified.

175 Module :

Encoder for TCLK. This module generates an eight bit parallel signal, known as a "clock event". This is then shipped to the TCLK transmitter, ( a 176 module ) via a front panel ribbon connector, where it is converted to a serial format and superimposed onto a 10 Mhz signal for transmission. Each 175 module contains 16 prioritized channels. The event is generated whenever a channel receives an external trigger.

177 Module :

A time delay module for many devices around the accelerator. Each module has 8 channels which may be triggered independently, and each may be referenced to as many as 15 TCLK events. Each channel has a programmable delay ranging from 1 microsecond to 65.535 seconds. Upon receipt of a trigger each channel that is enabled outputs a TTL pulse which may be used to trigger any other device.

190 Module :

A module which interface the MADC's around the accelerator to the controls system. It can support up to 128 channels, and is capable of supporting up to 6 plots at a 2.1 Khz rate or a single channel at 70 Khz. It is able to determine which of the devices under its care are in an alarm state, and can decode events on the accelerator clock system.

200 Module :

See abort concentrator module.

279 Module :

A module which provides a programmable delay from a TCLK, MRBS, or TVBS event. The passage of time is measured directly in terms of the number of beam revolutions. A clock "tick" represents 7 RF cycles, so there are 159 ticks per revolution. The clock operates at approximately 7.5 Mhz and is capable of delaying a signal up to 412 turns.

4616 :

Linac RF driver PA tube, with an output of 200 kW. Cathode driver for the 7835 PA tube. Manufactured by RCA.

613 :

Obsolete term. Refered to the Tektronix 613 storage scope that was associated with each ACNET console. It was capable of plotting up to four parameters at a time and retained the image on the screen. 613 also refered to the CAMAC controller card for the storage scope.

7651 :

Linac IPA2 tube, with an output of 2 kW. Drives 4616 driver tube. Manufactured by RCA.

7835 :

Linac PA tube, with an output of 4 MW. Drives linac RF cavity via 9" coaxial transmission line. Manufactured by RCA. 8-Gev MAC : Obsolete device. MAC-16 computer which served as the interface between MR DEC and the 8-Gev devices. It was located in the MAC room. Its functions have been replaced by DEC S.

-A-

A/D , ADC :

Analog to Digital converter (hardware) or the Analog readback of a device (software). The hardware is a device which converts an analog voltage presented at its input to a binary digital representation of that voltage for use by the control system. Most A/D's in the control system have a measurement resolution of less than 5 mv and accept input voltages in the range -10.23 to 10.24 volts. In some applications (Linac and MRPS regulation) special units are used which have a resolution of less than 1.25 mv.

AAL :

Activation Analysis Laboratory of the ES&H Section

Abort :

Terminating the acceleration process prematurely, either by inhibiting the injection mechanism or by removing circulating beam to some sort of dump. This is generally done to prevent injury to some personnel or damage to accelerator components.

Abort Concentrator Module :

A CAMAC 200 module in the Main Ring, Tevatron, and Pbar abort system capable of accepting up to 8 inputs from devices in a given service building. If the permit signal originating from a device disappears, an abort is generated.

Abort Link Generator Module :

A C201 card located at the C0 Service Building which generates the 5 MHz permit signal broadcast around the abort loop.

Abort Logic/Pulse Shifter Interface :

Produces status of Main Ring and Tevatron abort loops. Inputs to Linac Keyswitch Module.

Abort Loop :

The system of electronics which decides to remove the beam from an accelerator in order to protect personnel and/or equipment.

Abort Reset Command (Tev) :

A command sent from the MCR in the form of a TCLK event which clears the latched abort status and restores a beam permit.

Abort System :

The Main Ring and Tevatron abort system at Fermilab is designed to dump the beam promptly on a beam dump. During Fixed Target operation both dumps are located near the long straight section C. During Colliding Beams operation the Tevatron abort system is located in the A0 section of the ring to make room for the Tevatron seperators. The abort magnets are triggered by any one of several abnormal accelerator conditions or radiation alarms. It is routinely fired at the end of an acceleration cycle to purge the accelerator of unextracted beam.

Absolute Pressure :

Units to measure gas pressure. Normally referred to as psia (pounds per square inch absolute) with zero being a perfect vacuum.

Accelerating Column :

Located in the Pre-Acc pit. Set of seven titanium electrodes (eight gaps) arranged in Pierce geometry to accelerate ions to 750 keV. Situated between -750 kV dome and pit wall.

Accelerator :

Any machine used to impart large kinetic energies to charged particles such as electrons, protons, and atomic nuclei. These accelerated particles are then used to probe nuclear or subnuclear phenomena. There are also many accelerators in industrial and medical applications.

Accelerator Studies :

Mode of operation of the accelerator where accelerator performance and/or beam dynamics is studied and tested.

Acceptance :

The measure of the limiting aperture of a transport line, accelerator, or individual device; it defines how "large" a beam will fit without scraping. More technicaly acceptance is the phase-space volume within which the beam must lie in order to be transmitted through an optical system without losses. From an experimenters point of view acceptance is the phase-space volume intercepted by an experimenter's detector system. The complement of emittance.

Accidental Rate :

The rate of false coincidences in an electronic counter experiment produced by products of the reactions of more than one beam particle within the time resolution of the apparatus.

Accumulator:

The storage ring in which successive pulses of antiprotons are collected in order to create an antiproton beam of reasonable intensity for colliding beams physics. The Accumulator is designed to accept a pulse of antiprotons from the Debuncher every few seconds and accumulate up to 5 X 1011 antiprotons in several hours. Some of the design parameters are:

Ring Parameters

• kinetic energy 7.9 GeV
• average radius 75.45 meters
• momentum aperture Dp/p 2.5%
• btron acceptance 10p mm-mrad
• btron tunes, nH 6.611
• nv 8.611
• periodicity 3

  Stack Parameters at Injection

• number of p-'s 8X107
• Dp/p 0.2%
• emittance (both planes) <10p mm-mrad
• fraction of beam accepted >85% of injected pulse

  Final Stack Parameters

• number of p-'s 5X1011
• Dp/p 0.05%
• emittance (both planes) 2p mm-mrad
• peak density 1X105 eV-1
• core width 1.7 MeV (rms)
• total stacking time 5 hours

Achromatic :

The quality of a transport line or optical system where particle momentum has no effect on its trajectory through the system. An achromatic device or system is that in which the output beam displacement or divergence (or both) is independent of the input beam's momentum. If a system of lenses is achromatic, all particles of the same momentum will have equal path lengths through the system.

ACLKWATCHER :

A process on the VAX which decodes TCLK events and generates timing information for internal consumption (for such things as the frequency of data acquisition.)

ACNET :

Accelerator Control NETwork. A system of computers that monitors and controls the accelerator complex. Interfaced to users through consoles in the MCR and elsewhere.

ACNET CONSOLE USER'S GUIDE :

See Console User's Guide.

AD :

Accelerator Division

AD/OPS :

Accelerator Division Operations Department

Adiabatic :

No heat transfer with the environment.

Adiabatic Cooling :

The classical description is a process in which the temperature of a system is reduced without any heat being exchanged between the system and its surroundings. At Fermilab this term is used to describe the process in the Antiproton Source Accumulator storage ring where beam emittances are reduced without affecting beam energy. This process is used in accumulating antiprotons.

Adsorber :

Attracts and holds (by Van der Waal forces) molecular layers of dense gases (i.e. very near condensation temperatures) on porous high surface/volume ratio materials.

Adsorbent :

The material of an adsorber. Silica gel, Alumina, Charcoal. Characterized by high surface/volume ratio.

AEOLUS :

A process on the VAX which collects alarm information from the front-ends, combines that information with appropriate parameters in the database, and sends the package to the console cpus.

Aggregate ON/OFF :

A command used to control the digital status of a block of devices.

AGS :

Alternating Gradient Synchrotron accelerator at Brookhaven National Laboratory on Long Island, New York. It is a 30 GeV combined function proton synchrotron which started operation in 1959.

Air Ionization Chamber :

Devices used by NTF to monitor neutron flux during patient treatment.

ALARA :

As Low As Reasonably Achievable. A safety acronym used to describe the radiation safety philosophy of minimizing occupational radiation exposure.

Alarm :

A message, usually generated by the AEOLUS VAX process, indicating that the digital or analog status of a device is not within the tolerances set for it.

Alarm Display Monitor :

A color television display in the upper right-hand corner of each ACNET console which lists devices currently in a state of alarm.

Alarm screen :

Same as the Alarm Display Monitor (see above)

Alarm system :

The integrated system through which alarms reach the Alarm Display Screen from devices in the field. The front- ends each have their own way of generating alarm codes, which are then forwarded to the AEOLUS process in the VAX. AEOLUS in turn obtains information from the database before sending the combined package to the console cpu. Finally, the Alarm Display Task, a secondary applications program, puts the messages on the alarm screen.

Alpha Function :

( ax, ay ) A measure of the change of the beta function db/dz; a>0 N converging, a Alpha Particle :

A Helium nucleus consisting of two protons and two neutrons, generally seen as a decay product from a heavy radioactive nucleus.

Amplifier :

Any device that amplifies an electronic signal.

Amplitude Control Module :

Linac low-level RF system component that controls the amplitude of the RF gradient by varying the size of the modulator input pulse.

Analog :

Typically a device or circuit that expresses a signal in direct proportion to a physical measurement.

Analog-To-Digital-Converter :

See A/D , ADC

Annihilation :

A process in which a particle and its anti- particle meet and convert spontaneously into photons. It is the inverse of pair production.

Annunciator Board :

Status panel in Linac primary and secondary microprocessors showing status and interrupt levels.

Anode :

Negative electrode or plate of an amplifier tube or discharge tube. In terms of the accelerator it is also taken to mean the power supply cubicles for Booster, Tevatron and Main Ring that contain the transformers for the RF PA anode supplies.

ANSI :

American National Standards Institute

Antiparticle :

A particle having the same mass as a given fundamental particle, but whose other properties, while having the same magnitude, may be of opposite sign, e.g., electrical charge in the case of the electron and positron, magnetic moment in the case of the neutron and antineutron. On collision a particle and its antiparticle may mutually annihilate with the emission of radiation.

Antiparticles :

Each particle has a partner called an antiparticle. Some properties of the antiparticle will be identical in magnitude but opposite in sign to the particle it is paired with. Examples of such properties are electric charge in the case of the electron and positron, and magnetic moment inthe case of the neutron and antineutron. Strangeness and charm are two other properties among many that can vary in sign. When a particle or its antiparticle meet, these properties cancel out in a process called annihilation. The annihilation process between protons and antiprotons are the collisions that take place in the middle of the Tevatron particle detector experiments during colliding beams.

Antiprotons :

Antiparticle to the proton. It is a strongly interacting baryon carrying unit negative charge. It has mass of 938 mev and carries spin 1/2.

Antiquench :

The false appearance of a positive resistive voltage (negative resistance). This is the result of the Quench Protection Monitors's calculation during an actual quench in another cell or due to an instrumentation failure.

AP or APCR :

Antiproton Control Room, located in AP10. Now more commonly referred to simply as AP10.

AP0 :

Accelerator building situated above the pbar target vault enclosure. The power supplies, electronics and maintenance equipment for the pbar target station and lithium lens are located here.

AP1,2,3 :

The beamlines which transport protons and antiprotons between the Main Ring and the Antiproton Source. AP1 serves a dual purpose: First, it transports 120 GeV protons from the Main Ring to the p- production target. Secondly, it transports 8 GeV antiprotons from the AP3 line to the Main Ring (reverse injection). The AP2 line is designed to transport 8 GeV antiprotons from the target vault to the debuncher ring. AP3 exists to transport extracted bunches of p-'s from the Accumulator around the target vault and to ap1, which ultimately brings antiprotons into the Main Ring.

AP4 :

The beamline designed to provide a low intensity beam of 8 GeV protons from the Booster to the Debuncher.

Aperture :

A measure of the physical space available for beam to occupy in a device. Aperture limitations, however, are not always due to the physical size of the vacuum chamber; for instance, a magnetic field anomaly may deflect the beam so that the full available aperture cannot be used.

Aperture scan :

Process of changing the beam position via 3- bumps in a localized area in order to determine the size of the aperture. The beam is moved until is scrapes the side of the beam pipe or encounters an obstruction.

APM :

Applications Program Manager. A function on the console computer which coordinates application task scheduling by making sure the PA or SA executes at the proper periodic rate, recognizes the keyboard interrupt, etc. It also performs console data collection tasks, determines the visible cursor position, shaft encoder position, touch panel x,y position, and the status of the interrupt button.

Apparent Mean Thermal Conductivity :

The effective thermal conductivity of an assemblage of material (Pearlite, super insulation) between specified temperatures.

Application Programs :

Software designed for direct use by a console user. The programs reside on the ACNET consoles.

Archive :

Permanent storage of information regarding a given accelerator system . Magnetic tape is the primary medium. An archive should be distinguished from a "Save", where information is written onto a disk and is likely to be written over at some future date.

ARF1,2,3 :

There are three different radio frequency systems used in the Accumulator and are known as ARF1, 2, and 3. Briefly, ARF1 is a 53 MHz system (h=84) and is used to capture the unbunched beam injected from the Debuncher, decelerate it across the aperture through which the shutter moves, and adiabatically unbunch the beam at the edge of the stack-tail. It is also used to rebunch the unstacked pbars immediately before they are extracted so that the p-'s injected into the Main Ring enjoy a synchronous bucket to bucket transfer. ARF2 is the h=2 system employed to adiabatically capture a portion of the core and accelerate it to the extraction orbit. ARF2 has one suppressed bucket, so only one bunch is unstacked at a time. Since the single bunch is too large longitudinally to fit into the 10-12 MR-size bunches that are wanted, additional RF is energized to shorten up the bunch. ARF3 provides this extra RF. Because it is desirous to perturb the remaining beam in the stack as little as possible, ARF3 is not energized until the beam is on the extraction orbit. Just before the p-'s are extracted, ARF1 is turned on in order to rebunch the beam into 10-11 bunches suitable for synchronous transfer to the Main Ring.

ARGUS :

A process on the VAX which logs off interactive users if the account has been idle for a certain length of time.

ASME :

American Society of Mechanical Engineers

Atmosphere :

A convenient measure of pressure. 1 std atm = 14.696 psia.

Atom :

A particle of matter indivisible by chemical means. It is the fundamental building block of the chemical elements. The elements, such as iron, lead, and sulfur, differ from each other because they contain different kinds of atoms. There are about six sextillion atoms in an ordinary drop of water. According to present day theory, an atom contains a dense inner core (the nucleus) and a much less dense outer domain consisting of electrons in motion around the nucleus. Atoms are electrically neutral.

Atomic % :

A way of describing mixtures, especially of NeH2. Nearly equal to the volume percent.

						  Mole % Ne 
                                    Atomic % Ne = ########### 
                                                  2-Mole % Ne 

For NeH2 only Mole % Ne is higher than Atomic % Ne.

Auto-Gradient :

Feature where the Linac RF gradients are controlled by computer through the Amplitude Control Module. Normally engaged.

Auto Quench Recovery (AQR) :

A computer program residing in the refrigerator micro-p which automatically performs cooldown after a quench.

AUXNETPROCESS :

A process on the VAX which handles routine functions such as the time of day and boot capability for the ACNET network.

-B-

B0 :

A reference point on the Main Ring at which the Collider Detector at Fermilab is located (pronounced "B zero"). Other significant reference points include the D0 collision region, and C0, E0, and F0 regions used for specialized experiments.

B0 Collision Hall :

Also referred to as the Collision Hall. CDF detector at BO resides in this hall during collider operation.

B Clock :

Obsolete. A frequency that was transmitted to a module in the MAC-A PDC crate which was proportional to the change in the Main Ring current. The dI/dT was measured in the magnet cage and transmitted over the Main Ring B-clock link via CC42 cards.

BAO :

Batavia Area Office of the DOE

Back Racks :

Electronics racks behind the primary working region of the Main Control Room; consists of patch panels, link modules, highpotters, and much more.

Background :

Whatever devices are used to make a measurement in an experiment, the measurement is a superposition of events from the target and events from all other sources (background). The background therefore sets a lower limit on the detection of small signals. More generally, background is any unwanted signal.

Bakeout :

To minimize beam loss due to gas scattering, the vacuum within a beam chamber must be as good as possible. The Accumulator is designed to be a high class storage ring capable of circulating the same antiproton beam for hours or days on end. In order to meet the design vacuum of 3x10-10 Torr in the Accumulator provisions have been made to literally bake the Accumulator beam pipe in situ. This causes water vapor, oils, and other contaminants trapped inside the stainless steel to outgas. Turbo and Ion pumps take care of the effluent. A bakeout is done at temperatures of >100º C. Other devices that are baked out are the Tevatron Lambertsons and Seperators.

Barn :

A unit for measuring cross sections. 1 barn = 1024 square centimeters. The units appropriate in high energy physics are usually the millibarn (10-3 barn), the microbarn (10-6), or the nanobarn (10-9 barn).

Baryon :

A collective term for all strongly interacting particles with masses greater than or equal to the mass of the proton. Examples are the proton, neutron, and hyperons.

Basic control :

The ability to change the digital status of a device by interrupting on a parameter page. This function is supported by the database. See basic status.

Basic status :

Digital status of a device as displayed on a parameter page. There are three characters displayed in a standard format (...). The first indicates ON/OFF status; the second indicates the trip/reset status; and the third indicates if the supply is in local or if the breaker has tripped. If all of the digital status for a device is good, three green dots will be present. Some devices have a fourth bit of +/- to show polarity.

Batch :

Group of 83 bunches of beam which are the result of one Booster acceleration cycle. The Main Ring and the Tevatron can contain up to twelve of them.

Batch :

A unit of beam corresponding to the output of one Booster cycle. Up to 12 batches of beam can be injected into Main Ring each cycle.

Baud :

A unit of signalling speed; defined as the number of code elements (i.e. bits) per second.

Bayonet :

A low heat conduction, longitudinally extended connector for cryogenic piping. see Transfer Line.

BCS Theory :

This is the successful theory of superconductivity developed in the 1950's and eventually resulting in the Nobel prize for the authors, J. Bardeen, L.N. Cooper, and J.R. Schrieffer, Phys. Rev. 108, 1175 (1957). This is the classic exposition of the BCS theory.

Beacon :

Message on Linac serial data link flashed by a secondary microprocessor when the link repeater upstream of it fails.

Beam :

A slender unidirectional stream of particles or radiation.

Beam-Beam Tune Shift :

When pbars pass through a proton bunch electromagnetic interactions from the proton bunch affect the pbars as if the proton bunch were higher order corrector that includes both horizontal and vertical quadrupole components. To the protons the pbar bunch like wise appears as a similar higher order corrector. The cumulative affect of these pbar-proton bunch high order correction effects is a shift in the tunes. Thus the term beam-beam tune shift.

Beam Cooling :

The process by which a particle beam's phase space volume is reduced, while conserving Liouville's theorem (there are empty spaces between particles). Beam cooling is manifest by a reduction in the transverse beam size (betatron cooling) or by a smaller momentum spread (momentum cooling). Beam cooling is primarily used these days to accumulate beams of antiprotons for p-p colliding beams physics. There exists two ways of cooling a hadron beam: Stochastic (employed at Fermilab and CERN), and Electron (first demonstrated at Novosibirsk).

Beam Damper :

A device for applying a force on the circulating beam in an accelerator to reduce either the excursions from the equilibrium orbit (betatron oscillations) or from equilibrium phase (synchrotron oscillations)

Beam Dump :

A massive object used to absorb an unwanted beam and dissipate the resulting heat. Dumps for high intensity beams are usually composed of large water cooled metal blocks. They must be shielded from the surrounding environment due to the extreme radioactivity induced by the absorbed beam.

Beam Half Width :

( ah, av ) The direct measure of the beam size usually in mm. Given by

                                              "######### 
                                              &e  b  P 
                                        a  =  & v  v  o 
                                         v    &######### 
                                              !   p P 

For 8 GeV line po = p. 3

Beam Inhibit Light Link Module :

Linac Module through which the H- and I- secondary microprocessors can pull the beam inhibit line.

Beam Intensity :

The average number of particles in a beam passing a given point during a certain time interval, given, for example, as the number of protons per pulse or protons per second.

Beam Line :

Beam line is a collective term referring to all the devices used to control, monitor, and produce a beam having particular characteristics. The common elements of a beam line are magnets, intensity monitors, beam position monitors, and collimators.

Beam Loading :

Phenomenon whereby beam being accelerated by an RF cavity changes the gradient and phase of the RF in the cavity.

Beam Loss :

Loss of protons from the beam chamber.

Beam Roll :

A periodic change in horizontal and/or vertical positions during spill. This doesn't include changes caused by humans.

Beam Sample Pulse (BSP) :

Obsolete. A pulse originated in a module of the MAC-A PDC crate which sent a signal around the ring by way of CC42 cards. It was a two-way communication, with each CC42 card echoing back a response to the BSP controller in the PDC crate. The pulse was used in generating the Main Ring sample time, as well as taking voltage-to-ground snapshots if a ramp current fault occured.

Beam Stacking :

A form of multi-turn injection in which a single turn is injected and then moved by acceleration or deceleration to make room for additional turns. This process, also called momentum space stacking, often appears in storage ring applications.

Beam Stop :

Linac primary critical device in the 750 keV line that blocks the beam path to prohibit beam in Linac. Controlled by CARESS and the pulse shifter.

Beam Stop :

A thick metal shield that moves into the beam line in order to prevent beam from entering a specific area. Beam stops are generally critical devices such as the beam stop in the 750-KeV line and the 200 MeV line beam stop.

Beam Switch :

Toggle switch that will inhibit beam to a particular area of the accelerator on HEP pulses according to the logic in the Beam Switch Sum Box. Eight modules of these switches are found in the MCR.

Beam sync clock :

The clocks MRBS and TVBS, for which the basic frequency is directly related to the revolution frequency of the beam. They are derived from their respective LLRF systems. They operate at frequencies of about 7.5 MHz and produce a clock "tick" every 7 bunches. Beam sync clocks are used for all critical timing of beam transfers between accelerators.

Beam Toroid :

A device used for measuring beam intensities by measuring the magnetic field fluctuations produced by the passing beam. The magnetic field fluctuations produce a current in a coil which is wound around a closed circular ring (torus) through which the beam passes.

Beam Turns :

The width of the beam pulse going to Booster divided by the revolution period of the Booster at injection.

Beam Valve :

A pneumatically operated gate valve that closes across the beam pipe to physically isolate one section of beam line from another. Beam valves are commonly used to isolate vacuum allowing the beamline in one sector or house to be brought up to atmosphere for maintenance while keeping adjacent sections under vacuum. In the event of a vacuum burst beam valves are closed automatically to isolate sectors in order to localize the vacuum problem.

Beamline (transport line) :

A series of magnets and vacuum pipe which carry the proton beam from one portion of the accelerator to another.

Beamline microcomputer :

An NTF computer that monitors beamline devices, dose rates, and communicates with the NTF medical microcomputer as well as the local Linac secondary.

Belly Pan :

A design feature of the Linac tanks that allows leaks in the tank welds to be put under vacuum.

Benelex :

A substance similar to G-10 used to hold NTF neutron collimators in position.

Berm :

Earth shielding over the top of a radiation enclosure.

Berm :

Mound of earth found directly above an accelerator enclosure used to absorb excess radiation.

Berm :

A mound of earth over an accelerator or beam line designed to provide shielding against possible ionizing radiation.

Beta function :

A measure of beam width. The beta function details how the beam changes around the accelerator. There are separate Beta functions for the x and y planes. The square root of bx is proportional to the beam's x-axis extent in phase space.

Beta Matching :

Matching of the beam size to the b of the receiving beam pipe.

Beta (b) Particle :

An electron or positron emitted from a radioactive source.

Betatron oscillations :

Stable oscillations about the equilibrium orbit in the horizontal and vertical planes; these oscillations were the first studied in betatron oscillators, hence the name.

Betatron Oscillation :

Betatron oscillation, so named because it was first discussed for betatron accelerators, is the transverse oscillation of particles in a circular accelerator about the equilibrium orbit. The restoring force for the oscillation is provided by focusing components in the magnetic field which act to bend a particle which is off the equilibrium orbit back toward it. In synchrotron accelerators of modern (strong focusing) design there are several cycles of betatron oscillation per revolution of beam particles.

Bias Pulser :

A Linac module that drives the grid of the 7651 tube in the Buncher RF system.

Bias Supply :

Programmable power supply used to power the ferrite tuners of RF cavities in the Booster and Main Ring.

Bimodal Ramp :

The Main Ring magnets are pulsed to create two flattops to allow extraction at two different energies.

Bipolar Supply :

A power supply that has an operating voltage range of positive to minus. A unipolar supply has an operating range from zero to some positive value.

Bit :

This stands for Binary digIT. It may have a value of zero or one and is the smallest unit of measure. See byte and word.

Bleeder resistors :

In the Linac application, the resistors between the High-Voltage Dome and ground that bleed down the charge on the Dome when the power supply is turned off. 4250 MW.

Blind Scaler :

A scaler made without a display for computer readout only.

BLM :

A device used to measure beam loss from the accelerator. The detectors are sealed ionization chambers. BLM stands for Beam Loss Monitor.

Block Transfer (BTR) :

An option for data transfer in the CAMAC links. Although data is transmitted serially, it arrives at the MAC or front-end in a continuous stream rather than in discrete units. The BTR link is on a separate cable from the CAMAC serial link. It is able to transfer information at a 10 Mbit/sec rate in blocks 196 Kbytes in length.

Blow up :

A relatively sudden and usually catastrophic increase in beam size generally caused by some magnetic field error driving the beam to resonance.

Blowing Up Emittances :

To try to keep down beam-beam tune shifts the emittances of the proton bunches are increased. This is known as "blowing up the emittances". Emittances will also blow up unintentionally when the machine is tuned wrong.

Boiling Point :

Any point on a vapor pressure curve. see NBP.

Booster

The rapid cycling proton synchrotron at Fermilab which receives 200 MeV protons from the Linac, accelerates them to 8 GeV, and injects them into the Main Ring for further acceleration.

Booster Clock :

Obsolete. The booster clock was a continuous pulse train of 1 microsecond pulses that was synchronized to the power line. A signal marking a specific time like T1, T4 T8, was indicated by a missing pulse or gap in this continuous pulse train. These times initiated actions which carried the booster through its cycle. It was the primary time standard for all accelerator systems.

Booster Pulse :

That portion of the beam in the Main Ring resulting from the injection of one booster load, viz., about 1/13 of the Main Ring azimuth.

Booster Serial Link :

This is the CAMAC link to which all Booster CAMAC crates are connected and through which control cards communicate with the Booster Serial (DEC BS) front-end.

Boot :

Restarting a computer by means of loading a fresh copy of the managing program(s). In practice a short program is loaded into memory by hand or with special hardware which then reads in more sophisticated (and longer) programs from mass storage to actually reload the system. The system may be thought of as loading itself by its bootstraps. A reboot is an abbreviation for "remote boot". The PDP-11 and MAC-16 have bootstrap loaders which are permanently stored in read only memory (ROM) while the VAX's store their loaders on a floppy disk.

Boson :

An integral spin particle to which Bose-Einstien statistics apply. Such particles do not follow the Pauli exclusion principle. Photons, pions, alpha particles, and nuclei of even mass numbers are examples of bosons.

Bouncer circuit :

Haefely-designed system used to boost Dome voltage to compensate for charge leaving the Dome during the beam pulse. Not installed at FNAL.

BPM :

A diagnostic device used to measure beam positions. BPM stands for Beam Position Monitor.

Breakover :

When a Main Ring or Tevatron power supply SCR shorts and conducts continuously (i.e., while in bypass, etc.).

Bremsstrahlung :

X-ray radiation caused by deflection of high- energy electrons by atomic nuclei.

Bremsstrahlung Radiation :

Electromagnetic radiation, usually in the X-ray region of the spectrum produced by electrons in a collision with the nucleus of an atom. Bremsstrahlung is German for breaking. Bremsstrahlung radiation is produced in regions of high electric potential such as areas surrounding electrostatic septa and RF cavities.

BSP link :

Obsolete. In a hardware context the link was the physical cable between and including the Main Ring CC42 repeaters. In a software context it was the electrical path which carried the beam sample pulse around the ring. See Beam Sample Pulse.

BSS :

Business Services Section

Bubble Chamber :

An instrument for rendering visible the tracks of ionizing particles. Essentially it is a vessel filled with a superheated transparent liquid, commonly hydrogen or deuterium. The passage of an ionizing particle through this liquid is marked by the appearance of a series of bubbles along the particle trajectory. If the liquid is subjected to a magnetic field, as is usually the case, the charged particle trajectories will be curved, the curvature providing information about the particles' charge and momentum. One or more photographs of the tracks are taken with each accelerator cycle for subsequent study. There were two bubble chambers at FERMILAB, both in the Neutrino Area. A 30-inch chamber with a conventional magnet was located in the N3 hadron beam, and a 15-foot chamber with a superconducting magnet was situated at the intersection of the N5 hadron and No neutrino beams. Both of these chambers are no longer used. The 15 ft chamber was discontinued as recently as 1988.

Bucker :

An air core quadrupole magnet used in the Tevatron to eliminate 4-400 Hz structure in the extracted spill.

Bucket :

Stable phase space area where beam may be captured and accelerated.

Bucket (R.F.) :

A bucket is the stable region in longitudinal phase space. The bucket width gives the maximum phase error or timing error at the R.F. cavity which a particle may have and still complete the whole acceleration cycle. The bucket height is the corresponding limit on momentum error.

Bulk Tuner :

A long copper bar, D-shaped in cross section, that runs the length of a Linac RF cavity and roughly determines the correct cavity volume.

Bump :

A localized orbit displacement created by vertical or horizontal correction element dipoles used to steer beam through available aperture or around obstacles.

Bunch :

A group of particles captured in a phase space bucket.

Bunch Rotation :

Prior to extraction from the Main Ring at 120 GeV, the proton bunches destined to be used for p- production are rotated in momentum phase space by 90R so that a large momentum spread and smaller time spread (a given bunch is narrower in time) comes about. The antiprotons produced retain this structure. Upon injection into the Debuncher, the bunches are rotated 90R thereby reducing the momentum spread and broadening the time structure. This permits the Dp/p of the p-'s injected into the Accumulator to be greatly reduced, permitting smaller magnet apertures and more effective stochastic cooling.

Bunch Satellites :

When a bunch is coalesced it is more than likely that the bunch is not ideally coalesced. There are often secondary bunches in buckets to either side of the coalesced bunch. These are known as satellites and are undesireable.

Bus :

An electrical configuration for transmitting signals within a computer system. Outside of a controls context, the term is also used to denote any carrier of electrical power, such as for the Main Ring or Tevatron magnet currents.

Bus :

A rigid electrical conductor generally for carrying high currents and for power distribution to several devices.

Bypass :

A condition which results in the Main Ring and/or Tevatron power supplies being on but are not producing current. In this condition the three rectifying SCR's are disabled and the bypass SCR's are enabled. In the turning on process both the Main Ring and Tevatron are brought up in bypass before engaging the magnet ramps.

Byte :

A byte consists of 8 bits. It may have a signed value of -128 to + 127.

-C-

C-SEAL :

A metal vacuum seal, usually coated with lead or indium, with a c-shaped cross-section. It is used in high radiation environments where O-ring seals would deteriorate.

Cache :

A small, high speed memory which "borrows" information which has been recently used from the main memory in anticipation that the information is the next to be used. For example, an algorithm on the console computer determines which 50 applications programs have been used most. They are the ones privileged to exist on disk DL1 for easy access. A program not cached has to be loaded from the VAX.

Calorimeter :

A device used to determine particle energies by measuring the ionization of a particle shower in a heavy metal, usually iron and lead.

Calorimeter (Special Usage) :

A calorimeter is a device used to measure a particle's energy. A typical calorimeter is made of a series of scintillators sandwiched between pieces of iron. The incoming particle interacts in the iron creating a hadron shower; the shower is picked up by scintillators, and the particle's energy is measured by the amount of light collected from the scintillators.

CAMAC :

Computer Automated Monitor And Control. There is an internationally accepted set of standards for electronic instrumentation which specifies mechanical, electrical, and functional characteristics of the instrument modules. CAMAC hardware is commercially available. Individual modules (cards) fit into a standard 25 slot receptacle (CAMAC crate) which provides common power, control, and data lines. Booster, Main Ring, Tevatron, Switchyard, Debuncher/Accumulator, RF and Console systems utilize the true standard CAMAC hardware.

CAMAC crate :

A commercially available 25-slot crate used to house CAMAC cards and to interface to the accelerator computer system. The crate has a back plane with connections to all cards in the crate. It has +/- 6 volt and +/- 24 volt DC crate voltages for use by the cards. At Fermilab the last four slots are used by the crate controller. All cards are electrically connected to the crate controller by two sets of busses: each card has its own address line, but they all share the same 24 parallel data lines. Also see Crate.

CAMAC Module :

A "control" card plugged into a CAMAC system for a specific input or output function.

Canned Magnet :

Magnets which are completed encased in their own vacuum jackets.

Capacitor Bank :

A group of capacitors located in the "capacitor tree" outside the Master Substation. These capacitors were used to store energy allowing the Main Ring magnets to ramp at 500 GeV without causing a brown out on the local power grid. Since the Main Ring now only ramps to 150 Gev during collider operation the capacitor tree is no longer used and has been converted into a High Rise apartment complex for migratory birds.

Capacitor Tree :

See Capacitor Bank.

Capture :

The process of putting the beam into RF buckets.

Carbon Resistor Thermometer :

A carbon resistor whose temperature sensitivity provides good temperature resolution, especially below <= 10ºK.

Card :

Modular piece of electronics housed in a crate. Cards are typically used to interface a hardware device with a computer system.

Card (Printed Circuits) :

An insulating substrate to which an electronic circuit is bonded and discrete components are attached. Often used as a synonym for a CAMAC module.

CARESS :

Acronym for Central Accelerator Radiation and Electrical Safety System. Hardware dedicated to monitoring and controlling the accelerator safety systems and critical devices. Independent of any other control system. Located in and below the MCR.

Caution :

This is a software term used to warn console users that they are about to change the analog value or digital state of a device. It is generally used in the interrupt sequence during the control of any device which can cause beam loss, machine downtime, or an unsafe condition.

Cavity (R.F.) :

An RF cavity is a volume enclosed by an electronically conducting surface so that it resonates at some radio frequency. The usual application of the term at Fermilab is to the accelerating cavities in the Booster and Main Ring which resonates at a frequency corresponding to the circulation frequency of the beam and thereby apply a synchronized accelerating voltage.

Cavity Short :

A grounded metal rod that goes in and out of the body of an RF cavity. When a station is off it is still a resonant cavity and can remove energy from the beam. By grounding the cavity it is kept from resonating.

CBA :

Colliding Beams Adrastus. Dave Herrup of the MAD group is responsible for this term. It is the name of a colliding beams tune & chromaticity feedback control system that Dave is involved in.

CC27 Card :

Obsolete. Was the Main Ring abort module. It accepted up to 8 inputs; if any of these sensed an abort condition the abort loop was broken and the abort kickers were fired.

CC48 Card :

Obsolete. Monitored crate voltages and temperatures in the utility crate. It can also acted as an F-slot controller, a secondary crate controller which talked to modules for beam loss monitors, a Johnson controller, and a vacuum ion pump readback.

CC130 Card :

Obsolete. MADC controller for the Main Ring. It was capable of storing a limited amount of data from the MADC and transmitting it back to MAC-A and eventually to MR DEC.

CCI CONSOLE :

Obsolete. A computer console that was manufactured by Computer Communications, Inc. consisting of a color TV display, keyboard, and supporting hardware. CCI Consoles were used at Fermilab in the Main Control Room and the switchyard experimental area control centers for monitoring and control of various accelerator and beam line parameters. CCI consoles in the Main Control Room interacted with devices they controlled through the Xerox 530 and MAC-16 computers, which are also ancient history. In the experimental areas, this linkage was usually through a PDP-11 and MAC-16 computer system.

CD :

Computing Division

CDF :

Collider Detector Facility. A huge colliding beam detector located at B0 experimental facility.

CEA Quads :

Six large aperture quadrupole magnets in the N1 line used for focusing the muon beam. These quads were originally used at the Cambridge Electron Accelerator (CEA).

Cell :

A unit of the Main Ring and Tevatron lattices. A cell runs from one F-quad to the next F-quad.

Centroid :

Technically, the center of mass. Used here to describe the center of a beam profile.

Cerenkov Counter :

A detector for charged particles which consists essentially of a transparent medium such as a gas which emits Cerenkov radiation when a charged particle passes through at a velocity greater than the velocity of light in the medium. The mass of a particle in a beam of known momentum can be determined with such a counter by measuring the characteristic angle at which the Cerenkov radiation is emitted.

Cerenkov Radiation :

Light emitted when a charged particle traverses a medium with a velocity greater than the velocity of light in the medium. The Cerenkov light is emitted in a cone centered on the particle trajectory. The opening angle of this cone depends on the velocity of the particle and on the velocity of light in the medium. The phenomenon involved is that of an electromagnetic shock wave and is the optical analogue of sonic boom. Cerenkov radiation provides an important tool for particle detection. 1

Cesium Boiler :

Electrically-heated crucible in the Pre-Acc dome used to vaporize Cesium used to coat the source cathode.

CH :

DOE Field Office, Chicago

Chamber :

A working volume, not necessarily cryogenic. Ex. Bubble Chamber, EMI Chamber.

Channel 13 :

This is a lab-wide closed circuit TV channel used for displaying accelerator data. The data displayed may consist of machine intensities, experimental area intensity requests, measured experimental area intensities, Main Ring and Tevatron ramp waveforms. For colliding beams the batch intensities, store number, Pbar stacking rate, stack size, etc. are displayed.

Charm :

A physical property (quantum number, degree of freedom) carried by a fourth quark. In the original quark model, three quarks ("up", "down" , "strange") are variously combined to produce the known hadrons. The addition of a fourth quark, the "charmed" quark, gives rise to several new hadron states called charmed particles. Proposed to account for an apparent lack of symmetry in the behavior of hadrons relative to that of leptons, to explain why certain reactions of elementary particles do not occur, and to account for the longevity of the Q1 and Q2 particles. 1,5

CHL :

The refrigeration plant which supplies liquid helium and liquid nitrogen to the Tevatron and Switchyard. CHL stands for Central Helium Liquefier.

Chop Time Selector :

Module in the preacc control room that selects times generated by predets and sends them on to the 750 keV choppers.

Chopper :

Electrostatic device that selectively deflects a portion of the beam pulse to control intensity in the linac or beam turns in booster. Two are found in the 750 keV lines, and one in the 200 MeV area.

Chopper :

A fast electrostatic beam deflector used to select a particular part of the beam during the time that beam is available. The 200 MeV Chopper is a fast electrostatic kicker at the end of Linac that deflects beam to either of two sides of a magnetic septum. One side of the septum bends the beam into the Booster for acceleration while the other side (straight ahead) sends the beam to a dump. Normally most of the beam goes to the dump and only a small amount is "chopped" out for the booster. There is one "chop" for every booster pulse or booster batch.

Chromatic aberration :

Beam spreading out due to different momentum particles being bent by the quadrupole fields at different angles.

Chromaticity :

The ratio of tune spread to momentum spread of the beam.

               Dnx = Cx(Dp/p)

where n is the tune, Cx is the horizontal chromaticity, and p is the momentum. Chromaticity affects the focussing and bending properties of magnets by making them sensitive to particle momentum. This results in focusing and bending dispersion of the beam in a manner analogous to an optical system.

Chute :

Passageway leading from the 200 MeV area to the booster radiation enclosure. The 200 MeV transport line to the booster travels through this.

CLIB :

Acronym for Console object LIBrary. It is a collection of commonly used or convenient routines kept on the Development VAX which can be called upon by applications programmers.

Clock :

A series of digital pulses generated at regular intervals used to mark time. Clocks at Fermilab generally operate at either 15 Hz or in the MHz range, and can be encoded with timing information to be sent around the accelerator.

Clock, (Tevatron) :

Also known as TCLK. Although the name implies it is only used for the Tevatron, it is essentially the master clock for the accelerator. It operates at a 10 MHz rate and is able to transmit encoded events at about a 1 MHz rate. There are 256 possible events (displayed in 2-digit hexadecimal numbers) which the clock can send out.

Clock, (Beam Sync.) :

See Beam sync. clock.

Clock, (Main Ring) :

Most Main Ring events are controlled from TCLK. There is a 1 MHz phase reversal clock dedicated to Main Ring which translates TCLK events into phase reversal events for use by MAC-A, DEC B, and DEC C.

Clock decoder :

Any card, such as a 177 or 279, which recognizes a clock event and acts on it. Most of the decoder modules in the accelerator are based on a custom made Fermilab chip built specifically for decoding TCLK. The 177 modules decode TCLK only; the 279 modules can decode MRBS and TVBS as well.

Clock encoder :

A card, such as a 175 module, which stamps a bit pattern (clock event) onto a clock signal for recognition by a device.

Clock event :

A bit pattern superimposed on the clock frequency at a certain time in the accelerator cycle which is broadcast through the accelerator for decoding and action by a set of devices. Since they are eight bits long there can be a total of 256 unique events.

Clock Generator :

Modules in the preacc control room (one for H- , one for I-) that take the 1 MHz clock and convert it to light pulses to send to the domes via fiber optic cables.

Clock Module :

Module in the preacc control room that converts all the phase reversals on the booster clock to 1-gaps, as well as providing backup 15 Hz and 1MHz clocks for the linac in case the booster clock fails.

Clockodile :

A console applications program which monitors the clock events actually being sent out on the link. It currently resides on D33.

Closed orbit :

The ideal orbit of particles in the accelerator. Betatron oscillations are superimposed on this orbit.

CNSCOM :

CoNSole COMmon. An area in console memory via which information flows between APM, PLD, DPM, and the applications programs (See APM, PLD, and DPM.)

Coalescing :

Coalescing is the production of one high intensity bunch from several lower intensity bunches. This is done by turning on several coalescing RF cavities at F0 that run at 2.5 MHz and 5.0 MHz which are lower than the 53 MHz of the Main Ring RF. The superposition of these two frequencies produces an RF wave that is linear through the region of the bunches to be coalesced. The bunches are pushed into the central bucket and then injected into the Tevatron. During a pbar shot, this can be seen on TV channel MS 30.

Coasting Beam Safety System :

Part of the radiation safety system that protects personnel from circulating beam in Main Ring, Tevatron, and the Accelerator/Debuncher. This system controls beam valves that are inserted into the beam tube to dissipate circulating beam when an unsafe situation is detected.

Coasting Beam Valve :

Special beam line valves that close in order to stop circulating beam in the Main Ring, Tevatron, and Accumulator/Debuncher. These devices are part of the Coasting Beam Radiation Safety Systems.

Cockcroft-Walton Accelerator :

A high-voltage DC accelerator, especially for the acceleration of protons. The DC voltage is produced from a circuit of rectifiers and capacitors to which a low AC voltage is applied. The PreAcc accelerator at Fermilab is a Cockcroft-Walton design.

Cockcroft-Walton Accelerator :

Often referred to as Pre-acc at Fermilab. It is a large electrostatic accelerator which provides the first accelerating step to the protons from the ion source. The Pre-acc increases the energy of the protons to 750 KeV and injects them into the Linac. The apparatus is based on a development of the Greinacher voltage doubling circuit, a constant potential circuit in which capacitors in series are charged in alternate half-cycles.

Cogging :

The process of spacing bunches of protons or antiprotons in the Main Ring or Tevatron so that they will collide at the proper points in the ring. It is used only in colliding beams mode.

Coincidence :

(1) A coincidence or logic unit generates an exactly timed output signal whenever the time overlap of input signals satisfies a preselected coincidence requirement. (2) Occurring or existing at the same time.

Cold Box :

Usually low pressure vessel providing vacuum insulation for cryogenic heat exchangers. Often, loosely, synonymous with refrigerator box.

Cold Cathode Gauge :

An ionization vacuum gauge with no hot filament which uses electrons spiralling in a magnetic field to ionize any gas present. The ions produced are drawn to electrostatic plates. The current produced in this way is interpreted as a pressure. This type of gauge operates down to about 1 E-5 torr.

Cold Valve :

A valve with I zero heat leak. Usually pneumatically activated by a noncondensable gas through long connecting tubes.

Collider Detector at Fermilab (CDF) :

The apparatus used for experiments designed to measure the results of colliding beams of protons and antiprotons. CDF experiments study the highest energy collisions ever produced in a laboratory. This allows physicists to probe much deeper into the structure of matter than heretofore possible.

Colliding Beams :

Oppositely directed particle beams brought together at small or zero angle to produce high energy reactions. Because even the most intense beams are dilute compared to ordinary solid matter used as targets, the beams must be recirculated many times through the interaction point to obtain a useful number of interactions. The apparatus for recirculating beams for long periods of time are called storage rings. The motivation for this arrangement is to make available the entire kinetic energy of the beams in the center of mass of the interacting particles. At Fermilab the two counter circulating beams used are protons and antiprotons. The reason that antiprotons are used is that they only differ in charge from a proton but have the same mass. They can be injected into the same accelerator with the same bend field in the opposite direction and circulate along the same orbit. A proton on proton collider, such as the SSC, requires two separate beamlines to circulate protons in opposite directions.

Collimator :

A collimator is generally a large block of steel or iron, sometimes having an adjustable aperture, that enables one to choose the beam cross section or angular divergence. It is also used to absorb the beam halo and if closed further it can be used to control the intensity.

Collimator :

A movable, solid block of material which can be used to limit beam size or to stop it altogether. They are sometimes used as safety system critical devices.

Collision :

A close approach of two or more particles, photons, atoms or nuclei during which quantities such as energy, momentum, and charge may be exchanged.

COM :

COMputable. A process scheduling state on the VAX meaning that a given process is ready to use the cpu.

Common request list :

When an applications program displays data from accelerator devices it has to generate a list of what information is wanted. This list is assembled on the console computer and consists of DI/PI [device index/property index] pairs. The list is put together in the console computer by the console DPM task from information in the database. It is then organized and sent to the front end for further processing before requests for data are made to devices in the field.

Compiler :

A program which converts programs from problem oriented language (Fortran, BASIC, COBOL, etc.) into machine language.

Compressor Building :

A building located at each zero location of the Main Ring that contains several Mycom Helium compressors. The compressors draw low pressure Helium from the suction header in the Main Ring tunnel and send high pressure Helium along the discharge line atop the Main Ring berm to each of the satellite refrigerator buildings.

Computer Room :

This room is located in the Cross Gallery across the hall from the Main Control Room (South). It houses many of the computers for the Accelerator Division. Included are the Operational and Development VAXs, Console computers, the front end computers, and the associated peripheral equipment.

Computing Counter :

A device that measures pulse frequencies with great accuracy. Used for the display of the linac master oscillator frequency.

Condenser :

An extended surface heat exchanger for the purpose of extracting the heat of vaporization of fluid.

Conditioning :

Vacuum term. The process of running voltage in a septa or separator at a high level over a period of time to clean up the vacuum. After a high voltage beamline device such as a Septa or Separator is baked out it is then run at a high voltage to burn off any oils, dust, or sharp edges that the bakeout didn't get. The voltage is turned on at a low level and slowly raised over time to avoid sparking in the device which can spoil vacuum. By burning off these things the ability of the device to pump down to operating vacuum is greatly improved.

Conduction, Thermal :

Solid heat flow. Similar to electrical conduction.

Convection, Natural :

A transfer of heat by a stream driven by density differences that result from distinct heating and cooling regions.

Convection, Forced :

A transfer of heat by a stream driven by external means between a region and itself, or between regions, of different temperature.

Console :

A standard set of screens and other devices from which an operator or systems specialist controls and monitors devices in the accelerator complex. Each console includes a color TV monitor, a color Lexidata screen, a 613 storage scope, a touch panel and an alarm screen. Each console station is supported by a PDP-11 computer. There are currently 7 consoles in the MCR, and numerous others at locations such as AP-10, Booster West Gallery, CHL, and CDF.

Console crate :

A CAMAC crate which acts as the interface between the console PDP-11/34 processor and the console hardware. It holds the video generator modules (CC130's), the Lexidata interface (134), the 613 interface, and the TSCC crate controller cards which accept serial data coming from the TSCC link driver in the computer room.

Console Disk :

There are two RL02 disks for each console. The top, or "0" disk, contains the operating system and other management programs which are a permanent part of the console. The bottom, or "1" disk, holds the applications programs which usually claim only a temporary residence on the console.

Console hardware :

See Console.

Console Users Guide :

This is an Accelerator Division publication, Software Documentation Memo No. 62.3, which describes the ACNET consoles and contains useful information for writing applications programs for the consoles. Also known as the "Green Book".

Controlled access :

Method used to enter an accelerator enclosure when three conditions have not been met: 1) A radiation survey has been performed in the enclosure. 2) The proper power supplies to the devices in the enclosure have been padlocked off. 3) The safety system has been broken requiring a search and secure.

Controls Hardware Release (HDWREL) :

A type of document published by the Accelerator Division Controls group and distributed within the Division (including the Operations group) which details the operation of new control cards and other hardware built by the Controls group.

Controls Software Release (SFTREL) :

A document also published by the Controls Group which includes detailed information on new applications programs and other software paraphernalia.

Controls Software Update (SFTUPD) :

New versions of Software Releases which update information on applications programs, etc. This type of document is currently being phased out in favor of multiple versions (xx.1, xx.2, etc.) of the Software Release.

Converter :

A thin piece of material used to generate electron- positron pairs from incident photons via the process of pair production.

Cooper Luminosity :

A measure of integrated luminosity when CDF is up and data collecting. Accelerator division integrated luminosity continues to integrate when beam is in the machine even though CDF is down. Cooper luminosity is named after John Cooper of CDF who suggested the measure.

Core :

The most dense region of the p- beam in the Accumulator. Thee beam cooling systems act to 'push' the p-'s into the core and keep them there. The design parameters include:

               intensity          5x1011
               Dp/p 0.05% (H4 MeV)
               emittance          2p mm-mrad (both planes)
               peak density       1x105 eV-1

Core :

The active memory section of a computer system in which stored data may be most readily accessed by the CPU. Generally when program execution is complete, data stored in core is lost.

Corona Rings :

Curved metal surfaces shielding the outside of high-voltage devices to forestall the ionization of air by electric discharges. Used in the HV sources for the preaccelerators. hardware built by th

Correction element :

Additional magnet inserted in an accelerator's lattice to correct for manufacturing defects, variations in power supplies and magnets, obstacles in the beam path, etc.

Coupling :

A generally undesirable situation in which motions in the transverse plane (or transverse-longitudinal) planes are not independent, but are related in some way.

Coupling Capacitor :

A capacitor used to couple AC voltages to parts of an electrical circuit while blocking DC voltages.

CPLD :

Central Program LoaDer. A program on the VAX which loads applications programs onto the console disk. When a program is called by a console computer it works in conjunction with PLD to assure that the console has the newest version of the program.

Cpu :

Central Processing Unit. That part of a computer or microprocessor which performs calculations and makes decisions, as opposed to memory functions, clocks, etc.

CPU (Central Processor Unit) :

The main "thinking" component of a computer system. All arithmetic and logical functions are performed by the CPU of a system. In addition, the CPU is in control of all data acquisition and storage.

Crash Cord :

A yellow and black rope in the Transfer Hall and in some of the experimental target halls. Its purpose is to protect individuals from radiation caused from the beam. If an individual is inside one of these areas and realizes beam is about to be turned on, he pulls the crash cord which immediately turns off the accelerator.

Crate :

A repository for control cards. Each type of crate has a different protocol for accessing and distributing information which must be recognized by the respective front-end. There are CAMAC, NIM, Multibus, Unibus, and several less important types of crates. The cards for each of these crates are not interchangeable.

Crate (CAMAC Crate) :

A standardized receptacle for electronic circuit modules providing a common set of data, control, and power lines.

Crate controller :

The card(s) in a given crate which decodes address information arriving on the link and distributes messages to the appropriate cards in that crate. These cards also arbitrate the data and messages to and from each card in the crate, as they all share the same data lines.

Crate save/restore :

Using the D1 save/restore program to save/restore parameter values of all devices controlled by a particular crate.

Crates and slots page :

An applications program which allows the user to examine the types of microprocessors residing in a given building and its status. There is an individual applications program for each of the serial front-ends (B59, T96, P66, and S54).

Critical Device :

A device that can prevent beam from entering a specific accelerator area. Generally critical devices are designed for fail safe operation. The Radiation Safety System provides permits for critical devices.

Critical Device Failure :

A safety system condition where the Radiation Safety System (RSS) for an area drops before the critical device for that area has been turned off to remove beam from the area. Results in a pulse shifter inhibit and must be reset at the CARESS racks.

Critical Magnetic Field :

This is the maximum magnetic field that a superconductor can tolerate before abruptly returning to the normal resistive state.

Critical Point :

The point on the vapor pressure curve at which the heat of vaporization is zero and the temperature and pressure exhibit a maximum.

Cross Section :

A measure of the probability of the occurrence of a specified interaction between a particular incident particle and a specified target particle or system of particles. Unless otherwise specified, the cross section is given by the reaction rate per target particle for a specified process (e.g. capture), divided by the flux of the incident.

Critical Temperature, Pressure :

The temperature and pressure at the critical point.

Crowbar :

When a device turns itself off, typically due to overcurrent.

Crowbar :

Electronic safety circuits which turn off power when current and/or voltage goes to a dangerous level.

Crowbar Compare Circuit :

Modulator and PA protection circuit that shuts down the RF system if the current from the modulator to the PA anode exceeds certain limits.

Cryogen :

By convention one of the gases condensing below 150ºK.

Cryogen :

A refrigerant to be used in a refrigerator for producing low temperatures. To reach superconducting temperatures, liquid gases such as Nitrogen are used in succession with liquid helium to reach the lowest temperatures. 1

Cryogenic :

A system or equipment that operates at a temperature set by convention at 150ºK.

Cryogenic Valve :

see Extended Stem

Cryogenics :

The production and maintenance of very low temperatures, and the study of phenomena at these temperatures.

Cryogenics :

Cryogenics is the technology of the production and effects of very low temperatures. The adjective "cryogenic" is frequently used when describing liquid hydrogen targets and the phenomena of superconductivity. The niobium-titanium alloy used for superconducting magnets becomes superconducting at a temperature of 11 degrees K.

Cryostat :

A vacuum insulated vessel for cryogenic fluids. see Dewar.

Cryostat :

A vessel for maintaining a constant low temperature.

CTF :

Cancer Therapy Facility. Now called Neutron Treatment Facility (NTF). A small area in the Linac Gallery devoted to cancer treatment using neutrons produced on a beryllium target by 66 MeV protons diverted from between the fifth and sixth tanks of the linac during periods when it is not needed to fill the Booster. The facility consists basically of the neutron beam line, a treatment enclosure with patient positioning apparatus, a few offices, patient preparation rooms, etc.

CUB :

Central Utility Building. This facility provides LCW for accelerator cooling as well as chilled water for air conditioning systems. It is located directly behind the Booster pond.

CUR :

CURrent. A process scheduling state on the VAX indicating that a given process is currently operating.

Cursor :

A visible marker on the screen which indicates where on the screen a user may be interacting with the program.

CURVES MAC :

Obsolete. This was a MAC-16 computer located in the Mac Room (see Mac Room) and used for calculation of the ramps for the Main Ring RF high and low level systems.

CVT :

Stands for Constant Voltage Transformer. It provides proper voltage for Main Ring and Tevatron power supply SCR firing circuits.

Cyber :

These were computers present in the High Rise which were used primarily for analyzing experimental results. Accelerator Division personnel did not normally use the Cybers but could access them through the proper port selector connections at the terminals. There were three Cyber 175's which each had 256k-60 bit words of memory, and one Cyber 875 which had a million 60 bit words of memory. The Cybers shared the workload of experimental analysis with the VAX cluster in the High Rise. The Cybers are no longer with Fermilab. Sometime ago they were obsolete and sold for scrap.

Cycle Period :

The length of time between successive repetitions of a periodic phenomenon. The Fixed Target cycle consists of injecting the beam into the Main Ring, raising the magnetic field and accelerating the beam to 150 Gev, injecting the beam into the Tevatron, raising the Tev magnetic field and accelerating the beam, extracting the beam to Switchyard experimental areas, reducing the magnetic field in the accelerators and preparing for the next injection. The Fixed Target cycle time is about 60 seconds. The Colliding Beams cycle is 120 seconds long. Each of the Colliding Beams preparation steps are in 120 second cycles as well as the ramp up to 900 GeV and the low beta squeeze cycles.

Cyclotron :

A particle accelerator in which the particles move in a constant magnetic field in a spiral orbit, the energy of the particles begin increased by the application of an alternating electric field at constant frequency. Authors side note. In college we actually made one of these in a coffee can being blissfully unaware of the X-ray or Radiation hazard we had created. It was demonstrated for a professor and promptly confiscated to disappear into the low level radiation storage locker never to be seen again.

Cyclotron Magnet, Chicago :

The large magnet from the synchrocyclotron used by Fermi and his colleagues at the University of Chicago now used not as an accelerator, but as a particle-momentum analyzing device (spectrometer) in the N1 muon beam of the Neutrino Area. It is located in the Muon Lab Enclosure. The magnet is so massive that it was moved in several pieces, assembled and the building then built around it.

-D-

D/A :

Digital to Analog converter (hardware) or a setting value for a device (software). The hardware is a unit which accepts a number from the control system (binary encoded) and converts it to a corresponding output voltage. Such a device is the complement of an A/D converter. In many instances the output is used to program the output of a power supply. In such a situation the transfer function of the power supply is assumed to be a constant. A user should be aware of this potential problem. Most D/As in the accelerator control system output voltages in the range of -10 to 10 volts and have a resolution of 12 bits (including the sign bit).

D0 Collision Hall

Collider Detector at D0 interaction region.

D to A Line :

The transport line joining the Debuncher and Accumulator. Extraction/injection is realized by means of sets of pulsed magnetic septa and kicker magnets all oriented to displace the beam horizontally. The Accumulator injection kicker is unique in that a physical shutter moves into the aperture when the kicker is fired to shield the already circulating stack from the magnetic field if the kicker (only the injected beam is perturbed).

DABBLE :

An interactive program on the Operational VAX which implements changes in the system database.

DAC :

Digital-to-Analog converter. It is an electronic circuit which takes a digital message, usually transmitted on a link, and converts it to an analog voltage for use by a device. This usually means that the circuit has many input lines (generally 8, 12, or 14) corresponding to the number of bits in the digital word and a single output line whose voltage represents the sign and magnitude of the digital word.

Damper :

Device used to damp out coherent transverse beam oscillations.

Dark Current :

Current that flows from a photomultiplier tube in the absence of light. The main sources of dark current are ohmic leakage due to imperfect insulation and thermionic emission.

Data Selector :

Part of the monitor/control module for the Haefely power supply which selects either the voltage readback or the command voltage for display on the front of the module.

Database :

A list of properties for each device on the ACNET system, kept on the Operational VAX. These properties include mnemonics, alarm limits, descriptor texts, and scaling information.

Datalogger :

A program residing on the VAX which allows for the automatic and regular acquisition of data from a given set of devices, each with its own frequency. The limit is about 900 devices.

DBM :

This acronym stands for Data Base Manager. This is a process on the VAX which maintains the database. All accesses to the information in the database must be through routines which interface with this database manager.

DBPEEKER :

A program on the operational VAX which allows the user to look at the database of a particular device or set of devices.

Debuncher :

A radio frequency cavity phased so that particles at the leading edge of a bunch of beam particles (higher momentum particles ) are decelerated while the trailing particles are accelerated, thereby reducing the range of momenta in the beam. Such a device may be placed between two stages of acceleration to increase the efficiency of capturing the beam in the second stage as, for example, with the 200 MHz debuncher cavity installed between the Linac and Booster at Fermilab.

Debuncher; Booster :

Something of a misnomer. The debuncher is used to reduce the momentum spread of the Linac beam by decelerating particles with higher than nominal energy and accelerating those with lower energy.

Debuncher ;

The first of the two rings (as seen by the pbars) comprising the Antiproton source. The Debuncher designed to accept a pulse of newly produced antiprotons, bunch rotate and adiabatically debunch the beam, then betatron cool the beam in preparation for injection into the Accumulator. Design parameters include:

               kinetic energy     8.0 GeV
               average radius     80.42 meters
               number of pbar-bunches injected       80
               momentum aperture Dp/p     4%
               btron acceptance   20p mm-mrad
               btron tunes (H & V)        9.75
               periodicity        3
               phase advance/cell 60R

DEC :

Digital Equipment Corporation, manufacturers of the PDP and VAX series computers and perpetrators of the UNIBUS.

DEC-B :

This is a PDP-11/55 computer located in the Mac Room. It is used for Main Ring power supply calculations.

DEC-BS :

This is the Booster Serial front-end, a PDP-11/44, located in the Computer Room. It is used to interface and control devices on the Booster Serial Camac Link.

DEC-C :

This is a PDP-11/55 computer located in the Mac Room. It is used for Main Ring Power Supply ramp control.

DEC-P :

This is the Antiproton front-end, a PDP-11/44, located in the Computer Room. It is used to interface and control devices on the Antiproton Serial Camac Link.

DEC-S :

This is the Switchyard front-end, a PDP-11/44, located in the Computer Room. It is used to interface and control devices on the Switchyard Serial Camac Link. These devices include all Switchyard devices, most 8-Gev devices, and TCLK.

DEC-T :

This is the Tevatron front-end, a PDP-11/44, located in the Computer Room. It is used to interface and control devices on the Tevatron Serial Camac Link.

Decay :

A transformation in which an atom, nucleus, or subatomic particle changes into two or more objects whose total rest energy is less than the rest energy of the original object.

Decay Length :

The average distance a species of a particle at a given energy travels before decaying.

Decay Muon :

A muon produced via pion or kaon decay.

Decay Pipe :

The 400 meter long beam pipe downstream of the Neutrino Area target train. The p and K particles produced at the target decay in flight through the decay pipe into the muons and neutrinos used by the experiments. The length of the decay pipe is determined by the decay half-life of the p and K particles and their velocity.

Deceleration :

The process of decelerating the antiproton stack to a set momentum for the E760 experiment located at AP50 in the Antiproton Source

DECnet :

A system developed by the Digital Equipment Corporation which links the DEC computers together. Just about any DEC computer system (worldwide) may be connected to DECnet so that a communication link may be established between computer systems. Decnet is the largest single computer network in the United States.

Decwriter :

A hardcopy terminal located in the computer room. There are dedicated Decwriters which interface with each of the VAX computers and other Decwriters that can be connected to the PDP-11's.

Defocussing Quadrupole Magnet :

A quadrupole magnet that focuses beam in the vertical plane and defocuses in the horizontal plane.

Density :

The mass per unit volume of anything. (g/cm3)

Detector Building :

The airplane hanger shaped building in the Meson Area providing weather protection, crane coverage, and utility connections for the "upstream" end of the experiments in that area. Beam line monitoring and tuning is also conducted from the operations area on the mezzanine floor of the Detector Building. Also called Meson Hall.

Deuteron :

The nucleus of the deuterium atom (an isotope of the hydrogen) consisting of a proton and a neutron.

Development VAX :

This is a VAX-11/785 used for software development. It is located in the Computer Room.

Device Index (DI) :

This is a number assigned by DBM to all devices entered into the database. This number is then used by software routines to access information about a device from the database.

Dewar :

A vacuum insulated, cryogenic radiation insulated, low conduction heat loss vessel for cryogenic fluids.

Dewar :

A dewar is a vacuum insulated container for keeping material, chiefly liquids, cold or hot. The common thermos bottle is an example of a dewar. In the accelerator business dewars are often used to store large quantities of cryogenic liquids. In Pbar the nitrogen dewars are used to submerge the stochastic cooling electronics in order to reduce the amount of thermally induced electronic noise.

DFG :

Acronym for Dipole Function Generator. It is the card which controls and provides the output waveform for the Tevatron correction dipole regulators. These are also known as 160 modules.

Diffracted Beam :

Particles exhibit wave like characteristics in their passage through matter. In striking a target the incident beam scatters off nucleons. The scattered waves then combine according to the superposition principle and the peak of this scattered wave is called the diffracted beam. Diffraction takes place when the wavelength of the incident beam is short compared to the interaction distance.

Diffusion pump :

After a mechanical (roughing) pump is used to remove about 99.99% of the air in the beam tube, the remaining air can then be removed by a diffusion pump, down to about 1E-5 torr.

Digital Status :

Indicates whether a given device is on or off, and whether or not it has been reset. Usually there are also digital bits which signify interlock status, etc.

Digital Voltmeter (DVM) :

A modern solid state device capable of measuring voltage and displaying the value in digitized form. The term is also used loosely for the digital multimeter which can measure current and resistance as well.

DIO :

Direct Input/Output. It is generally used in the context of processor I/O.

Dipole :

A magnet with two pole faces, used to bend the beam either horizontally or vertically.

Direct Muon :

A muon produced by the direct interaction of a proton with a target rather than produced as a decay product.

DISC Cerenkov Counter :

A DISC (Differential Isochronous Self- Collimating) Cerenkov counter is used to identify particles over a wide range of masses and can also be used to give an independent calibration of the average momentum of a beam line. The DISC Cerenkov counter at Fermilab is located in the M6 beam in the Meson Lab.

Discriminator :

A discriminator is a circuit that accepts signals of various shapes and amplitudes, and for each input signal that is above threshold, it outputs a standardized logic pulse. The outputs are of standard amplitude and duration, completely independent of all characteristics of the input except time of occurrence.

Disk :

A device carrying magnetically encoded information which can be read by a computer system. The information load is usually in the few to hundreds of megabytes range.

Diskette :

Also known as a "floppy disk". A small device which carries magnetically encoded information readable by a computer or microprocessor.

Dispersion :

Quality of a beam transport system at a given point that defines the variation of the transverse position of the beam with variations in beam momentum. Usually expressed in meters.

Dispersion :

Spread in beam positions due to a spread in particle momenta. ( Dx = Dx(z)(Dp/p) --> where Dx is the horizontal dispersion as a function of z, the longitudinal coordinate )

Dispersion (high and zero) :

Dispersion of the momentum variety can be looked at as the size of a beam as a function of the momentum spread. Dipoles can create dispersion or take it away (particles of different momenta will be bent at different angles by a dipole with uniform field), as can quadrupoles. In the case of the Antiproton source, high dispersion regions are good places for beam pickups to sense improper momenta- a good place to install momentum cooling pickups. Low (or zero) dispersion regions are suitable for sensing beam displacements primarily due to btron oscillations- similarly a good region in which to install pickups and kickers for btron cooling systems. As an aside, momentum cooling kicker electrodes are also placed in low dispersion areas, because placing them in high dispersion areas could induce unwanted heating of the beam.

Divergence :

The angle that the trajectory of each particle makes with the beam axis. Accelerator systems always try to reduce beam divergence.

DL0 Disk Drive :

The upper disk drive on a console PDP-11/34. It contains the console operating system management programs and system common block areas.

DL1 disk drive :

The lower disk drive on a console PDP-11/34. It contains images of the most used applications programs on that console.

DOE :

U.S. Department Of Energy

Dogleg :

A two (or more) dipole system which first bends the beam away from a given path and then straightens it so that it parallels the original path.

Dogleg :

A shifting of the beam axis by a pair of dipole magnets, such that the initial and final beam axes are parallel.

Dome (Pre-Accelerator) :

The -750 kilovolt direct current terminal of the Cockcroft Walton preaccelerator containing, among other things, the proton source for the accelerator.

Dosimeter :

An instrument used for measuring or evaluating the absorbed dose of radiation. It may depend on the measurement of ionization for its operation or may simply involve the darkening of a piece of photographic film ("film badge").

Dome :

A large rounded box, maintained at a high potential, that houses the ion source and supporting equipment in the preaccelerator.

DOSYL :

DOcument SYstem Locator. A documentation system residing on the Development VAX which is used to reference Operations Bulletins, Technical Memos, Software Releases, etc. It contains information which can be accessed by keyword, date, author, or subject concerning major documents released by the Accelerator Division or the Publications Office.

Doublet :

A system of two quadrupoles in close proximity, and with opposite polarity, used to simultaneously constrain the beam size in two dimensions at some point downstream.

Doublet (Quadrupole) :

A beam optical system consisting of two quadrupoles of opposite sign which provides net particle focusing in all planes.

Doughnut club :

The group of Physicist, Specialist, and Techs that gathers each morning to read the bulletin board in the west entrance MCR while eating doughnuts and spilling coffee.

Download :

To write an operating program from one machine to another. Often the programs are stored in one machine and written onto the second if problems develop during operation.

Downstream :

A relative term which corresponds to the direction that the protons travel in that portion of the accelerator.

DPM :

Data Pool Manager. A task on the console computer which accesses the database in the VAX in order to organize request lists for setting and reading data.

DRF1,2,3 :

Like the Accumulator, the Debuncher employs 3 unique radiofrequency systems. DRF1 is an h=90 (53 MHz) system used to capture the p- bunches as they are injected, rotate the bunches 90R in phase space to reduce their momentum spread, then to adiabatically debunch the beam. It may not be obvious, but the p-'s coming off of the production target will retain the same RF structure as the incident protons had, hence DRF1 can be flocked to MRRF. There are 2 unique types of cavities comprising DRF1. Cavities 1 and 8 are referred to as adiabatic cavities and are able to operate at a lower voltage than the other 6 cavities in order to adiabatically debunch the beam. Cavities 2-7 are called 'Rotators' and primarily serve the function of capturing and bunch rotating the injected pbars. DRF2 is a barrier bucket system operating at h=4. The Debuncher is physically longer than the Accumulator, by H200 nsec, so a gap is put into the circulating Debuncher beam to make the beam fit into the Accumulator. This also permits time for kicker magnets to reach full field without perturbing the beam. DRF2 creates one bucket (the other 3 are suppressed) which prevents particles from entering, hence a gap in the beam is created. The bucket height of DRF2 is greater than the beam energy spread, so a barrier is created. DRF3 is also a h=4 system and is used only during studies as an aid in exploring the aperture, chromaticities, and other properties where moving the beam around the aperture radially is useful. Varying its frequency permits one to move the beam to the inside or outside of the central orbit.

Drift Chamber :

A series of drift chambers are used to detect particle trajectories. They are similar to multi-wire proportional chambers, except the wire spacing is increased. The correlation between the position of an ionized track produced by a charged particle and the time of appearance of an electric pulse at the wire is used to measure the distance of the trajectory from the wires.

Drift Tube :

In Linac a long copper torus, containing a quadrupole magnet, through which beam passes during acceleration in a linac RF cavity. The beam is shielded from the electric field in the cavity while in the drift tube, and is accelerated by the field while passing between drift tubes.

Drift Tube :

Tube inside a Linac RF cavity in which beam is protected from the sinusoidally varying accelerating field when the field gradient is against the forward momentum direction of the beam. When the beam travels out of the drift tube and into the accelerating gap the beam sees a positive gradient and is accelerated.

Drive Loop :

Termination of the Linac coaxial transmission line leading from the PA to the RF cavity which couples the energy in the transmission line to the magnetic fields in the cavity.

Driver :

The 4616 power amplifier tube (200 kw output) used in linac to drive the 5 MW PA.

Dry engine :

Cryogenic device which cools the helium by allowing it to do work against a piston. It is used to cool the shell side of the heat exchangers. other properties

Dugan :

Pbar term. Unofficially used to describe the rate of stacking pbars. 1 Dugan = 1 mA/Hr. Named in honer of Dr. G.Dugan who used to be head of pbar.

Dumb module :

A relative term designating any card or module which does no on-board data processing or error checking. For dumb modules these functions are usually performed by the front- end.

Dump :

An area of steel and dense concrete into which unwanted beam can be steered so that its energy can be dissipated in a safe and controlled manner. This term also refers to a Tevatron ramp trip during which the stored energy of the ring is dissipated through high power resistors.

Dump resistor :

Resistor which is switched into the Tevatron magnet circuit in order to dissipate the stored energy in the magnets in the event of a ramp trip.

Duoplasmatron :

A type of ion-producing source that develops protons by extracting positive ions from an arc struck in hydrogen gas. The I- source in the PreAcc used to be a duoplasmatron. Both sources are now magnetrons.

Duplex :

Simultaneous two-way independent transmission in both directions. This may also be referred to as full duplex.

Dynamics :

The study of the motion of particles under the influence of forces. Dynamics deals with the causes of motion, as opposed to kinematics which deals with its geometric description.

-E-

E17 Kicker :

The kicker magnet responsible for moving Main Ring beam from the circulating orbit to the extraction orbit for injection into the Tevatron. The misfiring of this magnet can result in severe quenches in E and F sectors.

E-Z Writer :

Applications programs which store commonly used plot information for convenient display on the Lexidata or storage scope. Currently residing on D77, B67, M77, M78, T102, T107, S67, and P77.

EAD :

Experimental Areas Division. The downstream beam area of Switchyard. Switchyard Operations Department and switchyard experiment areas are part of EAD.

Early Bird Report :

At the end of owl shift the Main Control Room crew chief writes a one page summary of the past 24 hrs and the proposed schedule of accelerator operations for the next 24 hrs. This summary is then posted on the bulletin board outside the west MCR entrance with the last 24 hrs of the log book.

East (West) Anode Supply :

The high voltage d.c. power supply for the anodes of the power amplifiers located under the east (west) gallery of the booster.

Echoing :

The returning of information from a computer or some part of the control system to insure that the information was received correctly.

Eddy Current :

Localized current flowing in a conductor in response to a changing magnetic field.

Electron :

A stable, elementary, negatively charged particle. Electrons have the smallest amount of mass of all the subatomic particles. Electrons may be in bound states around nuclei where they determine chemical properties of elements, may radiate through space as electron beams or g-rays or through conductors to form an electrical current. Electrons are spin 1/2 fermions and interact via the electro-magnetic and weak forces.

Electron Shower :

These are usually called electron-photon showers and are made by high energy electrons or photons passing through a medium. A parent electron radiates photons in traversing a medium, and the photons convert to electron-positron pairs, which again radiate. The number of electrons and photons therefore increase exponentially until ionization loss becomes important and no further radiation is possible.

Electron Volt (eV) :

The amount of kinetic energy gained by an electron when it is accelerated through an electric potential difference of 1 volt. It is equivalent to 1.603x10-12 erg. It is a unit of energy or work, not voltage. Particle energies at FERMILAB are typically measured in billions of electron volts (GeV).

Electrostatic Septum :

The septum is the principal component of a beam splitting system. Static electric charges produce a different field on opposite sides of the septum. Segments of beam on opposite sides of the septum will be deflected opposite directions, thus cutting the beam into two parts, or "splitting the beam".

EMC :

Event Message Code. A list of alarms assembled by the appropriate front-end. This list is eventually given to AEOLUS, which organizes the data for display on the alarm screens.

Emergency loop :

System of microswitches which when opened (by pulling on a crash cord on the tunnel wall) will disable the radiation and electrical safety systems for that particular enclosure.

EMI :

The EMI (External Muon Identifier) is a set of muon detectors (proportional wire chambers) attached to the outer shell of the 15-foot bubble chamber. In conjunction with the chamber it aids in the interpretation of neutrino and antineutrino interactions by positively identifying muon tracks in the chamber. Note that the 15-foot bubble chamber is no longer used.

Emittance :

The area in phase space occupied by a particle beam. The units are mm-milliradians for transverse emittance and eV-sec for longitudinal emittance.

Emittance :

( pe ) Defined as the effective area of the beam in phase space and given by ?x' dx where x' is the divergence.

Emittance Probe :

Linac device used to measure the size of the phase space ellipse occupied by the beam, done by measuring the divergence of the beam at a number of points across the beam axis.

Emulsion (Nuclear) :

A photographic substance designed for the detection of ionizing particles. When high speed charged particles traverse the emulsion, they cause ionization tracks which show up when the emulsion is developed. The charge, energy, and momenta of the particles may be deduced from their range in the emulsion, from the grain density of their tracks, and from their curvature in a magnetic field.

Enable :

A request for beam sent to the prom module in the preacc control room. Three types of enables exist: HEP, NTF, and P-bar.

Enclosure :

A portion of the accelerator tunnel.

End pulse :

Pulsing of the QXR magnets at the end of flat top to extract the final fast spill. An attempt is made to extract all the beam remaining in the Tevatron during that pulse.

Energy Doubler/Saver :

The name originally given to the Tevatron. It is an "energy doubler" because it permits acceleration of protons to about 1000 GeV which is twice the energy attainable in the Main Ring. It is an "energy saver" because the superconducting magnets permit the acceleration of beam using less electrical energy than the Main Ring uses to reach the same energy. 1

Enthalpy :

The sum H of the internal energy U and the work energy PV of a fluid at a given temperature and pressure.. H = U + PV. (J/g)

Entropy :

The measure of system disorder. The function of state of a thermodynamic system. (dQ/dmdT) EPA :

Environmental Protection Agency

EPB :

Extracted Proton Beam. This term refers to 5 and 10 foot dipoles and quadrupoles originally designed for use in the Switchyard.

EPO :

Environmental Protection Officer

ERM :

Event Request Modules. These are the CAMAC 175 Modules which encode events onto the Tevatron clock. They are located in the MAC room.

Error Codes :

Messages which appear in red on the TV or Lexidata screens which carry information about the controls system pertinent to the fact that you have no data. These messages can be deciphered from D11 or using the error help facility under the utility window on the consoles.

ES1, ES2 :

Electrostatic Septa 1 and 2 responsible for guiding Tevatron beam to the extraction orbit for delivery to switchyard. ES1 and ES2 are located at D0.

ES&H :

Environment, Safety and Health.

ESEP :

Vertical splitting septa in the proton line. It is called ESEP because it is located in enclosure E in Switchyard.

ESHPAC :

ES&H Policy Advisory Committee

ETHERNET :

The link and communication protocol which is generally used between computer systems. It is a half-duplex link which transmits data serially (both directions) at a 10 Mbyte rate. The primary use in the Accelerator Division is for the link between the Linac front-end (a PDP-11) and the Linac Primary Station (a 68000 microprocessor). This type of link is also used on site for the DECnet link between the AD VAXCluster and the FNAL VAX Cluster.

Ethernet Controller Board :

Board found in the linac primary microcomputer that handles communication with the Ethernet link.

Eurobus Crate :

One of two small crates in the preacc control room containing cards used to interface the local microcomputer to the Haefely power supply controls.

Expansion :

To make the volume in which a given mass, or mass flow, resides suddenly larger as in Joule-Thomson and engine expansion.

Expansion Efficiency :

The ratio of the actual change in enthalpy to the ideal (isentropic) change.

                                                DH Real 
                                        eff. = ########## 
                                                DH Ideal 

Expansion Engine, Turbine :

Devices that are driven by gases, extract work, and lower the temperature of the gas.

Extended Stem :

Modifier for valves with long stems for cryogenic service.

External Interrupt Panel :

This 16 input panel (with on/off switches for each input) is used to interface external interrupt signals, which may be clock events, to the computer processor interface cards. These panels are located behind the PDP-11 Status Display Units and are also behind the Mac computers.

Extraction :

The process of taking the protons out of the accelerator in a controlled fashion once acceleration has been accomplished. Extraction from the Tevatron takes place during the flattop of the ramp.

Extraction :

The controlled removal of beam from one portion of the accelerator in order to send it to the next one.

Extractor :

An electrostatic device used to extract ions from the magnetron ion source in PreeAcc. It consist of a pair of plates mounted beneath the source connected to a pulsed power supply.

-F-

F slots :

A set of five slots in the modified CAMAC crates for Main Ring (Utility Crates) which are denoted by F0, F1, F2, F3, F4. The last four slots may only be addressed by a card residing in the F0 slot. These slots are said to have subaddresses. Only the card in the F0 slot may be addressed by the crate controller. This slot is currently filled by a CC48 card.

F slot controller :

The CC48 card in the F0-slot which controls cards in the succeeding slots (F1-F4) in a modified CAMAC crate. (See above)

Factory (antiproton) :

An installation where Antiprotons are produced and accumulated. Fermilab's Antiproton source, consisting of the Target station, Debuncher and Accumulator rings, and the associated transport lines, is a good example of an Antiproton factory. It is hoped that this factory will eventually produce 5X1011 p-'s every 8 hours. The best so far has been 1.2X1010 per hour.

Fail Safe Mode :

A situation in which the failure of a component results in a safe condition. The critical devices of the safety system are designed to be fail safe, ie. they will not allow the transmission of beam pass the critical device.

Fan-in :

A board or other device which gathers signals from a variety of devices and consolidates them for processing (as with an MADC).

Fan-out :

A board or other device which receives a signal, replicates it, and sends it out to a number of devices.

Fan-in and Fan-out :

A fan-in is a module that performs the function of linearly adding either analog or logic signals. A fan-in is often used to perform high-order majority logic decision. (e.g., any 6 out of 32) by attenuating each input and discriminating on the summed output. (Many inputs, few outputs.) A fan-out is a module used to distribute a fast signal to several 50W loads with no loss in signal amplitude. (Few inputs, many outputs.)

Fast pulse :

See Fast spill

Fast spill :

The resonant extraction of intense pulses of protons using the QXR system. These pulses last only a few milliseconds. This is sometimes referred to as a Fast pulse.

Fast Time Plot :

The standard plot generated on a Lexidata or Storage Scope. The sample rate is usually generated automatically, but the range and length of time are selected by the user.

Fast trip :

Automatic turn off of the Main Ring ramp in the event of a fault.

Fast Trip :

The switching off of a power supply or supplies (e.g. Main Ring or Tevatron power supplies) in response to a signal from an overcurrent, overvoltage, or ground fault detection circuit.

Feed Can :

Device which connects the satellite refrigerators to the magnet strings. At every '1' and '4' building there is a normal feed can, and at every '2' and '3' building there is a power feed can. The power feed cans are the points where the power supply bus enter the cryogenic system.

Feeder :

Underground cable(s) which delivers power from the Master Substation to various accelerator sites.

Feeder :

A 13.8 kV electrical power distribution cable running between the Master Substation and a unit substation near the location at which the power is used.

Fermilab Clock Decoder :

A custom-made integrated circuit which decodes TCLK for internal use on a board.

Fermion :

A generic term for half integral spin particles to which Fermi-Dirac statistics apply (total wave function antisymmetric under identical fermion exchange). The Pauli Exclusion Principle applies for such particles (two fermions cannot simultaneously occupy the same quantum state). Examples are electrons, protons, neutrons, muons and hyperons.

FESS :

Facilities Engineering Services Section

Fiber-optic Link Repeater :

Chassis associated with Linac primary and all Linac secondary microcomputers that maintain continuity of the serial data link and control the microcomputers' interfacing with it.

Fiducials :

In general, reference marks to which particle trajectories are compared; may apply to wire spark chambers, optical spark chambers, bubble chambers, etc. In particular, permanent reference markings in SWIC displays to facilitate the referencing of beam trajectories in beam lines.

Fiducial Volume :

The volume of a detector or spectrometer system within which events are accepted as measurable.

Field Lamp :

Light source between the NTF primary and main collimators designed to duplicate the profile of the neutron beam with any given collimator insert. Used in patient set-up.

FILEMASTER :

This is a user account on the Operational VAX which coordinates the creation, deletion and modification of all filesharing files on the AD OPER VAX. This also keeps track of all files on a master list.

Filesharing :

This refers to a type of file access system established on the OPER VAX. This system allows shared access to files from any connected node. This means that any console, front-end, OPER VAX process, or DEV VAX process may read from or write to a filesharing file.

Film Badge :

A device worn by those who work in radiation areas to record the amount of exposure the individual has received over a one month period.

Filter :

A device to separate particulate matter. In cryogenics includes frozen matter.

Finite State Machine (FSM) :

An applications program currently residing on T13 which controls the refrigerators during automatic quench recovery or automatic cooldown.

FIRUS :

Acronym for FIRe and Utility System. A site-wide alarm system which reports alleged fires, power failures, pump alarms, etc. The FIRUS screen in the MCR is edited to report only those problems relevant to the Accelerator Division.

Fixed target :

Mode of operation during which experiments are carried out on particles produced when the original proton beam strikes a stationary object (target).

Fixed Target :

Any stationary spot to which the beam of protons is directed and with which the beam collides or interacts. This could be a piece of metal, liquid hydrogen (bubble chamber), or some other detector.

Flattop :

(1) The portion of a magnet current excitation cycle in which the current is maintained constant at its maximum value. The maximum magnetic field (corresponding to the maximum particle energy) maintained in the Main Ring during beam extraction, the "top of the ramp". (2) To excite a pulsed magnet with a current waveform containing a significant constant current portion at the highest current.

Flat top :

That portion of the accelerating cycle during which the particle energy is constant and at its maximum value. This applies to both the Main Ring and the Tevatron. This can also refer to the portion of a power supply's output waveform during which its output is constant and at its maximum.

Flow Orifice :

A carefully constructed hole used to measure flow by the small pressure difference across it. Temperature and Pressure dependant.

Fluid :

The gas, liquid, or mixed phase of a cryogen.

Flying Wire :

A single wire that is rapidly passed through the beam. The wire in the beam causes beam loss which can be plotted as downstream BLM vs. wire position. This gives a profile of the beam. Flying wires are passed through the beam horizontally or vertically for horizontal or vertical beam profiles. Flying wires are used in the Main Ring, Tevatron, Booster and Pbar.

FNAL :

Fermi National Accelerator Laboratory

Focal Length :

The distance from the center plane of the lens at which an input beam, parallel to the axis and displaced from the axis, crosses the axis after passing through the lens. The point where the beam crosses the axis is known as the principal point of the lens.

Focussing Quadrupole Magnet :

A quadrupole magnet that focuses beam in the horizontal plane and defocuses beam in the vertical plane.

Foreline :

A vacuum line leading from a vacuum pump to the device or devices to be pumped.

Fortran 77 :

This is the version of Fortran supported by the VAX and PDP compilers.

Forward Power :

The power transmitted from one stage of an RF system to the next, which may not represent the full power of the first stage due to power reflected from the second (reverse power).

Four-Momentum :

The relativistic generalization of momentum which describes the energy and momentum. It is a Lorentz 4-vector whose time like component is the energy and whose space like components are the momentum components. The four-momentum is easily transformed from one coordinate system to another (Lorentz transformation) and its product (Lorentz product) with any other 4-vector is independent of the particular coordinate system used (Lorentz invariance).

FPS-164 :

This is a Floating Point Systems 64-bit processor attached to the ADCALC VAX. This is typically used for accelerator calculations where the increased accuracy and high performance is needed. It is different from a computer as it contains only disks and no other peripheral or I/O equipment, so that it requires the services of the ADCALC VAX to load and execute user programs.

Frequency Control and Phase Lock Module :

Linac module in the low-level RF system that provides RF input to the amplifier chain at the correct phase.

Frequency Control Module :

Linac module in the low-level RF system that commands the tuning slug controller in response to error signals that represent the difference between the transmission line RF phase and the cavity RF phase.

Front End :

A PDP-11 which gathers and transmits data for a given accelerator subsystem. The front-ends are interfaced to the MAC's or CAMAC crates on one side, and to the consoles or the VAX on the other. Examples include DEC-T for Tevatron devices, MR DEC for the Main Ring, ect.

Front End :

A PDP 11/34 computer that interfaces with a specific accelerator system, responsible for collecting data required by ACNET. The linac front end communicates with the primary microcomputer via an Ethernet link.

Front porch :

Portion of Tevatron ramp before flat top where bend field is held constant for a period of time.

Front Porch :

A flat top or region of constant magnetic field at an energy lower than the final peak energy to permit the beam to be extracted at two different energies. Beam is injected and accelerated to the level of the front porch, part of it is extracted, the remaining beam is then accelerated to full energy and extracted. Fixed target operation at Fermilab used to be at two different energies using the Main Ring. With all fixed target physics being conducted with beam extracted from the Tevatron this mode of extraction is no longer used.

FSEP :

Splitting septa in the meson line. It is called FSEP because it is located in the F1 manhole in switchyard.

FSHARE :

File SHARE. This is a process on the OPER VAX which coordinates and manages access to the Filesharing files for console and front-end programs.

-G-

G-10 :

A green glass-epoxy electrical insulator material used throughout the laboratory.

Gas :

A fluid with zero heat of vaporization (devoid of liquid). Denoted GHe, GH2, GN2, etc. 4

Gamma Function :

( g ) Related to the maximum divergence of the beam by

                                               "## 
                                               !ge 

Gamma Ray :

High energy electromagnetic radiation (photon, gamma ray) emitted in the processes of nuclear transition, particle annihilation, or charged particle acceleration.

Gannon box :

Another name for the NTF interlock module, built by Jeff Gannon.

GAS :

GHASP Advanced Software. A newer version of the GHASP protocol (see below) to which list processing and single-shot support have been added. GAS performs much of the software that would otherwise be done by the front-end. Usually information is exchanged between the front-end and an 080 module, but in the case of vacuum control the front-end talks to a 170 module.

Gas Barrier :

A ceramic insulator in the Linac 9-3/16" transmission line that isolates RF cavity vacuum from the nitrogen that pressurizes the transmission line.

Gate :

An electronic circuit capable of turning a device (usually a counter) on at a particular time and for a specified interval. It is usually used with fast logic devices to insure that certain conditions are met before counting can begin.

Gate Valve Controller :

A module in the preacc control room which shows the status of the 750 keV line vacuum valves and permits local control of those valves. Also the module at each cavity that monitors the ion pump power supply status and controls the vacuum valves at each end of the cavity.

Gateway Mode :

One of three modes of Linac control system operation where data requests and commands from the front end are serviced by the secondary microcomputers.

Gauss :

A unit of measure for magnetic fields. At 900 GeV, the Tevatron magnets produce a field of 39,600 gauss or 39 kilogauss.

Getter :

Material used to absorb residual molecules in vacuum spaces. Sometimes used in transfer lines.

GeV/c or GEV/C :

A unit of momentum appropriate to high energy particle physics. At kinetic energies much larger than the rest energy, the momentum of a particle in GeV/c is slightly less than the total energy in GeV.

GHASP :

General Host And Subsystem Protocol. A software protocol used for communication between a CAMAC front-end processor and intelligent subsystems, such as the microprocessors distributed around the accelerator.

Glitch :

A sharp increase/decrease and then immediate restoration of electrical power, often times causing devices to trip off.

Global Mode :

One of three modes of linac control system operation were data requests and commands from secondary microcomputers are serviced by other secondaries.

GPIB interface :

General Purpose Interface Board. An interface between a hardware device and ACNET. The interface is available commercially from Hewlett-Packard. Examples include spectrum analyzers and the DCCT current monitors for the antiproton source.

Gradient :

A measure of the electric field amplitude in an RF cavity. Usually expressed in percent of nominal.

Gradient Magnet Power Supply (GMPS) :

The power supply for the main Booster magnets.

Gradient Regulator :

Module in the modulator pulse-forming circuitry that acts to keep RF cavity gradient at the desired level.

Ground Fault :

A ground fault is the shorting of an electrical device or circuit to ground.

-H-

Hadron :

A particle which interacts via the strong force, either a meson or a baryon.

Hadron :

A particle which interacts via the strong force, either a meson or a baryon.

Haefely :

Trade name for a Swiss company that manufactures high- voltage equipment. In this application the high- voltage power supply that maintains the preaccelerator dome at -750 kV.

Half-duplex :

This is a data transmission scheme which is characterized by transmission in both directions in an alternate one-way-at-a-time fashion.

Half-high NIM :

A small NIM crate at each of the console stations in the MCR which contains hardcopy buttons, beam switches, console abort buttons, etc. Half-high NIM's are also used in other places.

Half-life :

The average time required for the amount of a particular radionuclide (radioactive substance) to be reduced to half its value as a consequence of radioactive decay. Like wise, the average time to decay for an unstable particle.

Hall Probe :

A hall probe is used to measure the strength of magnetic fields. When a magnetic field is perpendicular to a conductor carrying current, a potential difference is observed between points on opposite sides of the bar. A measurement of this potential difference gives the value of the magnetic field.

Halon :

A gas (CBrf3) used principally in computer fire protection systems. It can extinguish a fire by chemical decomposition at the combustion site without damaging the computer or injuring personnel.

Hard line :

A term that generally refers to a physical cable connecting two devices such as computers, control modules, repeaters, etc.

Hardcopy :

A paper copy of the image from the TV screen, Lexidata, Alarm screen, Storage scope, or Touch screen. A hardcopy can be either color or black and white.

Hardware :

Computer terminology referring to the physical components of a computer as opposed to the programs (software) used by the computer. Also used more generally to refer to the physical components of any system.

Hardwire loop :

Monitors the status of all interlocked doors and gates in an accelerator enclosure. If one is opened, the loop drops.

Harmonic :

An integer multiple of some fundamental frequency. Also, something expressible as a combination of sine and cosine terms. In Ham Radio parlance a Harmonic is known as a son or daughter of a Ham operator, as in "getting a lot of noise from harmonics"

Harmonic number :

The number of times the RF voltage oscillates during the time the beam makes one revolution around a circular accelerator. It also equals the number of RF buckets in the machine.

Harmonic # :

As used around the Accelerator division, harmonic refers to some multiple of the revolution frequency of the beam around a given accelerator. In the Accumulator, for example, the revolution time is H1.6 ms, hence the frequency is 1/1.6ms or about 625 kHz. The ARF1 frequency is about 52.8 MHz. The quotient of 52.8 MHz/625kHz is 84. This means (I think) that ARF1 operates at the 84th harmonic of the revolution frequency.

Head :

The pressure in length units (pressure/density) exerted by a fluid column or developed by a pump.

Heat Capacity :

The ability to absorb heat. Measured in units of Joules/gRK.

Heat Exchanger :

A device driven by temperature difference. Moves heat from a warmer fluid to the colder fluid through a common wall.

Heat Exchanger :

A device for passing heat from a working fluid (e.g. Main Ring magnet cooling water) to a reservoir or heat sink (e.g. Main Ring cooling ponds). Heat exchangers are also found in the satellite refrigerator buildings. These devices have an enormous range of forms and sizes depending on the application.

Heat Leak :

The enemy of things cryogenic. The inability to thermally isolate a given cryogenic system due to conduction, convection or radiation.

Heat of Conversion :

Heat required (or released) to change an equilibrium state. Ortho to Para Hydrogen for instance releases heat.

Heat of Fusion :

The heat that must be removed per unit mass to solidify a liquid at constant temperature.

Heat of Vaporization :

The energy required to cause a change of phase, liquid to gas, at constant temperature per unit mass.

Heavy Water :

Water in which Deuterium replaces Hydrogen, D20. The source which yields gaseous Deuterium(GD2) under electrolysis.

HELP facility :

Information which is readily available at a console on how to use a given applications program. The VAX cluster computers also have a help facility on many topics.

Hemorrhoid :

Beam Switch Sum Box chassis in MCR. So called because when it breaks down it can can be a real pain.

HEP :

High Energy Physics. Means particle physics research where the particles involved have extremely high energy. It's the real reason we're all here.

HERMES :

The process on the vax which displays messages on Channel 13.

Hertz (Hz) :

A unit of frequency equal to one cycle (repetition) per second (cps).

HFU :

Heater Firing Unit. Device which dumps current into the Tevatron magnet heater elements in the event of a quench. This action serves to spread the quench quickly which also spreads out the energy deposition.

Hi-Pot :

Hi-Potting is the subjection of a system to a high potential, low current power supply in order to detect a current leakage or ground fault. This is usually done to the Main Ring bus after an access to make sure the bus is not grounded by a tool, cable, or something else that might have been left touching the bus during the access. Hipotting can also be used to find the location of a ground fault if one is indicated. For example, in the Main Ring, about 1 kV is connected to the bus, and a current probe is used to sample the output to determine which direction the current is flowing, and thus the direction of the ground fault. An interaction of this process pinpoints the location of the short.

HIB :

HIBernate. A process scheduling state on the VAX. It signifies that a particular process is inactive. The process is present on the system and just waiting for a "wake up" call to start doing its thing. This is a very similar state to LEF.

High Beta :

see Beta.

High Rise :

Alternative name for Wilson Hall used among accelerator personnel

HLU Link :

A single continuous loop circling the Main Ring in a clockwise direction which transmits information from the House Logic Units. The signal originates in the PDC crate of MAC A and returns to the same card.

HOG :

Higher Order Generator. Device which controls and provides the output waveform for the power supplies which power the Tevatron quadrupole, sextupole, and octupole correction elements.

Hodoscope :

A group of particle detectors (usually scintillation counters) arranged to give accurate positional or directional information.

HOPS :

Higher Order Power Supply. Power supply for Tevatron quadrupole, sextupole, and octupole correction elements.

Horn :

A magnetic focusing device used to produce a more intense beam of neutrinos. Charged mesons from the target are focused by these horn shaped pulsed current sheets before they decay into neutrinos and muons, resulting in a more intense neutrino beam. Unlike a standard magnet focusing system, the horns can efficiently focus the meson beam over a wide momentum range.

Hourly :

Periodic tune measurements of a store done by the operators. The upper and lower tunes are measured. A data logger existence proof is run, and the T48 scheduler is checked to see if the flying wires were run.

Hydrogen :

The element from which protons are extracted for acceleration.

Hydrogen pump :

A centrifugal pump used to circulate liquid hydrogen (LH2).

Hyperon :

Heavy unstable (short-lived) particles. Hyperons all have half-integral spin (hyperons are fermions), are more massive than either a proton or neutron, include protons or neutrons as final decay products (hyperons are baryons), interact via the strong and electromagnetic interactions (hyperons are hadrons). Examples are the lambda, sigma, xi, and omega particles.

Hysteresis :

The phenomenon where the magnetization induced in iron or steel which is made to vary over time lags behind the magnetic field. This term is also used in general to indicate that changes in a system are dependent upon its past history.

Hysteresis :

(Dielectric) - Loss of energy caused by conversion to heat when the dielectric of, for example, a capacitor is stressed. (Magnetic) - Lagging of magnetization of iron behind the magnetic field intensity.

-I-

IAG :

Internal Assessment Group

Ignitron :

Device found in modulators used to dump the capacitor bank voltage in the event of a PA crowbar. An ignitron passes electrical current to a pool of liquid mercury at ground potential.

ILAMB :

Injection LAMBertson from 8 Gev line to Main Ring.

Impedance :

Opposition of a circuit to an alternating current, equal to the complex ratio of the voltage to the current in complex notation. The equivalent of resistance in a DC circuit.

Inclusive Reaction :

A reaction in which measurements are conducted on a specific subspace of the final state of particles and information on the remaining complementary components of the final state is disregarded. (e.g. p+p -> p+ "anything".)

Index page :

A list of applications programs available at a console. Each major accelerator system has a representative console program which displays this list. If no specific applications program is requested, the index page is displayed by default. Any program displayed on the list may be executed by interrupting under the program name or number.

Inductrol :

Voltage regulator for the Linac PA filament supply that compensates for variations in line voltage due to other large loads at the laboratory.

Inflector :

A magnetic or electrostatic device to apply a transverse force to a beam. Most often the term is applied to the pulsed septa which bend the injected beam onto the equilibrium orbit of a circular accelerator.

Injection :

The process of putting a beam of particles into an accelerator.

Injector :

Usually depends on context of system being discussed. When talking about Booster, it is the 200 Mev line. When talking about Main Ring it is the 8 Gev line or collectivly Pre-Acc, Linac, and Booster. With the plan to move Main Ring to its own enclosure the term injector has also come to mean the new Main Ring in its own enclosure which will be called the Main Injector.

Insulating Vacuum :

A vacuum provided for the express purpose of reducing gaseous conduction, usually <10-4mm Hg.

Insulation :

A means to reduce heat transfer. Conductive, radiated, or convected. 4

Integrated Luminosity :

The total number of collisions (collisions per second times the number of seconds).

Intensity :

Number of protons in the beam.

Interaction Length :

The interaction length is the mean distance a particle travels through a medium before it interacts with one of the target particles. Interaction as taken here is any effect of interest to the observer.

Interlock :

Something which constrains or inhibits a device, generally for the purpose of safety. There are temperature interlocks, electrical interlocks, radiation interlocks, etc. 1

Intermediate cylinder :

Cylinder inside of Main Ring RF cavity between the drift tube and outer wall. It is biased with a dedicated power supply.

Internal Energy :

Isolated system energy. DU = Q-W. see Enthalpy.

Internal Target Area (ITA) :

Obsolete term. Originally meant a long straight section in the Main Ring at CO where high energy physics experiments were performed. The Main Ring and Tevatron abort dumps are now located at C0. There is also an experimental detector area known as the Spectrometer Room adjacent to the C0 straight section.

Interrupt :

In an operational context it is usually the point at which a change is made or verified in the operation of a device or program. It is required for changes in the D/A of a device, to change pages on a console, etc. In a computer context it is a temporary break in the sequencing of a program initiated by events in the outside world.

Interrupt button :

A button next to the keyboard at each ACNET console which provides interrupt capability in conjunction with the selected applications program. The function is duplicated with the RETURN key on the keyboard.

Intertank Phase :

A signal that represents the difference in phase of two adjacent RF cavities in the linac.

Invert :

The time during the Main Ring or Tevatron ramp after flat top when the magnetic field is decreased rapidly. During this time, the outputs of some power supplies are inverted.

Invert :

To invert a power supply is to reverse its polarity at the end of a ramp to reduce the current at a rate exceeding the natural fall rate of the circuit. Only certain ramped power supplies such as the Main Ring supplies are designed to be inverted.

Ion :

An atom or molecule that is not electrically neutral but instead carries a positive or negative charge. 2

Ion Gauge :

A vacuum-measuring gauge that works by ionizing gas molecules with electrons and measuring the amount of ion current drawn to an anode.

Ion Pump :

A type of vacuum pump that works by ionizing gas molecules with electrons and catching the ions on a titanium anode. Used at pressures of 10-4 torr or less.

Ion pump :

Usually means sputter-ion pump. A vacuum pump in which pumping is achieved by ionizing gas molecules through collisions with high speed electrons. The ions are then captured on electrostatic plates. Permanent magnets around the pump increase the electrons' path length into a spiral and hence produce more ionization. This pump usually cannot be used at pressures much above 1 E-04 torr.

Ion Pump :

In an ion pump gas is removed by a combination of adsorption and ionization. Pumping by adsorption is accomplished by producing clean active metal surfaces within the pump. Molecules of the active gases are removed by reacting with these surfaces. Pumping by ionization is accomplished by ionizing the gas molecules, then accelerating them to be buried in the pump surfaces. Molecules of both the active and inert gases are removed by this action. The electrode material is usually titanium and the outside housing of the pump is stainless steel.

Ion Source :

The source of the protons to be accelerated, which is an electrical arc in hydrogen gas located in the high voltage electrode (dome) of the Cockcroft-Walton preaccelerator.

Ionization Chamber :

A particle passing through the gas in a small chamber forms ions. A voltage will cause the ions to be attracted to the collection plate, depending on their charge. As a result a pulse of current will flow for each particle that forms ions. Each pulse is proportional to the ionization energy delivered by the particle.

Ionization Gauge Controller :

One of two ion gauges in the preacc control room that monitor column vacuum and control the vacuum valves leading to the columns, as well as being interlocked inputs to the 750 keV chopper supply controllers.

IOMAC :

MAC Input/Output. A process that resides in the MR.BaRF front-end which is used for MAC to DEC communication. Operators usually see the term as an error message on the TV screen when there are communications problems with a given MAC.

IPA :

Intermediate Power Amplifier. An intermediate level of amplification in the Linac high-level RF system. The 400 W solid- state amplifier is the first IPA, and the 7651 tube is the second IPA.

IPE :

Index Page Editor. A program for enabling the programmer to make an applications program available from a console index page. Included is the capability of assigning a page number and title to the program.

IPPS :

Ion Pump Power Supply.

Isocenter :

One of two points in space defined by alignment fixtures in the NTF set-up and treatment rooms. Patient set-up is usually done on the premise that the area to be treated will lie at the isocenter.

Isoplane :

An imaginary plane perpendicular to the neutron beam axis and containing the isocenter. Used in NTF patient setup.

-J-

Jacketed :

Cryogenic devices that contain an outer covering to hold an insulating vacuum.

Jets :

Narrow clusters of subatomic particles resulting from collisions of quarks and antiquarks. The particles in jets are the objects actually observed in experiments such as those in the Collider Detector at Fermilab.

Johnson Controller :

This device is used to control the LCW flow through the Main Ring heat exchanger and magnets. This regulates the water temperature and pressure for the Main Ring magnets.

Johnson Controller :

Pneumatically controlled regulation system located next to the lcw heat exchanger in Main Ring service buildings which controls valves affecting the flow of lcw through the heat exchanger.

Joule :

A unit of energy J such that the heat capacity of water at 15RC is 4.18 J/gRC.

Joule Thomson Coefficient :

The Joule thomson coefficient, m, is defined as m = -Cp-1 (oH/oP)T = (oT/oP)H. The sign of m indicates weather a gas expansion will cause an increase or decrease in the temperature. If m is positive, the expanding gas will be cooled. The locus of points where m = 0 is called the Joule Thomson inversion curve.

JT :

Joule-Thomson expansion valve.

JT valve :

A cryogenic valve which cools the helium and nitrogen by allowing it to expand. They also serve to control helium flow. JT stands for Joule-Thompson.

-K-

KO Regeneration :

A neutral kaon beam consists of two states, KL ("K-long") and KS ("K-short") particles. The KS component decays rapidly, but can be "regenerated" when the remaining KL component is retargeted.

Kaon :

K-Meson. An elementary particle of spin 0 having a rest mass about 970 times that of the electron. It occurs in neutral, positive, and negative charge states.

Kautzky valve :

Cryogenic relief valve for Tevatron style magnets and spool pieces. They are kept closed under normal conditions by a constant pressure of helium gas.

Kelvin :

The Celsius unit with the constraint that absolute zero O zero degrees.

Kelvin Temperature Scale :

This scale uses the same degree interval as the centigrade (Celsius) scale but has an absolute zero. That is to say 0º kelvin is -273ºC. ºK=ºC+273.

Keyer :

A solid-state device providing the first stage of amplification in a linac modulator. The light-pipe input to the modulator is amplified to about 1 kV by the keyer.

Keylock Valves :

Beam line vacuum valves that are manually opened and closed to isolate beam pipe for maintenance.

Keyswitch Module :

Also known as the Pulse Shifter Controller Module. This module produces an HEP enable to be sent to the Pre- Acc prom module. Keyswitches on the front of the module selectively bypass beam switches in the MCR, as well as other inputs to the module.

Kicker magnet :

Very fast rise time magnet used to divert the entire beam at once. Typical uses are Booster extraction, Main Ring extraction, Main Ring and Tevatron abort.

Kinematics :

The description of the motion of particles and bodies without reference to the forces associated with that motion.

Kirk Keys :

Any keys that are captured by the lock they reside in. They are used in situations where a degree of safety is desired. Some are used to prevent a mechanical linkage from being manipulated unless the key is present in the lock. An example of this use is the Booster Brentford breaker switch arms. Others require another keys presence before they can be removed and used for access in another part of the system. An example of this use is accessing the Tev power supply DC breaker cabinet. The name Kirk comes from the company that makes the captured locksets.

Klixon :

A temperature-sensitive electrical switch used in interlock circuits of power supplies and magnets that opens when a certain temperature is exceeded.

Klixon :

A trade name for a heat sensor whose purpose is to protect other devices; it is used as an overtemperature interlock.

Knife Switches :

Single pole switches that connect individual Main Ring and Tevatron power supplies to their respective power buses. These knife switches are located in a cabinet on top of each Main Ring power supply. The Tev knife switches are located over the Tev dump switch. The knife switches have to be manipulated locally. The knife switches can be put in any of three states. They can be placed so that the power supply is racked in to the bus. They can also be placed so that the bus is shorted in the power supply effectively bypassing the supply from the bus. In the last state the knife switches are manipulated so that the bus is broke open at the power supply. This is done to facilitate highpotting a section of the bus in order to track down a ground fault.

Knob :

A wheel connected to a shaft encoder in the MCR capable of making a continuous change in the D/A of a device. This is generally located in the half-high NIM, bin on the right-hand side of the console.

-L-

Ladder Control :

Obsolete method of controlling quadrupole power supplies whereby the settings of a few supplies determined the settings for a number of others. No longer used.

LAM :

Look At Me. It is a flag used by many accelerator control cards to indicate a state. In other words, the device has information to be passed to the front-end and uses the flag to indicate to the front-end that it should read its information.

Lambda Particle :

A neutral elementary particle just slightly more massive than the proton. A hyperon member of the baryon family.

Lambda Supply :

A power supply which provides +5, -5, +15,and -15 volts. They are used to power Main Ring electronics in the service buildings.

Lambertson (magnetic septum) :

A special type of magnet having two vacuum chambers with one having a magnetic field and the other being field-free. They are usually found downstream of electrostatic septa.

Lambertson Magnet :

A special magnet used to separate two adjacent beams by providing a bending field for one beam and a field-free region for the other beam. A beam is usually separated into two adjacent beams upstream of a Lambertson magnet by a septum. The Lambertson magnet was designed at Fermilab and is named for its designer.

Laser printer :

Otherwise known as the Talaris T2400. One of the printing options residing in the computer room, accessible through the Development VAX. It is used for high quality prints. It has 300 dots/inch resolution and can produce up to 24 pages/min.

Latent Heat :

Heat of Vaporization. Units of J/g.

Latent Heat of Fusion :

The latent heat of fusion is the amount of heat required to melt a unit mass of a substance at constant temperature and pressure at temperatures above the triple point.

Latent Heat of Sublimation :

The amount of heat per unit mass required to vaporize the solid phase.

Latent Heat of Vaporization :

The amount of heat required to convert a unit mass of a substance from the liquid to the vapor state at a constant pressure.

Lattice :

The periodic relative arrangement of quadrupoles and drift spaces in an accelerator.

LCW :

Low Conductivity Water. Water that has had the free ions removed in order to increase the resistivity of the water to 9 MW/cm or greater. Found in the 55R and 95R systems used to cool linac components.

LCW :

Low Conductivity Water. It is deionized water which is used to cool magnets, power supplies, RF systems, etc.

Lead Flows :

Cryogenic cooling at the point where the warm Tevatron bus enters the cryostat. Liquid helium is allowed to flow from the single phase system out the feed can or power spool and around the bus to cool it down. When the Tev is at 90 Gev or 150 Gev the low energy lead flows are on leaking out a low rate of flow of single phase helium. When the Tev is ramped up to 800 Gev for fixed target or 900 Gev for collider operation the high energy lead flows are on leaking out a high rate of flow. When the Tev is not powered there is no need for cooling. If there is more lead flow cooling than is needed (having the high energy lead flows on when at 150 Gev) there is a possibility of ice balls forming around the leads. This can cause the LCW in the Tevatron bus to freeze and crack the LCW insulators.

Lead Glass Counter :

A Cerenkov Counter using dense lead glass as the Cerenkov radiator. It is sensitive down to very low velocities and therefore may be used as a total absorption shower counter for identifying electrons.

Leads :

see Power Leads.

Leak Detector :

A device for finding leaks in a vacuum system. The standard type for use in high vacuum systems is a mass spectrometer which can detect minute quantities of helium which is released outside the system at a suspected leak. The sensitivity of the leak detectors used in leak checking Tevatron components is one part in 10 billion.

LED :

Light Emitting Diode. These are used extensively for digital information display on control card front panels and elsewhere.

LEF :

Local Event Flag. A process scheduling state of activity for a given process on the VAX. It means that the process is waiting for a flag to be set before resuming activity.

Left Bends :

A set of large bending magnets that initially direct the beam toward the Meson Area. Also known as the MH- 200's.

Lepton :

A collective term for those spin 1/2 particles (Fermions) which do not undergo strong interactions. The word Lepton was coined from Greek root to indicate that these are light particles. The known leptons (e;, m;, ne, nm) are all lighter than the mesons and baryons.

Lexidata :

The commercial name for a color display screen available at all ACNET consoles. It is a medium performance display unit which generates a 640(H) by 512(V) pixel display refreshed at a non-interlaced 60 Hz rate to minimize flickering. There are eight colors which may be displayed on a pixel by pixel basis. These may be displayed directly or combined through one of three logical functions (AND, OR, XOR).

Light Link :

A light link is a light modulator/receiver combination used to carry control signals along a path across which a large electrical potential difference exists. The encoded control information crosses this high voltage region on either an optical fiber bundle or an air path.

LINAC :

LINear ACcelerator. It is essentially the first step in the acceleration process, bringing the beam energy to 200 MeV.

LINAC :

A linear accelerator for charged particles in which a number of electrodes are so arranged that when a voltage is applied at the proper radio frequency the particles passing through them receive successive increments of energy, sometimes described as riding a surf. The LINAC at Fermilab accepts protons from the Cockcroft-Walton preaccelerator at 750 kV, accelerates them to 200 MeV, and injects them into the Booster accelerator.

Linac 68k mP beam inhibit module :

Module in the preacc control room that sends the beam/no beam status to the linac secondaries, and causes a beam inhibit if one of the secondaries or the primary pulls the beam inhibit line.

Linac front-end :

A DEC PDP-11/34 which serves as the central node for the Linac controls system.

Linac Primary :

An Motorola 68000 microprocessor which initiates requests and gathers data on behalf of the Linac front-end. It is located behind Linac Station 6.

Linac Secondary :

Any of sixteen Motorola 68000 microprocessors which serve as local control stations in the Linac. There are separate secondaries for each of the nine Linac stations, one for each of the Haefelys a ground station for the Haefelys, and one each for the Buncher, Debuncher, 200 Mev equipment, and Station 10. The secondaries gather data and change the parameters of their associated equipment.

Linac Steering :

Procedure whereby beam is aligned at the head of the 200 MeV transport line by steering dipoles between tanks 6-7 and 7-8. Can be performed automatically by ACNET page L36.

Linear Voltage Differential Transformer :

LVDT. Also called Linear Variable Differential Transformer. Detects small position changes along an axis. They are used to detect position changes of Septa and Tevatron cryo valves among other places.

Link :

At Fermilab, links are the the systems of cables and repeaters which carry information to and from distant points in the accelerator.

Link Driver :

A device which organizes and transmits digital information on a link. In the context of the link drivers for the console and front-end computers this device performs a parallel to serial conversion on data to be transmitted on the link. It also acts as a receiver of data from the link and performs the reverse conversion.

Linlock Line :

Linac vacuum valve status input to the prom module and pulse shifter, powered by a small 5 volt supply at RF station 9. Vacuum valve controllers at each station short out the line whenever a valve closes, inhibiting beam.

Liouville's theorem :

A theorem from classical mechanics which states that for a beam with constant total energy, the area occupying a spatial coordinate and its conjugate momentum (q and p phase space) for each particle in the beam is conserved over time, although the shape and position of this region may vary.

Liquid :

The fluid phase with finite heat of vaporization and density greater than the gas phase. Denoted by LH2, LD2, LHe, LN2, etc.

Liquid Helium :

This is the coldest substance that is still a liquid and thus the only refrigerant at temperatures of a few degrees Kelvin and atmospheric pressure.

Lithium lens :

A device located directly downstream of the antiproton production target which acts to collect the secondary particles by reducing the solid angle of particles coming off of the target. The lithium lens could be looked at as a high gradient bi-planar quadrupole magnet. The lenses at Fermilab typically run at currents of hundreds of kiloamperes.

LLPA :

Low Level Power Amplifier. Linac 5-watt solid-state amplifier in the rear of the A5 racks that is the first step in the high-level RF system.

LLRF :

Low Level Radio Frequency. This refers to the electronics that provide the proper phase and frequency for the RF voltage. The LLRF controls the High Level RF Power Amplifiers which in turn control the electric fields in the RF acceleration cavities.

Local Mode :

One of three secondary modes in Linac where the secondary microcomputer satisfies data requests and commands from the local console.

Lock Out :

The process of placing locks on power supplies or power distribution panels so that the supplies can not be turned on or energized. This is a safety measure allowing maintenance to be performed on individual devices. It is also done to power supplies that feed electrical devices in the tunnel, such as magnets and correction elements, as part of the conditions for an open access. The locking and removal of power supply locks is taken very seriously at Fermilab. Unauthorized removal of a lock from a locked off supply is considered a safety violation and is grounds for immediate dismissal from the lab.

Logic loop :

An electrical relay loop that protects an accelerator enclosure by ensuring that no one can enter the area and reset the loop once inside. Once the logic loop has been dropped the interlocks must be reset in a specified manner on a search and secure.

Logic Unit :

A logic unit is the most flexible and useful type of coincidence circuit. Unlike the simple AND or OR circuits, it permits any logical combination of inputs to be required as an output.

          e.g. output = 1 AND 2 OR 3 AND 4-       1,2,3,4, = inputs. 1

Longitudinal Transit Time Factor :

Ratio of the energy gain of particle traversing a cell with a constant electric field to the energy gain of a particle traversing a cell with a sinusoidally varying electric field. Simple, no?

Loss monitor :

Diagnostic device which is used to measure the amount of beam lost from the vacuum chamber.

Low Beta Magnets :

Magnets used to focus the beam to create collisions of high luminosity. Low beta magnets are installed at both ends of the Collider Detector in the accelerator at B0 and D0.

Low Beta Squeeze :

After injecting protons and pbars into the Tevatron for collider operation a special set of quadrupoles are turned on at B0 to reduce the size of the beam and increase luminosity.

LSS :

Laboratory Services Section

LXCENT :

A process on the OPER VAX which saves Lexidata images in circular buffer files for recall at a later time.

LXPRNT :

A process on the OPER VAX that interfaces the color printer to the controls system to allow printing of Lexidata images.

Luminosity :

In colliding beams theory when 2 bunches of beam collide luminosity is defined as L=Nn/At; N=protons/bunch; n=antiprotons/bunch; A=cross-sectional area of intersection; t=time interval between bunch collisions. It can be considered to be the potential for particle interactions.

Luminosity :

A measure of the potential number of particle interactions for colliding beams. The luminosity depends on the intensity and phase space density of the interacting beams. The higher the luminosity is, the better it is for quark and Higgs hunters. The design peak luminosity of the TeVatron I project is 1030 cm-2sec-1. Integrated luminosity is measured in inverse nanobarns.

LUST :

Leaking Underground Storage Tank

-M-

MAC :

A Lockheed Electronics 16-bit minicomputer used for remote monitoring and control.

MAC-16 :

A parallel-processing 16-bit minicomputer once manufactured by Lockheed. They are used in some of the older systems, especially Main Ring, to interface between the front- ends and the equipment. All maintenance is performed by Accelerator Division personnel.

MAC Room :

A room under the MCR which houses a number of MAC-16 and DEC-11/55 computers which interface some of the front-ends to equipment in the accelerator. The MAC room also includes the most important clock generators and encoders as well as equipment for putting scope traces and intensities on Channel 13.

Machine Cycle Reset :

A signal, or clock event, to any specific accelerator to begin a programmed sequence of events. The major signals originate in the Time-Line Generator and are clock events encoded onto the Tevatron clock.

MACRO :

The assembly language for the DEC's. It is rarely used in applications programs.

MADC :

Multiplexed Analog-to-Digital Converter. At Fermilab, these are usually local stations capable of accepting up to 64 analog inputs and and converting each of them into a digital signal expressed in units of voltage. They consist of a single analog to digital converter with an analog input multiplexor to select one of the many possible input signals for conversion. Since only one channel may be digitized at a time, many commands are needed to digitize all possible input channels. This gives rise for the need of an MADC controller to coordinate its activities and issue the necessary commands. The Main Ring utility crates use a CC130 module while the newer CAMAC design is the 190 module. If each input to the analog mux is the output of a "sample and hold" circuit, then all the inputs may be sampled simultaneously even though the conversion must proceed sequentially.

MADC Volts :

The voltage output of an MADC, ranging from -10.24 V to +10.24 V. The least significant bit is 2.5 mV. The voltage represents a a twelve-digit bit pattern generated from an analog signal. Conversion factors to engineering units are kept in the System Database.

Magnet cage :

Caged-in area in the Transfer Gallery where a B1 dipole magnet, a B2 dipole magnet, an F-quadrupole magnet, and a D-quad are kept. These are electrically in series with their respective Main Ring buses and are used to monitor fields and currents.

Magnetic Field :

The field of force from a magnetic pole or surrounding a current flowing through a conductor in which there is a magnetic flux.

Magnetic Monopole :

The magnetic monopole conjectured by Dirac is the counterpart of the electric charge. Analogous to electric monopoles, like magnetic monopoles would repel and oppositely charged magnetic monopoles would attract. As of this date there is no evidence supporting the existence of magnetic monopoles. 1

Magnetic tape :

A system for storing digitized information. Fermilab examples include the TU77, TA78, and TU78 tape transports in the Accelerator computer room.

Magnetron :

Ion source that produces negative ions by extracting them from a plasma formed by an electric arc formed in hydrogen gas. Used in the Pre-Acc H- and I- sources at FNAL.

Main Collimator :

NTF collimator assembly following the primary collimator and containing inserts to shape the neutron beam to the desired size.

Main Control Room :

The area at Fermilab located in the Cross Gallery where acceleration of the beam of protons is monitored and controlled.

Main Ring :

Accelerator which takes the proton beam at 8 Gev and increases its energy to 150 Gev for injection into the Tevatron (fixed target operation mode).

Main Ring Abort link :

A hardwired link originating in the back racks of the MCR and sent around the ring via 200 modules in the utility crate of each service building. The signal is continuous until certain parameters go out of tolerance, at which point the link is broken and the abort sequence is initiated.

Main Ring Power Supply (MRPS) :

Power supplies for the Main Ring magnets. They are turned on sequentially to form the Main Ring ramp.

Main Ring Sample Time :

The time, once a cycle, during which the sample and hold modules are loaded before information is sent back to the MCR.

Mainframe :

The cabinet or piece of equipment in a computer system which contains the cpu. The term also refers to the type of computer which requires a mainframe; i.e., a large computer.

Make Up Water :

The process of replacing lost LCW or coolant for a particular cooling system.

Manchester coding :

This is a coding scheme for digital information on a high frequency RF carrier. It is used by the Tevatron clock, the Linac serial link, and other systems. For example, TCLK operates at a 10 MHz rate, and byte-sized signals can be sent out at a 1 MHz rate. That allows for 10 100-nsec frames. The clock is structured so that if a phase transition takes place in the middle of a frame, it is interpreted as a "1"; otherwise, it is interpreted as a "0". Being a "self-clocking" mechanism, time errors do not accumulate as clock events are superimposed on the pattern. There is also a start bit (0) at the beginning of each clock event and a parity bit at the end. The 10 MHz pattern is transmitted around the accelerator on an RF carrier frequency of 50 MHz, and is demodulated and retransmitted at each house.

Manchester (encoding) :

System of data encoding on a bipolar clock used in serial data link communications.

Manhole :

A physically isolated section of accelerator tunnel.

Manual disconnect :

Large switch on a power supply cubicle which can be used to disconnect the power supply (actually the primary of its transformer) from the feeder.

MARS :

Main Ring Automated Ramp Start up. This is a computer program currently found on page M10 that automatically starts the Main Ring ramp.

Mass :

A quantitative measure of a body's resistance to being accelerated.

Master Oscillator :

Oscillator that provides the RF signal for all linac RF systems. Typically runs at 201.24 MHz.

Matching :

The process of tailoring the emittance of a beam to the acceptance of a device.

Matter :

The substance of which a physical object is composed. All materials in the universe have the same inner nature, that is, they are composed of atoms, arranged in different (and often complex) ways; the specific atoms and the specific arrangements identify the various materials.

Maximum Working Pressure :

MWP. Pressure beyond which a pressure container should not be operated.

MCCR :

Main Control Room Relay Rack

MCR :

Main Control Room. The locus at which most of the information on the ACNET system is received and acted upon. A number of hardwired signals are available as well. The MCR does not control the experimental areas or the beam lines leading directly to them.

MDAT :

Machine DATa. It transmits around the accelerator the programmed values for the Tevatron current and dI/dT, the measured values for the Tevatron current and dI/dT, and the measured Main Ring current. MDAT is carried on one of the 19- conductor cables at a 720-Hz rate. This information is then decoded and used by several devices such as the ramped correction elements.

MDAT link :

The link which communicates Tevatron ramp current information around the ring. MDAT stands for Machine DATa.

MDC :

Multiplexed Data Channel. A MAC 16 option which allows communication with up to 16 external devices independent of program instructions (Direct Memory Access) and is capable of transfer rates up to 330 K words/sec to or from memory. Communication is interleaved between processor execution of instructions and shares the PDC I/O lines. The program must specify a device, destination in memory, and a transfer count before a transfer may begin. The processor is free to resume program execution during the actual I/O. When the specified number of words has been transferred the MDC hardware interrupts the CPU.

MDC Link :

The link consists of two independent cables which perform block data transfers. Data may be transmitted in either direction, originating at MAC-A or any utility crate, but currently only the crate to MAC-A direction is implemented.

MDV :

MoDulator View. RF abbreviation. This is the output voltage of the modulator that supplies anode voltage for the final tube of the power amplifier. There are two types of modulators. The originals that are calibrated for 1 V input equals 2,500 V output and some that have been modified for 1 V in equals 3,000 V out.

Mechanical Phase Shifter :

Device strung between Linac RF cavities with inputs from each cavity which produces the intertank phase signal used for phase regulation.

Medical Microcomputer :

NTF computer that drives the NTF console and interfaces with the beamline microcomputer.

Melting Point :

Any of the points along the solidus line in the P-T phase plot. Most often quoted at one atmosphere.

Meshall :

The large concrete pre-target enclosure in the Meson Area providing access to the target train for inspection and minor maintenance. Meshall also contains beam diagnostic equipment and beam line magnets. The primary Meson Area target is positioned in a heavily shielded tube just downstream of Meshall.

Meson :

One of a class of medium-mass, short lived elementary particles with a mass between that of the electron and that of the proton.

Meson :

A member of the class of short lived, elementary particles having rest masses between that of the electron and the proton. Mesons are bosons, i.e., have integral intrinsic angular momentum. Examples: pi-mesons (pions) and K-mesons (kaons).

Metering Resistor :

Precision resistor-capacitor network used for measuring the voltage on the preaccelerator dome. 2125 MW.

Microprocessor :

A cpu contained on a single integrated circuit chip. Microprocessors commonly used at Fermilab include the Motorola 68000 and Zilog Z80 and Z8000.

Mil :

Unit of measurement equal to .001". This is not to be confused with a millimeter.

MIL-STD-1553B :

Digital multiplex data bus standard used for interface between secondary #G and Eurobus crate cards that control the Haefely power supplies. Originally developed by the U.S. military.

Milliamp :

A unit of current measurement. 1 thousandth of an amp. In the Antiproton Source it is used as a unit for quantifying beam intensity in the Accumulator.

Millirad :

1/1000 of a rad. The rad (an acronym for Radiation Absorbed Dose) is defined as that quantity of radiation that delivers 100 ergs of energy to 1 gram of substance.

Milliradian :

A unit of angular measurement. 1/1000 of a radian or about 0.057 degrees. Milliradians are often used when discussing the amount steering a magnet does to a particle beam for a given magnet current.

Millirem :

1/1000 of a rem. The rem (an acronym for Roentgen Equivalent Man) is a biological rather than a physical unit of radiation damage. It represents that quantity of radiation which produces the same biological damage as 1 rad of x-rays or gamma radiation.

Min/Max :

The limits of tolerance for a particular device. An alarm (and sometimes a beam inhibit or abort) is generated when the value of the device falls outside these limits.

Mini Straight :

see Mini Tube

Mini Tube :

Short beam pipe immediately downstream of a Main Ring quadrupole around which correction elements are located. This is also where the BPM detectors and other beam diagnostics are usually are located. The term mini-straight is sometimes used in place of mini-tube.

Minicomputer :

A low-cost computer with a limited processing capability which is used for the more routine functions in a system. The PDP-11's are minicomputers used extensively at Fermilab.

Minimum Ionizing :

A charged particle traveling through matter near the velocity of light loses less energy per unit path to the atomic electron than a slower particle and is hence minimum ionizing. Above the velocity of minimum ionization there is a gradual (logarithmic) rise in ionization loss for extremely relativistic particles. Minimum ionization for protons is in the range from about 2-10 GeV.

Mixer :

Final component in Linac low-level RF system that passes the RF signal to the amplifier chain when gate signal arrives from waveform generator/sequencer.

Mod Block :

Premature termination of a Linac modulator pulse triggered by a modulator current of greater than 400 amps during the pulse.

Modem :

A device which translates computer signals into a format which can be transmitted over telephone lines. There are some controls personnel who have modems at home through which they can talk to Fermilab computers.

Modulator :

High-voltage device connected to the anode of the PA that controls the RF output to the cavity.

Modulator Regulator :

Module that regulates modulator current to maintain constant RF cavity gradient.

Mole % :

Describes the mixture in molar percent. In the Tevatron cryogenics system it is used most often in reference to the NeH2 mixture.

                                               2 atomic % Ne 
                                   Mole % Ne = ############### 
                                               atomic % Ne + 1 

Momentum Compaction :

A function which describes the deviations from the equilibrium orbit due to momentum error in the beam. Generally denoted by ap

Momentum Dispersion :

Spread in momentum due to the bending of particle of different momenta passing through a dipole.

Monitor/Control Module :

Module in the preacc control room that monitors voltage on the preaccelerator dome, digitizes it, and sends it along with the command voltage to the regulator/oscillator module to complete the voltage regulation feedback loop.

Monitor/Inhibitor Module :

Linac module that oversees a number of RF system interlocks and inhibits the modulator pulse if conditions warrant.

Monitor Unit :

Artificially-derived unit used by NTF to define neutron dose rates.

Monoatomic :

Single atom molecules. Ex. He, A, Kr.

Monte Carlo Calculation :

Any method for obtaining a statistical estimate of a desired quantity by random sampling. The sampling is made from an artificial population that is in some sense a model of the physical system being investigated.

MOU :

Memorandum Of Understanding

Mountain range display :

An oscilloscope plot, usually generated in the MRRF building, which displays bunch structure vs. time. The value of this type of display is that it can be triggered at some frequency to show information (such as bunch structure) for a set number of triggers, with each trigger having a different vertical offset. If the frequency is chosen to be the revolution frequency, one can watch the time evolution, within a window, of the same bunch as it circulates in the accelerator.

MRBS clock :

Main Ring Beam Sync clock. It operates at about a 7.5 mhz rate, so that there are exactly 159 clock ticks per turn. It is used wherever synchronization to the beam has to be especially accurate.

MRRF MAC :

A MAC-16 computer located in the MRRF building which provides digital control of the RF stations.

MSDS :

Material Safety Data Sheet

MULT:n :

A collection of two or more devices for which their D/A values can be changed in specific ratios to each other; n represents the number of devices.

Multibus :

IEEE standard format for microcomputer systems hardware.

Multibus crate :

A set of standard signal lines used to interconnect the modules of various microprocessors, such as the Z80 and Motorola 68000. Physically it is a backplane which the modules plug into. The Multibus crate is capable of supporting twenty address lines, sixteen bidirectional data lines, and eight parallel interrupt lines, as well as bus control signals, data control signals, and power distribution lines.

Multipactoring :

An electron multiplication phenomenon observed in RF cavities when the fields between nearby metal surfaces is such that an electron originating on one surface can cross to the other surface in exactly one-half period of the RF. These electron beams can destroy parts of the cavities if not suppressed. Fortunately, there is a relatively narrow voltage range where multipactoring can occur, so the voltage can be stepped through this region rapidly.

Multiplex :

A system where one output channel can be selected from among many input channels.

Multiplexing :

A means of transmitting several independent signals over the same transmission line by separating them in time or frequency.

Multiplicity (special usage) :

The number of particles produced from a single collision.

Multiturn Injection :

A technique of introducing beam into a circular accelerator over a time greater than the circulation period of the beam by moving the equilibrium orbit at the injection point so that the injected beam just misses the injection septum at the end of its first turn.

Multiwire :

A device consisting of many (@ 24) thin wires stretched across an opening in a paddle. This paddle can be rotated into the beam and each wire will produce an output signal proportional to the number of particles it intercepts. These signals are plotted by a computer to create a beam profile.

Muon :

A charged elementary particle having a mass about 207 times that of the electron. It decays into an electron and two neutrinos.

MUX :

Multiplexor. It is a device which receives inputs from a number of sources but outputs only the one selected by the user.

MV :

Manual Valve.

-N-

Narrowband Train :

One of the target train systems in the Neutrino Area. It provides a momentum selected dichromatic neutrino beam (neutrinos of mainly two energies) and is compatible with operation of the muon beam N-1. "Narrowband" refers to the peaking of the neutrino beam intensity at two energies as opposed to a neutrino beam composed of a wide range of energies ("broadband").

NBP :

Normal (atmospheric) Boiling Point. A fluid temperature.

NBS Clock :

National Bureau of Standards Clock. There are two of these clocks in the MCR. One of these arrives via a WWV signal broadcast from Boulder, Colorado. The other is transmitted via satellite.

NEC :

National Electric Code

NEPA :

National Environmental Policy Act

NERP :

National Environmental Research Park

NETPROCESS :

NETwork Process. Another name for ACNET. It is a process on the VAX which manages communications between nodes.

Neuhall :

A large concrete enclosure comprising the pre-target area of the Neutrino Area. The target trains may be pulled from the target tube into Neuhall for inspection and minor maintenance. Neuhall also contains beam diagnostic equipment, beam line magnets, and sometimes a small scale experiment.

Neutral Current :

The first evidence of neutral current interactions was the observation absence of a charged muon in the final state of the reaction nm + p -> nm + hadrons in which no muon appears in the final state. The theoretical necessity of neutral currents emerged as a result of the attempts to renormalize the theory of weak interactions so as to cure its divergence at high energies.

Neutrino :

An electrically neutral particle of very small (probably zero) rest mass. Neutrinos and antineutrinos can penetrate the earth without appreciable attenuation. Two types of neutrinos exist, one associated with electrons and the other associated with muons. It is currently believed that neutrinos interact only by the weak force.

Neutron :

An elementary particle with no charge and a rest mass slightly greater than the proton rest mass. The neutron is a spin 1/2 fermion. It is one of the basic constituents of the atomic nucleus. A free neutron decays with a half life of 12 minutes into a proton, an electron, and a neutrino (beta-decay). The neutron and proton are sometimes considered in nuclear physics to be differing charge states of the nucleon.

NFPA :

National Fire Protection Agency

NIM :

Nuclear Instrumentation Module. It is standard crate equipment, with a defined protocol, for some devices in the accelerator. "Half-high" NIM crates are used in the MCR and Pre- Acc control room. Other NIM crates are used in the MRRF building. The "half-high" crates in the MCR are only used for power and the modules do not communicate with each other.

NIMBIN :

A rack mounting receptacle for electronic instrumentation modules standardized according to the NIM (Nuclear Instrumentation Module) system. It uses standardized rear connectors and serves a similar function to a CAMAC crate.

NMR probe :

A Nuclear Magnetic Resonance probe used to accurately monitor magnetic fields. Among other places it is found in magnet cage magnets and the LINAC spectrometer magnet.

NO Q :

An error code generated when a GAS-speaking module, such as an 080 or 170 card, fails to "return Q", which is part of the communications protocol. No Q indicated data is not yet available for reading.

NO X :

An error code generated when a CAMAC module fails to acknowledge its function codes. It can mean that the user is trying to address a nonexistent module or that an incorrect address is being used or the module is busted.

Node :

A processing point in a network of computers. For example, A VAX 11/785 is the central node of the ACNET system.

Nominal :

The desired A/D value of a device, as defined by the user. For alarm purposes there is also a defined tolerance, or min/max value which brackets the nominal value.

Notch Filter :

Notch filters as used in the Stack Tail Dp/p cooling system act to suppress signals at frequencies which correspond to harmonics of the revolution frequency of the p-'s in the core. If the stack tail momentum system is allowed to act on the core, beam heating results (not good). Notch filters also assist in shaping the gain vs. momentum (frequency) in the stack tail. I think this means that the filters help to provide the correct gain to the stack tail cooling kicker electrodes as a function of where particles are in the stack radially, which corresponds to the momentum of the particles.

NTF :

Neutron Therapy Facility, a medical facility investigating the treatment of malignant tumors with neutrons. Neutrons for the facility are generated by steering 66 MeV ions from the linac into a beryllium target. Once called CTF, Cancer Treatment Facility.

NTF Beam Control Module :

The module in the NTF control room that actually initiates beam when two switches on the front panel are pressed simultaneously.

NTF Interface Module :

Modules located at RF systems 3 and 4 that sense the time of the RFON pulse. The module at system 4 will send an RF4 INHIBIT to the NTF interlock module if the RFON pulse at system 4 does not shift at the proper time.

NTF Interlock Module :

Also known as the Gannon box. This is the locus of all the NTF interlocks. The logic for producing an NTF enable is contained in this unit, which then sends the enable to the prom module. The interlock module also drives the status modules in the NTF control room and the MCR.

NTF Status Module :

Module that shows the status of the NTF interlocks, generated by the NTF interlock module. The module in the MCR also has keyswitches and toggle switches that are themselves part of the interlock chain. The module in the NTF control room has status only.

NTP :

Normal Temperature and Pressure. 70ºF and 14.696 psia.

-O-

O-ring :

A vacuum seal of circular cross-section, usually made of Neoprene, which provides a seal between two parallel surfaces. It usually rests in a machined "O-ring groove" in one of the surfaces.

Object :

Optical term referring to one focus of a dipole magnet. Parallel beams entering a dipole will cross at the object.

Octupole :

A magnet with eight pole faces used for correcting dipole magnetic field errors. Octupoles also play a role in Tevatron extraction.

ODDMOD :

Accelerator statistics gathering hardware. Feeds the statistics data to the VAX. If handshaking is interrupted, ie. VAX dies, then ODDMOD continues to collect data. The Datalogger on the other hand is a program resident in the VAX. When the VAX dies, it dies and no statistics are gathered. ODDMOD was designed as a way to avoid the interruption of data gathering. The module was designed by Todd Johnson and was originally called the Todd Module. A parameter involving TOD MOD was made called T:ODDMOD. Eventually the name permutated to ODDMOD.

ODH :

Oxygen Deficiency Hazard. In areas where the cryogenic system is used a cryogen leak can displace Oxygen creating a hazard to personnel. This necessitates the implementation of special safety procedures and Oxygen monitoring equipment for working in designated ODH areas.

Off Tube :

One of two Linac thyratrons that control the operation of a 750 keV chopper. After the on tube fires, the off tube fires to ground one side of a series capacitor and draw one of the chopper plates from ground to a negative potential.

On Tube :

One of two Linac thyratrons that controls the operation of a 750 keV chopper. The on tube fires to bring one of the chopper plates from a high potential to ground. The off tube fires at a later time.

Operational VAX :

The VAX 11/785 in the computer room designated for operational use. This computer acts as the central node for the ACNET system. It handles the data base and alarm reporting, and retains the applications programs to be written onto the console disks when necessary. Either VAX1 or VAX2 may serve as the operational one if the proper connections are made. Currently, VAX3 may not be configured to be the OPER VAX.

OPERATOR (Account) :

An account on the operational VAX which allows operators to perform certain rebooting tasks and other functions on the ACNET system.

Optical Isolator :

An element in an electrical circuit that converts a signal to a light pulse at one point in the circuit and then back again in another in order to isolate the grounds of each part of the circuit from each other.

OPTO22 :

Device which converts a binary signal to a light pulse. Found in the red dot binary I/O boards in the linac secondaries.

ORBIT :

An applications program run partially on the operational VAX which "smooths" the Tevatron beam orbit by making adjustments to the correction dipoles. The program has many other functions all associated with controlling the beam position. Another program exists, called ORBIT Jr, which performs some of the same functions but runs entirely on the console computer.

Orbump :

A pulsed magnet system in the injection section of the Booster. It moves the injected H- beam from the 200 MeV line and the circulating proton beam in Booster so that they overlap and pass through the stripping foil. This allows the Booster to accept and stack up to ten complete turns.

ORC :

Operational Readiness Clearence from Research Division

Ortho Hydrogen :

The product of normal hydrogen liquification. Not in equilibrium at liquid temperatures. Characterized by "ortho" ( || ) electron spins. Often referred to as "noral" hydrogen.

Oscilloscope :

An electronic instrument for displaying on a fluorescent screen waveforms from electrical signals.

OSHA :

Occupational Safety and Health Administration

Overcurrent :

A power supply turn off (e.g., blown breaker) in response to drawing too much current.

Overcurrent Trip :

See Fast Trip

Overpass :

Section of Main Ring which is used to vertically bypass a colliding beams region. There is presently one at B0 and one at D0.

Outgassing :

When a beam line or device is under vacuum, any oils or moisture in the device has a lower vapor pressure and evaporates. This is known as outgassing and spoils vacuum making it difficult for the device in question to pump down to operating vacuum levels. For this reason it is necessary to ensure that vacuum devices are exceptionally clean on the inside before they are used.

-P-

p- (pbar) :

The symbol for antiproton. p is physicists' shorthand for a proton. A bar atop a symbol denotes that particle's anti- counterpart. p- therefore is representative of an antiproton.

PA :

• 1) Primary Application in the ACNET environment.
• 2) Power Amplifier.

PA Crowbar :

Linac RF system trip that occurs when the modulator current is greater than 600 amps during the RF pulse or 125 amps between pulses. A PA crowbar fires the permanent inhibit, shorts the capacitor bank to ground through the ignitron, and resets automatically after 30 seconds.

Page fault :

This is a term used to describe the dynamic memory allocation of an executing process on the VAX. In a virtual memory system (see VMS) only part of the information being processed is within physical memory. The remaining information can be assigned to the disk. When the process requires more space than is available in dynamic memory, the memory is broken into pages consisting of 512 contiguous bytes. A "page fault" is the process of exchanging pages between the disk and dynamic memory.

Pagoda :

The Pagoda was the main control and tuning area in the Proton Area built in a shaped inspired by an oriental pagoda. Control and tuning is now done by the SOD Operations Center control room. The Pagoda is no longer used. The basement area underneath still has a few power supplies and control diagnostic racks.

Paint can :

A beam loss monitor used in Booster and Main Ring, and consisting of a light-tight can filled with scintillator fluid surrounding a photomultiplier tube. The real time signal produced can be used to measure spill structure.

Paint Can :

An inexpensive radiation detector consisting of a simple (non multiplier) phototube mounted through the top of a one pint paint can full of liquid scintillator which produces light in response to ionizing radiation. Because of their low sensitivity these detectors are suitable for primary beam areas like the Main Ring tunnel.

Pair Production :

The conversion of a photon into an electron and positron when the photon traverses a strong electric field such as that surrounding a nucleus or an electron. Pair production is one of three distinct processes by which a photon can effect the emission of an electron from matter, the other two processes being the photoelectric effect and the Compton effect.

Para Hydrogen :

The equilibrium condition at liquid hydrogen temperatures. Not in equilibrium at ambient temperatures. Characterized by "para" ( |~ ) electron spins.

Parallel data :

In terms of data transmission it means that all bits of a character or byte are transmitted simultaneously. This requires a multiconductor cable or bus with each conductor carrying a single bit. A 16 bit word requires 16 conductor cable for transmission.

Parameter page :

Any of a number of pages with a standard format listing devices on the ACNET system. The device mnemonics, descriptor texts, D/A settings, and A/D readbacks appear on the screen when the page is first called; MADC voltages, HEX values or MIN/MAX tolerances may be substituted for the A/D readbacks by using the touch panel. Parameter pages also support a standard fluid surrounding a photomultiplier tu plotting package allowing four devices each to be displayed on the 613 storage scope and the Lexidata, and the capability of copying each of the screens at an ACNET console.

Parasitic :

Any activity being carried out which is not the top priority at that time. Parasitic activities are supposed to be carried out with minimal interference to the top priority activity.

Particle :

A small piece of matter. An elementary particle is a fundamental constituent of matter. Quarks and leptons now appear to be the only elementary particles but the term is often used in referring to any of the subnuclear particles.

Parton :

Obsolete term for hypothetical point like constituents of nucleons (protons and neutrons). Partons have since proved to be quark particles.

Pbar :

Fermilab slang for antiproton. Used most often in conjunction with the Antiproton Source.

Pbar Target :

see Target

Pbar Shot :

The injection of antiprotons from the Accumulator into the Main Ring and on into the Tevatron in preparation for colliding beams operation.

Pbar Stack :

see Stack.

PDC :

Programmed Data Channel. The MAC-16 includes a set of data, address, and command lines that provide parallel communication (by 16 bit words) between the cpu and external devices. This I/O is controlled by program instructions (as compared with MDC I/O). I/O rates via the PDC depend on the amount of additional processing necessary in the program. The maximum data rate is about 60 Kwords/sec. A PDC transfer may be performed to one of up to 255 external device addresses.

PDC Crate :

An I/O interconnection scheme intended to allow simple interfacing of external devices to a MAC-16's PDC I/O lines. The hardware looks like a CAMAC crate but the internal line designations are definitely not CAMAC. They have been defined to make the crate a buffered fan-in/fan-out for the MAC's PDC bus. The MAC communicates with and controls the crate through two crate modules (the PDC BOX COMMAND BUFFER and the PDC BOX DATA BUFFER). All of the interface modules have been designed and built by Fermilab personnel.

PDP 11 :

A computer manufactured by Digital Equipment Corporation with 20K of memory. As of 1991 most of the control room consoles are driven by PDP 11 computers. There are plans in the near future to replace these consoles with MicroVAX workstations. PDP stands for Programable Data Processor.

PDP-11/34 :

Low end minicomputer made by DEC. These 16-bit computers are currently used as the console processors, and one serves as the Linac front-end. These are UNIBUS based machines. Each is equipped with 124 Kwords of MOS memory, a floating point processor, cache memory, and an RL02 disk system.

PDP-11/44 :

A UNIBUS-based minicomputer built by DEC which contains a separate memory bus capable of holding up to four Megabytes. PDP 11-44's are used for many of the front-end processors.

PDP-11/55 :

A medium-performance 16-bit minicomputer formerly built by DEC which uses bipolar memory to speed processing. There are three 11/55's (DEC B, DEC C, and DEC D) in the MAC room. The first two are used for Main Ring power supply control and regulation and the third for development and as a spare.

PDC Crate

PDP-11/84 :

The newest and fastest of the PDP-11 series. They are UNIBUS-based. The processor is on a single J11 chip. The 84's are used for the fastest front-end processors.

Peaking Strip :

An instrument used for magnetic field measurements. It measures the voltage pulse induced in a coil surrounding a sample of magnetic material when the direction of the magnetization is reversed.

Pearlite :

A finely divided powder used to insulate when vacuum failure is a serious consideration or the super insulation costs cannot be justified. 4

Penetrations Key :

Key that opens the lock on penetrations that lead into tunnel where beam travels. Most often implies the Key to the LINAC penetrations.

Periodic Interrupt :

This is a software term used to describe an aspect of program execution timing. For example, all of the console computer processors have a 15 Hz interrupt which signals the APM, and hence the applications program, to execute some section of code at this rate.

Permanent Inhibit :

Linac RF system trip caused by four successive mod blocks in a row. A permanent inhibit shuts off the modulator pulse and shuts down the high-voltage power supply for the capacitor bank.

PEX box :

Essentially an extension of a PDP-11 console computer or front-end which consists of UNIBUS cards. All PEX boxes have a standard set of cards, including a Universal Clock Decoder and PIOX/PIOR interfaces. The PEX boxes for the front-ends include additional cards for interfacing to the outside world.

PFX :

Procedures For Experimenters

Phase Advance :

A measure of the stage of the betatron oscillation at some point around the accelerator; usually denoted by the greek letter psi.

Phase Comparator Mixer :

An element of the low-level RF systems that looks at the relative phases of two RF signals and produces a signal proportional to the difference in phase.

Phase Diagram :

Phase diagrams indicate the boundaries between the solid liquid and or gas phases of a material for a given pressure or temperature.

Phase Lock Input :

Output of a Linac phase comparator mixer that looks at the desired RF phase and the cavity RF phase. This signal is raised by 5 volts to produce phase lock output.

Phase Lock Output :

Signal proportional to the difference between the desired RF phase and the cavity RF phase, used to drive a phase shifter that compensates for shifts in cavity RF phase due to beam loading.

Phase Reversal :

A method of encoding data on a clock where the shifting from one level to the other is shifted in phase for a number of cycles. The number of cycles for which this reversed phase exists constitutes the data being transmitted.

Phase Space :

A six-dimensional space consisting of a particle's position (x,y, and z) and divergence (x-prime, y-prime, and z- prime). Phase space is generally represented in two dimensions by plotting position on the horizontal axis and and the corresponding divergence on the vertical axis.

Phase Space :

A six-dimensional space consisting of position and momentum in each of three orthogonal directions.

Phase Space :

Phase space is an abstract space having a dimensionality equal to six times the number of particles in a system. The state of a system is represented by a system point whose components are vectors of the particles. The acceptance of an accelerator is simply the volume in phase space comprising the coordinates and momenta of all particles that will not be lost in the course of subsequent acceleration.

Phase Stability :

Phase stability enables particles to be accelerated to their final energy. The voltage waveform for the accelerating electric field is sinusoidal. Particles in an accelerator do not advance side by side but are spread out into a column. Therefore if the front end of such a column reaches the accelerating gap when the voltage is at its maximum all later particles experience less voltage and thus less acceleration. Consequently the column lengthens and ultimately many of the particles are decelerated because they arrive at the gap when the electric field is directed in the opposite way. If the phase f of a synchronous particle (frequency of RF = frequency of revolution) is within certain limits then the accelerating voltage can accelerate particles that enter the gap with f Df thus giving a stability. However, if f is outside these limits the RF gets "out of step" with the particles preventing acceleration to the desired full energy.

Phase Stability (principle of) :

The principle which gives the range of momenta which can be accelerated in a synchronous accelerator.

Photomultiplier :

An electronic tube which generates an electrical current roughly proportional to the light intensity impinging on the tube. Photomultiplier tubes are typically used to measure small light signals from a scintillator or Cerenkov counter through which charged particles have passed.

Photon :

A quantum (bundle) of electromagnetic radiation. Its energy is proportional to its frequency, and it has a spin of 1 (is a boson).

Pickup Loop :

In Linac a small (1/8" square) loop at the end of a coaxial cable that is driven by the RF cavity magnetic field to produce a signal proportional to the electric field in the cavity.

Piezoelectric Crystal :

A symmetric crystal that bends when an electric potential is applied to it (or vice versa). Used in the Pre-Acc ion sources to regulate the gas flow into the source. A piezoelectric crystal is also the heart of a crystal oscillator, such as the master oscillator.

Pig Gauge :

Means a penning gauge, Phillips gauge, or cold cathode gauge, all of which work on the same principle. Electrons are produced by a cold cathode and accelerated toward a high voltage anode, ionizing gas molecules. The ionization current is measured and converted to a pressure readout.

Pig Gauge :

Penning Ion Gauge. A type of ion gauge used to measure vacuum and control valves in the 200 MeV area.

Pinged Beam :

A small time slice separated from the slow spill (by a pinger) to give a spill of <100 msec for use with a bubble chamber, for example.

Pinhole Magnet :

A special pulsed magnet in the extraction line at Fermilab designed to prevent pinged beam from reaching the Proton and Meson experimental areas.

Pion :

Pi-Meson. A strongly interacting elementary particle of spin 0 having a rest mass roughly 270 times that of the electron. It exists in neutral, positive, and negative charged states.

PIOR :

Programmed Input/Output Retrieval. PIOR is standard hardware for receiving data from links around the accelerator, including PDP-11 to console communication, Tevatron links, and QXR.

PIOX :

Programmed Input/Output Transmission. PIOX is standard hardware for transmitting data to many of the links in the accelerator.

Pit :

A large temperature and humidity controlled room containing the Haefely high-voltage transformers, voltage multiplier, preaccelerator dome, column, and motor-generator for the preaccelerator.

Pixel :

A Picture element. A point on a TV or Lexidata screen; the smallest unit used to construct characters or images.

Plasma :

A high-temperature mixture of ionized atoms and electrons.

Plateau (to Plateau Counters) :

The process of optimizing the efficiency of particle counters versus acceptable levels of noise, multiple counts, or voltage. Generally the efficiency of a counter is plotted versus applied voltage and the rapidly rising curve flattens out (plateaus) at some value where noise, etc. is still acceptable. Generally one will try to run counters well into the plateau region if other considerations permit because their efficiency is less subject to change from small changes in the applied voltage.

PLD :

Program LoaDer. A managing program on the console computers which works in conjunction with CPLD (Central Program Loader) to download applications programs from the VAX. It also monitors the cache of the 50 most used applications programs on that console and verifies that the most recent version of each program is being used.

Plessey box :

Plessey is the name of the company which makes the Unibus extender box, or more explicitly the Plessey Peripheral Systems PM-1150/5 extender unit. Same as the PEX box (see above).

Polarity Check :

Procedure used to insure a magnet will have the desired polarity when powered. Checking the polarity of magnets by measuring the magnetic field with a Hall Probe is one way to accomplish this. In the Tevatron it can mean to check which of the superconducting leads on the end of a magnet are upper or lower bus.

Polarization :

The preferential alignment of the spin of a particle along a particular axis in space defined e.g. by the electric or magnetic field direction, or the momentum vector of the particle itself.

Port Selector :

A communications multiplexor for connecting terminals to various computer systems such as the AD VAXcluster and FNAL VAX Cluster.

Positron :

The antiparticle of the electron. It has the same mass as the electron but opposite (positive) electrical charge.

Post Coupler :

A copper stem with a tab on the end that is used to control the relative field levels in two adjacent cells in a linac RF cavity.

Power Glitch :

A power glitch is an interruption of electrical power lasting only a fraction of a second.

Power On Access :

Entry into an enclosure in which devices are energized. Because of the lack of electrical insulation in some of these areas electrical hazards may exist.

Power Supply Program :

A series of computerized commands which tell a power supply what waveform to produce throughout a given cycle.

PPE :

Personal Protective Equipment

Preacc :

See preaccelerator.

Preaccelerator :

Generally refers to all the hardware associated with the production of 750 keV ions, including the source itself and the Haefely power supply. The general layout is of the Cockcroft-Walton type.

Predet Timer Board :

A hardware box which delays a timing event by a predetermined amount. Predets are set manually by switches on the front of the box. They can be thought of as hardwired alternatives to the CAMAC 177 modules. They are used in the Pre- Acc for triggering devices in the domes and in the Linac, as well as in the MCR as delays for scope triggers.

Prepulse :

Event on the booster clock that commands the 200 MeV, booster, and 8 GeV pulsed devices to fire in preparation for a beam pulse. Linac beam is not allowed on prepulses.

Pressure :

The force exerted per unit area. The units are pounds per square inch absolute (psia), pounds per sq inch differential (psid), or pounds per sq inch gage (psig). see Atmosphere.

Primary Applications (PA) :

Applications programs which allow interaction with a console user. All of the console resources: screens, touch panels, etc. are allocated to the PA while it is in use.

Primary Collimator :

The first collimator after the beryllium target used to produce neutrons for NTF. The primary collimator is made of steel and is of fixed geometry.

Primary Critical Device :

The principle device that determines whether or not beam will enter a certain enclosure. Critical devices are controlled by the safety system, as well as through the control system. The primary critical device for the linac is the beam stop in the 750 keV line. The secondary critical device for the linac is the pulse shifter.

Primary Microprocessor :

Choke point of the linac control system that controls messages on the serial data link, and interfaces with the host computers via the Ethernet link.

Primary Station :

See Linac Primary.

Printed Circuit Board :

An insulating surface containing a circuit made by depositing conductive materials in continuous paths from terminal to terminal. Complex electronic circuits are made by soldering components to these terminals.

Printronix :

One of the printers in the computer room accessible through the Development VAX. Also known as the LXY22, it is a dot-matrix line printer that operates between 320 and 600 lines per minute depending on the complexity of the printout (i.e., all upper-case, mixed upper-lower case, or double-height characters). We also have the optional PLXY graphics software package. The DI- 3000 graphics package can drive the Printronix in graphics mode.

Production Angle :

The angle between a targeted primary beam and a secondary beam is called the production angle.

Prom Module :

Logic module in the preacc control room that looks at the various beam enable inputs and decides which, if any, will produce a beam pulse. The prom module also selects the chop width to be sent to the choppers.

Prompt Muon :

(see Direct Muon)

Property Index (PI) :

A secondary address pointer in the VAX database which associates the device index of a parameter with a property. Properties include such things as names, text, alarm limits, basic control, etc.

Proportional Wire Chamber (PWC) :

A PWC is made up of fine parallel wires. The wires serving as anodes are located parallel to a cathode of foil or wires. The voltage and pressure of the gas in the chamber can be adjusted so that ions, liberated by passage of a charged particle, are accelerated to sufficient velocity to produce fresh ionization by collision, a phenomena known as gas multiplication. The output voltage pulse generated when the electron avalanche reaches the anode is then proportional to the initial ionization.

Proton :

An elementary particle that is the positive unit charged constituent of ordinary matter. Its mass is 938 mev and has a spin of 1/2. Protons are one of the particles constituting all nuclei. It is currently believed that protons do not decay although experiments are going on to prove that they do have a half life of approximately 1030 years. It is believed that most of the matter in the universe is in the form of protons. At Fermilab protons and antiprotons are the particles accelerated.

Pull down window :

A boxed set of options available upon interrupting. Used especially for copy options on a parameter page.

Pulse Interlock Module :

Linac component in the modulator pulse- forming circuitry that will inhibit the modulator pulse if conditions warrant.

Pulse Repeater :

Module immediately after the pulse shifter in the preacc control room that sends the pulse to the chopper predets, the H- and I- clock generators, two of the A/D units for secondary #G, and secondary #G itself.

Pulse Shifter :

Module in the preacc control room that will delay the reset pulse to the sources by 1 msec if no beam is desired in the linac. Controlled by the prom module, safety system status, and vacuum valve status.

Pulse Shifter Status Module :

Module in the MCR that shows the Linac pulse shifter status and can reset a pulse over count if one occurs.

Pulse Skip Detector :

Module in the preacc control room that senses when one or more of the 1-gap phase reversals from the clock module is missing (should occur at 15 Hz) and sends a message to secondary #G so that it can post an alarm.

Pulse Train :

A sequence of electronic pulses generated by a device. The frequency is interpreted as a numerical value. Examples include the intensities for the various beam lines appearing on Channel 13, and the hardwired loss monitors for the Switchyard.

Pulse Train :

A stream of electrical pulses representing a single quantity. In the Laboratory it usually represents analog information from a device such as a SEM or loss monitor which is converted into a stream of pulses which are counted by scalers. This information is generated on the CAMAC controls system by an 040 or 049 CAMAC module and is available via a CAMAC crate.

Pulsed Devices :

A pulsed device as it relates to accelerator beam line components is one that is triggered to come on at a preset time or event. The pulsed device is powered from a large power reservoir such as a capacitor bank. When the trigger is received the power reservoir dumps its energy into the device. The energy in the device then decays off naturally. The advantage of a pulsed device is that a high level of power can be put through a small device in a short period of time. Some typical pulsed devices are kickers, magnetic septa, and electrostatic deflectors. The pulsed trims in Switchyard for steering fast beam around the electrostatic splitting septa are also pulsed devices.

PV :

Pneumatically operated Valve

PV :

Pulsed Vertical trim. A small vertical trim magnet which is pulsed to steer fast spill around splitting septa.

PVT :

PVT stands for Pressure, Volume, and Temperature, the fundamental variables of the state of a pure fluid at equilibrium. Any two of the three variables may be specified. The third is then a unique value for a given fluid except where two or more phases coexist in which case the pressure is a unique function of the temperature but the volumes of the phases differ.

-Q-

QA :

Quality Assurance

QBS :

Quench Bypass Switch. System which bypasses the ring current around a quenched magnet cell. It is controlled by the QPM.

QPM :

Quench Protection Monitor. The microprocessor system which monitors superconducting magnets for a quench condition or refrigerator problems that could induce a quench. In the event of a quench it takes action to protect the magnet system by firing the HFUs, pulling the Dump and Bypass loops, dropping the TECAR ramp, etc. It is sometimes called Quench Protection Mess.

QPM Link :

A 50 ohm RG-8U coaxial cable located in the Main Ring tunnel which carries information essential to the quench protection system. TECAR, the Tevatron power supply controller, refreshes the information every 720 Hz. The link carries information about the current in the Tevatron bus which the QPM's decode locally in order to evaluate conditions inside the magnets.

Quad Enclosures :

Three underground enclosures in the Proton- West beam line containing a system of magnets and collimators designed to reduce the halo which accompanies the primary proton beam.

Quadrupole :

A magnet consisting of four poles ("quadrupole"), used for focusing beams of particles.

Quadrupole :

A magnet having four poles which serves to focus the proton beam in one plane. A focussing quadrupole serves to focus in the horizontal plane while a defocussing one focuses in the vertical plane.

Quadrupole Steering :

The bending of a particle beam by a quadrupole caused by the beam passing through it off-axis.

Quadrupole Triplet :

A series of three quadrupoles of alternating polarity that produce a net focusing of the beam in both planes. Typically the two outer elements of a triplet are wired in series.

Quark :

A fractionally charged particle hypothesized by Gell- Mann and Zweig to explain hadron structure. In a simple quark model the proton, for example, is composed of three quarks with charges 2/3, -1/3, and -1/3 of the electronic charge. The quark theory has provided to be a very successful mathematical model. All quarks have been detected at accelerators around the world except for the Top quark. Intensive search is underway at Fermilab for the Top quark particle on which the standard model of particle physics depends. The experimental verification of the existence of the Top quark and an analysis of its properties would provide important unifications in particle physics and insights into the structure of matter.

Quench :

The change of state in a material from superconducting to nonsuperconducting ('normal'). In the Tevatron this process is potentially damaging to the magnets. When the superconductor material quenches the material passes from the superconducting state to a normal resistive state. The Niobium alloy superconductor in the Tevatron that is now a normal resistive conductor heats up very quickly due to the extremly high currents passing through the magnets (4400 amps). Typically only one small piece of the superconductor is the first to quench and the heating of this one spot causes it to expand in volume quickly in relation to the surrounding colder material. Thermal stress induced by this sudden expansion can cause the magnet to break. For this reason very elaborate Quench Protection Monitor (QPM) systems electronically monitor the superconducting state of the Tev magnets. If a quench is detected beam is aborted and Heater Firing Units (HFU) are discharged to heat the entire magnet up evenly. The magnet must then be cooled down to superconducting temperatures again before current can be passed through.

QXR :

Quadrupole eXtraction Regulator. The system which controls the rate of extraction from the Tevatron. It is composed of a microprocessor system which controls special air core quadrupoles in the Tevatron.

QXR Link :

The link which transmits the programmed waveform to the Quad Extraction Regulator crates. It originates at the QXR microprocessor in the MAC room.

-R-

RA60 disk drive :

A rack mountable, removable-media disk providing 205 Mbytes of storage for the VAXCluster.

RA81 disk drive :

A rack mountable, fixed-media disk which uses Winchester technology to provide 456 Mbytes of storage for the VAXCluster.

Rack In/Out :

Connecting/Disconnecting power to a power supply (or its transformer) via its manual disconnect switch. For the operations group the term also means to go to the Master Substation to connect/disconnect and energize the Main Ring and Tevatron feeders.

RAD :

Measurement of radiation dosage. It is the amount of radiation required to deposit 100 ergs of energy per gram of any substance.

Radial position :

Position of a particle or particles in the horizontal plane relative to the center of the beam pipe.

Radian :

A measure of angle. 360 degrees = 2p radians. The radian measure of an angle is given geometrically by the ratio arc length/radius of the arc of a circle with the angle defined at its center and subtending the arc.

Radiation :

Heat transfer by emission. Unaffected by insulating vacuum. Varies as DT4.

Radiation :

Emitted energy in the form of electromagnetic waves (photons) or ionizing particles (electrons, alpha particles or nuclei).

Radiation Baffles :

An inactive set of shields designed to reduce the effects of cryogenic radiation.

Radiation Length :

A radiation length is defined as that thickness of material required to reduce the mean energy of an electron beam by a factor of e h2.718.

Radiation Shield :

An active (cooled) shield designed to intercept cryogenic radiation. Often cooled by LN2.

Radio Frequency :

In comparison with other electromagnetic waves or oscillations, radiofrequencies are low frequencies (H103 - 1010). The frequency of the accelerating electric field falls in the range of radio frequencies and RF in an accelerator refers to this accelerating field.

Ramp :

Varying the output current/voltage of a device as a function of time.

Ramp :

To excite a magnet with a time dependent excitation current. A time varying excitation current for a magnet used either to track changing beam energy or to reduce average power dissipation by reducing the excitation when the magnetic field is not required. At Fermilab, the Main Ring and Tevatron bending magnetic field varies with the energy of the accelerating protons in order to confine them within the Main Ring beam pipe. The ramp waveforms of Main Ring and the Tevatron are displayed on closed circuit TV throughout Fermilab along with the beam intensity.

Ramp Enable :

A permit sent to the NTF 58 deg magnet power supply telling it that it may ramp. The ramp enable comes from the NTF interlock module.

Range :

A charged particle traversing a medium loses energy in collisions with atomic electrons. The range is the distance the charged particle travels before coming to rest in the medium. A measurement of the range may be used to give the energy of the incident particle.

RCRA :

Resource Conservation and Recovery Act

RD :

Research Division

Reboot :

To restart a computer by using the "bootstrap loader" to retrieve the correct program from a peripheral device, e.g., disk. See Boot.

Red-Dot Board :

One type of binary I/O board found in a linac secondary connected to OPTO22 devices to provide optical input and output to the secondary.

Reference Source :

Part of the monitor/control module in the PreAcc Haefely control system that produces a command voltage for the power supply in response to computer commands or local input.

Refrigeration :

The extraction of heat at lower than ambient temperature.

Regulator (A0) :

Transistor power supply used to provide a smoother output to the Main Ring quadrupole bus at injection than is possible with standard SCR power supplies.

Regulator/Oscillator Module :

Module in the Pre acc Haefely control system that receives the digitized command and monitor voltages from the monitor/control module and uses them to generate a drive signal for the power amplifier. The regulator/oscillator also receives an input that represents the high-voltage transformer output and uses it for regulation.

Relief Valve :

There are two uses. (1) Pressure, set to MWP + 10% and (2) Thermal, set to relieve at a pressure conveniently above the system working pressure but below MWP to provide for cryogen expansion. The Frig building relief valves on the roof tops are an example of the first usage. The Kautzky valves are an example of the second.

REM :

Roentgen Equivalent for Man. A measurement of radiation dosage. It is the amount of radiation required to deposit 1 Joule of energy per kilogram (i.e., 100 ergs/gm) of body tissue. REM = (Quality Factor)x( RAD) Q.F. depends upon substance.

Remnant field :

(also spelled remanent). The field remaining in the magnet after its excitation current has been removed. It is particularly important in ring magnets at injection, where the total magnetic field is made of the powered field plus the remnant field; this causes field errors which must be compensated for during the injection process.

Repeater :

A module which receives information from a link and retransmitts it to points further downstream.

Resistive wall effect :

As beam intensity is increased in a synchrotron, image currents flowing in the walls are increased, attracting the beam at high betatron oscillation points thus enhancing the betatron oscillations toward an unstable state.

Resolution :

Roughly the minimum separation of two objects or events for which they appear distinct and separate.

Resonance :

Usually used to mean "betatron resonance" when talking about an accelerator; it occurs when some perturbing force in the accelerator distorts the orbit in a periodic way, causing the betatron oscillations to grow larger and larger, until beam is lost or perhaps extracted.

Resonance :

A phenomenon of AC circuits where they exhibit relatively large currents at certain frequencies.

Resonant Circuit :

see Tuned Circuit

RETDAT :

RETurns DATa. A program present on all front-ends which receives request lists for data from consoles and organizes those lists to be sent out to the appropriate CAMAC crates in the field.

Retraction spring :

A small piece of wire used to keep broken septum wires from shorting the cathode to ground.

Reverse Power :

The RF power from an amplifier that is reflected back by the load. The power not reflected back is the forward power. The sum of the two represent the total power of the amplifier. In RF station tuning, the reverse power between stages is always tuned for a minimum.

RF :

RadioFrequency. It is the type of electromagnetic energy used in acceleration systems. See Radiofrequency.

RF Bucket :

That area in RF phase where particles oscillate about the synchronous phase angle. Particles in an RF bucket will normally remain in the bucket. Particles outside the bucket will not be accelerated.

RF Cavity :

An electrically-resonant standing-wave cavity designed to impart energy to particles as they pass through a gap or number of gaps in the cavity by virtue of the electric field gradient across the gap(s).

RF Defocussing :

Phenomenon caused by the curved fields in the gap between drift tubes and the changing electric field strength that results in radial defocussing of the beam as it is accelerated between drift tubes.

RF EAST MAC :

A MAC-16 minicomputer which handles digital control of Booster stations 1-8 in the East Gallery. Digital control means such things as turning stations or anode supplies on and off, etc.

RF Phase Adjust Module :

Linac module in the low-level RF system that adjusts the phase of the input RF from the master oscillator under the direction of the local secondary microcomputer. This adjustment controls the intertank phase.

RF WEST MAC :

A MAC-16 minicomputer which handles digital control of Booster stations 9-18 in the West Gallery. Digital control means such things as turning stations or anode supplies on and off, etc.

RFGE :

RF Gap Envelope. RF abbreviation. This is the RF voltage that is present on the gaps of the cavity beam tube that accelerate the beam. There are two gap monitors on each cavity and are referred to as upstream and downstream. They both read the same gap voltage and should present readings that are within 2% accuracy.

Rigging :

The heavy material or instrumentation of an experiment must be moved into or rigged into a certain location. This usually requires a crane and a special crew referred to as riggers.

Right Bends :

A set of bending magnets that initially direct the beam toward the Proton Area. Also known as the MH-300's.

Ripple :

Oscillation about the desired output value of a power supply. May sometimes be loosely used to indicate any type of noisy output.

Ripple :

An a.c. component or a periodic fluctuation of a direct current or voltage. Ripple is generally the result of inadequate filtering of the voltage produced by an a.c. source.

RL02 disk drive :

The disk drive common to all PDP-11 computers. The console computers have two disks, one of which carries the cache memory while the other one carries the management programs. The front-ends have only one disk.

RM80 disk drive :

A fixed media 124 Mbyte (formatted) disk drive used on the Development VAX.

Roentgen :

Measurement of radiation dosage caused by X-rays and gamma radiation. It is the amount of radiation required to deposit 97 ergs of energy per gram of air.

Roughing :

The first stage of vacuum pumping. It generally ranges from atmospheric pressure down to a few microns (one micron is 0.001 mm of mercury).

Roughing Pump :

A rotating-vane pump used in the initial stage of vacuum pumpdown, good down to about 10-3 torr.

RSO :

Radiation Safety Officer

RSS :

Radiation Safety System. Logic system for a particular enclosure that controls the primary and secondary critical devices for that area. Inputs to the RSS include the status of the gates leading to the enclosure, the emergency switches in the enclosure, and whether or not the enclosure has been secured.

-S-

S1, S2 :

Pulsed magnetic septums located at the start and end of the 200 MeV line.

SA0040 :

The secondary applications program which operates the AEOLUS alarm screen.

Safety lead :

Connection from the Tevatron main magnet bus to the QBS's. They are found at each spool piece downstream of a defocussing quadrupole.

Sample and hold :

This is a circuit, used throughout the accelerator, which upon command records the value (analog or digital) of a device in a buffer and holds this value until it receives a command to reset its buffer.

Sample time :

The time, unique to each accelerator subsystem, when data is loaded into buffers for use by the MCR or sampled by the front-end computers.

SAP :

Self Assessment Program

Saturation (loss monitor) :

A loss monitor readback which has exceeded its maximum of 10.23 volts. At this point further losses do not result in a larger readback.

Saturation (of a magnet or of iron) :

A magnet is said to be showing saturation when its field no longer rises linearly with the excitation current. The term properly applies to the steel of the magnetic core in which the permeability falls from a large value at low excitation to a value approaching that of vacuum at high excitation when all the magnetic domains are aligned with the field.

Save file :

This term generally refers to a filesharing file containing some type of data or information related to accelerator operation. These files are generally temporary. The purpose of these files is to record current operating conditions so that they may be hopefully duplicated at a later date.

Scaler :

An instrument used for counting electrical pulses and displaying the result in digitized form. Scalers my be used to display beam intensities, bubble-chamber-picture counts, etc. In NTF a Scaler is a hardwired device in the NTF control room that acts to terminate patient exposure in case the beamline mP fails to do so at the proper point. The scaler contains counters and timers not associated with the control system and inputs directly to the NTF interlock module.

Scaling :

The conversion of MADC voltages into engineering units which humans can understand. Scaling factors for the devices in the ACNET system are kept in the database of the VAX.

Schottky (pickup, signal, bands) :

Schottky pickups are beam detectors, like BPM's, which are tuned to be sensitive to the revolution frequency of the circulating beam as well as the revolution frequency harmonics. If the signal from a Schottky pickup is looked at via a spectrum analyzer, the momentum spread and tunes can be measured by looking at the width of the Schottky bands and by looking at the amplitude of the revolution harmonic sidebands.

SCR :

Silicon Controlled Rectifier. Also called a thyristor. A semiconductor rectifier whose forward anode-cathode current is controlled by a signal applied to a third electrode. The SCR will latch into a forward bias. Widely used in power supplies throughout the laboratory.

SCR (Save/Compare/Restore) :

A program which reads the current value of D/A settings, A/D readbacks, nominal values and alarm states and loads this information into a semipermanent buffer residing in the VAX. The program, currently found on page D1, can also read the saved values and display them on the console TV, load them back into the devices, or compare differences between two save files.

Screen Image Editor (SIE) :

A primary applications program, currently found on D10, which allows editing of the TV screen and touch panel on behalf of another applications program.

SDA :

Sequenced Data Acquisition. Used to gather data about a shot from start of shot set up to end of low beta squeeze. Runs on the VAX and saves information to a file to be reviewed later.

SDLC :

Synchronous Data Link Control. A data link communication protocol developed by IBM and used to control a serial data link (or SDLC link).

SDLC fiber optic link :

Serial Data Link Controller. The Linac secondaries and Tevatron QPMs use an IBM serial link protocol which transmits and receives data along an external fiber-optic link.

Search and secure :

The method of searching an accelerator enclosure in a logical fashion and resetting safety system interlocks to ensure that no personnel are in the enclosure before turning on power supplies and sending beam through that enclosure.

Secondary Applications (SA) :

An operating program for which console control has been relinquished. Typically an SA continues to update a Lexidata or storage scope with fresh data, although the console is also being used for other purposes.

Secondary Particles :

Those particles that are produced by hitting a target with the primary proton beam from the accelerator.

Secondary Station :

Same as a Linac secondary. It provides local control and monitoring for a given Linac station.

Segmented Wire Ion Chamber (SWIC) :

A SWIC resembles a wire spark chamber consisting of three parallel wire planes. A plane of horizontal signal wires, a high voltage plane, and a plane of vertical signal wires. The wires are connected to an integrating and scanning circuit capable of holding, scanning, and dumping the ionization current collected by the wire when the proton beam passes through the device. Its purpose is to give a profile of the beam.

SEM (grid) :

The diagnostic devices used to measure beam position in the Antiproton source transport lines. SEM's are close relatives of multiwires as found in the 750 keV, 200 MeV, and 8 GeV lines as well as Switchyard SWIC's. The grids crossed x,y 10 micron titanium strips with either 1.5 or 3.0 mm grid spacing. The electronics includes modified up-based SWIC scanners as used in the fixed target experimental areas.

SEND button :

A button at the lower left-hand corner of the keypad at a console terminal. It provides interrupt capability for the AEOLUS screen. Nowadays this button is blue and is labeled RESET.

Sense Switch :

This is an external device (generally a set of switches) which is capable of modifying program flow or control by the orientation of the switches. For ACNET consoles the sense switches are areas defined on the touch panel screen which when activated modify the program function or display in some way. A typical use of the switches at a console terminal might be to modify the format (A/D, D/A, etc.) of the data displayed on the TV screen, or modify the characteristics of the keypad interrupts.

Separatrix :

In a phase space diagram, the boundary which divides the stable beam region from the unstable beam region.

Septum :

A device for deflecting beam from its normal path. Some septa (plural of septum) use a magnetic field and have a thick, curved copper plate for a current carrier; others are electrostatic and use a thin plane of wires to set up the electric field.

Septum :

A magnetic or electrostatic device used to deflect charged particles along one of two paths. Typically, a solid metal sheet or plane of wires separates a region with and electric or magnetic field from a region of no field. Beam entering the first region is deflected while beam entering the second region is not.

Septum, electrostatic :

A device which splits the proton beam into two beams. It consists of a chamber bisected by a row of fine wires. On one or both sides of the wires there exists an electrostatic field(s) which serves to separate the two beams.

Serial :

Data transmitted one bit at a time. Many of the links at Fermilab are serial links. Normally this data must be reconstructed into a parallel format before it can be used by a computer.

Serial Data Link :

Also SDLC link. A fiber-optic data link that connects the primary and secondary microcomputers in the linac control system. Data is transmitted on a 1 MHz Manchester-encoded clock under SDLC protocol.

Series SCR :

The SCR which bypasses Tevatron current around the dump resistor except under ramp dump conditions.

Set Point :

In the context of feedback systems it is the nominal value toward which the system strives. In a controls context it is the D/A value of any parameter when an applications program is entered.

SETDAT :

A program present on all of the front-ends which organizes lists of D/A setting values before they are sent to the hardware.

Sextupole :

A magnet with six pole faces, used for correcting magnetic field errors.

Shift Plot :

A plot done at the end of each shift and posted in the crew chiefs log. The plot is an indication of overall productivity of the accelerator. For fixed target mode Tev accelerated intensity is plotted over the duration of the shift. For collider mode luminosity and the pbar stack are plotted. Any downtime is also indicated on the shift plot.

Shift Save :

A methodical saving of pertinent accelerator parameters, rf curves and ramped devices. The save is done according to a checklist once every 24 hours during accelerator operation. In the event of a failure of the accelerator, the last running conditions can be recalled from the shift save to restore the accelerator to running condition.

Short Sample Limit :

This is the figure of merit for a superconducting magnet. It is the highest field possible just before the critical magnetic field of the superconducting wire is exceeded. 1

Shot :

see Pbar Shot.

Shunt Impedance :

Technically, an impedance in parallel with an electrical circuit. In this application, the ratio of the square of the electric field strength on the axis of an RF cavity to the power dissipated per meter of length.

Shunt SCR :

The SCR which bypasses a Tevatron power supply from the circuit in the event of a ramp dump or fast bypass.

Shuttered Kicker :

Kicker magnets are used to put the injected antiprotons from the Debuncher onto the Accumulator injection orbit and to kick out bunches of p-'s from the Accumulator towards the Main Ring. Since there is almost always circulating beam in the Accumulator during stacking or unstacking operations, a magnetic shield, or shutter, is placed between the circulating beam and the beam to be kicked, thereby shielding the circulating particles from the effects of the kickers. These shutters are physically moved out of the beam once the kicker pulse is completed. The use of these kickers would be impossible were it not for the the use of high dispersion regions, which permit radial separation of the circulating beam as a function of momentum. Both the injection and extraction kickers are located in straight section 20.

Sibling :

A device which is logically or sequentially related to other devices; for example, two consecutive horizontal correction dipoles.

SIDO :

SIlicon DOrk. Generaly used as a friendly derision for any person that is extremly knowledgable about computers and computer systems. SIDOs consider it a point of honor to be known by such a title. Such knowledge extends way beyond that gained from everyday work usage or study. There are many computer professionals that work with computers every day that do not qualify for SIDO status. The level of computer edification needed to qualify someone as a SIDO can only be had by those who posses a passionate intrest that borders on the fanatical in anything to do with computers. SIDOs appear as true wizards able to do things that others thought difficult or impossible to accomplish. SIDOs willingly and often spend all hours of the night exploring new systems and devices, communicating among themselves in a language totally foreign to anyone who is not a SIDO.

Silicon Controlled Rectifier :

A rectifier having the ability to begin conducting at an arbitrary phase of an AC current cycle. A normal rectifier conducts for 180o of phase (Zener diodes excepted). An SCR conducts only after it has received a firing pulse, then continues to conduct until the polarity changes, so one can selectively chose to conduct on any phase F, such that 0 Skew correction element :

An n-pole correction element which is rotated by an angle of 180/n degrees. (Note that in this scheme, a vertical dipole is actually a skew horizontal dipole.)

Skew dipole :

Dipole magnet rotated from the horizontal plane by some fraction of 90 degrees so that it bends the beam both horizontally and vertically.

Slow spill :

The resonant extraction of beam from the Tevatron over a period of at least several seconds.

Slow Spill :

Ejection of the circulating beam from a circular accelerator over many turns (up to tens of thousands of turns or times of the order of a second). In modern synchrotrons slow spill is achieved by slowly adjusting the focusing field toward a betatron resonance so that the oscillations are stable for a steadily decreasing range of amplitudes until at the end of the spill no oscillation is stable. The unstable oscillations are phased to carry the beam particles into the extraction channel. 1

Smart module :

A relative term used to designate a module which can do some amount of internal data processing or error checking. All of the microprocessors, such as the HOG's, BPM's, QPM's, and Refrigerators, can do this, as well as many smaller units such as 080, 160, and 165 cards, etc.

Smeds Module :

Module in the MCR built by Jim Smedinghoff (Smeds) that allows computer enabling of 15 Hz beam for use by the linac steering program (L36).

Snapshot :

In general terms, this refers to data taken at some specific time over a small time interval. The data obtained may or may not be representative of events over a longer time interval. A specific use is the Beam Position Monitor (BPM) data averaged over a number of turns and stored in a circular buffer. Another important use is for diagnosis of problems; for example, when the ramp trips a snapshot of the voltage-to-ground is taken and may be placed in a circular buffer to be analyzed at a later time.

Software :

The programs, routines, etc. for use in a digital computer, as distinguished from the physical components (hardware) of the computer.

Software Documentation Memo (SDM or SODOM) :

A publication distributed by the Controls group which is intended to clarify operational aspects of software usage. This is primarily used for descriptions of major software utilities, control system theory, and not for application program documentation.

Space Charge :

A radially defocussing force caused by electrostatic repulsion and magnetic fields generated by the moving protons within an accelerator.

Space Charge Forces :

Divergent forces on a charged particle beam caused by nonzero net charge density, i.e.: mutual repulsion.

Spark Chamber :

An instrument for detecting and measuring the paths of elementary particles in an experiment. It is analogous to the cloud chamber and bubble chamber. It consists of numerous electrically charged metal plates mounted in a parallel array the spaces between the plates being filled with an inert gas. Any interaction causes sparks to jump between the plates.

Spark Chamber :

An instrument for recording the position of ionizing particles. A visible electrical discharge (spark) occurs at a point where a charged particle traverses a small gap between oppositely charged plates or wires. Spark chamber data may be collected photographically (optical spark chamber) or electrically (wire spark chamber). Many charged gaps are sometimes used. The charged particle trajectory may be traced by the sequence of sparks created through such a multi-gap system.

Spark Gap :

Electrodes found on the Haefely voltage multiplier and the accelerating column that will arc in the event of a voltage imbalance and thus prevent an arc from occurring in expensive/inaccessible components.

Specific Heat :

Heat capacity per unit mass per unit temperature change (J/gRK)

           
                               Cp = DH/DT, Cv = DU/DT.

Spectrometer :

A device for producing a spectrum. The 40R bending magnet in the Linac momentum analysis line comprises a magnetic spectrometer. Particles with different momenta will follow different paths through the magnet and will appear in different positions at the scanning wire.

Spectrometer :

A system for determining the momentum of a particle, usually by measuring its curvature in a magnetic field. A spectrometer might consist of a string of bending magnets as in the single-arm spectrometer in the M6 line of the Meson Area, or it might consist of a single large magnet such as the Chicago Cyclotron Magnet in the Muon Lab.

Spike :

An undesired intense portion of the spill.

Spill :

Beam extracted from the Tevatron. Using resonant extraction, the beam "spills" out of the machine a little at a time.

Spill :

Spill is the time structure of the extraction beam. This is of particular interest to those experiments which are often limited by problems of "accidental coincidences" and equipment dead time. 1

Spill Duty Factor :

The spill duty factor is a quantitative measure of the quality of the beam being extracted from the accelerator. The spill duty factor is given the range 0% - 100% and measures 1) The amount of time extracted beam is on divided by the maximum time it could be on and 2) The uniformity of the instantaneous intensities over the length of the flattop.

Spill structure :

The regularity or lack thereof of spill intensity over time.

Split :

The split of split ratio is the amount of beam going to a particular external experimental area divided by the amount of extracted beam, usually given as a percentage. It also refers to the septa, and bump magnets that control this ratio, i.e., a splitting station.

Splitting station :

Place where a single incoming proton beam is split into two or more beams. The primary elements of a splitting station are septa and lambertsons.

Spool piece :

The device that contains the Tevatron correction element coils.

Spot size :

The transverse size of the proton beam at a given point. It is usually referred to at a target.

SSDN :

Sub-System Device Number. Each database entry in a given subsystem (e.g. Linac, Tevatron, etc.) has a unique number assigned to it. This number is used by the front-ends and describes characteristics such as module type, location, etc. The format of these numbers is different between front-ends and different for each property of a device.

SSO :

Senior Safety Officer

Stack :

Antiprotons are stored in the pbar Accumulator storage ring. Antiprotons are produced by bombarding the antiproton target with protons, sweeping the antiprotons into the circulating Accumulator antiproton beam, and stochasticaly cooling them. This process is called stacking. The antiprotons collected in this manner are collectively called the stack. The amount of antiprotons stored in the stack are measured in milliamps.

Stack tail :

The least dense region of the p- beam in the Accumulator. Beam is deposited onto the stack tail by ARF1 and the stochastic cooling systems, specifically the Stack tail Dp system, move the p-'s from the tail towards the core. The particle density of the stack increases in an approximately exponential fashion from the stack tail to the core.

Stacking (RF & momentum) :

The means by which successive pulses of antiprotons are combined into one beam in the Accumulator. This is accomplished by first moving an injected pulse of p-'s from the injection orbit to the edge of the stack tail by means of RF deceleration (ARF1). The beam is then pushed towards the core by the stack tail momentum cooling system.

Stage :

To write (or cache) an applications program onto the console disk from the VAX, where it may be easily retrieved.

Stainless Steel :

18% NiCr steel with low conductivity, nonmagnetic, and good cryogenic material properties. Typical cryogenic types are 304, 304L, and 316, all low carbon.

Status Display Unit :

A set of LED's that is interfaced to several Unibus cards in the PEX box which indicates the activity of the processor or external interrupts. This unit may be found interfaced to all PDP-11's.

Stem-Box Cover :

A cover over the tops of the Linac drift-tube stems that protrude from the top of a linac RF cavity. The Stem- box cover may be evacuated to prevent vacuum leaks around the stems.

Stepping motor :

A motor which rotates a small specific amount in response to an encoded bit of information. It allows beam-line elements to be moved precise distances.

Stochastic, Stochastic Cooling :

A random process. Stochastic cooling works through a series of beam pickups, electronics, trunk lines and kicker electrodes. Consider the case of an individual p-. The particle passes through a pickup and some position is detected. Depending on the location of the pickup in the lattice, the position can be translated into a transverse or momentum error. The signal from the pickup is massaged electronically and transported across the ring to more electronics which serve to insure that the error signal derived at the pickup arrives at the kicker just as the p- arrives at the kicker (at the correct amplitude and phase to correct the error). Real time feedback. The actual process is slightly more complicated, both in practice and due to the fact that more than one particle comprises the beam.

Stochastic cooling :

A technique used in the antiproton source to reduce the beam size to make room in the Accumulator for the number of antiprotons required for collisions with high luminosities. Several hours are required to collect the needed antiprotons and increase the density of the beam in order to achieve the desired luminosity.

Stopband :

Vertical and horizontal tune values at which field errors can cause beam blow up in an accelerator. These stop bands have a definite width, so that the beam reaches resonance as the offending tune value is approached. Tevatron extraction is produced by widening the half-integer stop band.

Storage Ring :

A storage ring is a ring of magnets having the capability of storing particles from an accelerator for periods of up to many hours. Its purpose is to make possible very high energy collisions by colliding the beam "head on" with an oppositely directed beam.

Storage Scope :

Any oscilloscope or display which retains a trace for an indefinite length of time. There are several portable scopes available for diagnostics as well as at least one at most ACNET consoles in the MCR. Sometimes the term refers specifically to the Tektronix 613 storage scope at each ACNET console.

Store :

To inject circulating beam into an accelerator and keep it there for long periods of time. In the Tevatron this means to inject protons and pbar bunches, cog the bunches to their proper collision points, ramp the Tev to 900 geV, turn on the low beta quadrupoles to bring the injected beam to low beta, and the collider detector experiments are taking data. In the antiproton source, it means that an antiproton stack is established.

STP :

Standard Temperature and Pressure. 0ºC and 1 atmosphere.

Straggling :

Because of the statistical nature of the collisions of charged particles with atomic electrons, the range of the charged particles is not unique, but is actually a mean value R. Fluctuations about R is called straggling.

Strangeness :

A property (quantum number) of elementary particles found useful to classify hyperons into families. Strangeness is conserved in reactions involving the strong interaction. The selection rules resulting from strangeness conservation are very important in explaining why some reactions take place much more slowly than others. In quark models, the strangeness quantum member is carried exclusively by the "strange quark", and hadrons exhibiting nonzero strangeness contain this quark as a constituent.

Streamer Chamber :

A streamer chamber is a wide-gap chamber which records a three-dimensional image of a particle trajectory. An electron avalanche develops along the trail of ions, as in a narrow gap chamber, but because of a short pulse duration, this is arrested at an early stage, so the "track" appears as a row of short streamers extending typically a few millimeters. If the plate electrodes are transparent, the streamers may be viewed along the field and then appear as a series of dots similar to a track in a bubble chamber.

Strong Focusing :

A system for focusing charged particles in which the particles pass alternately through non-uniform electric or magnetic fields having gradients of opposite sign. Strong focusing is employed in the Fermilab Main Ring and Tevatron where quadrupole magnets of alternating signs provide the focusing for the circulating protons.

Subcooled :

The temperature difference between a liquid temperature and the (greater) equilibrium vapor pressure temperature.

Subcooler :

A device to subcool liquid. Accomplished by providing heat exchange to a bath of significantly reduced pressure, equilibrium liquid. Often from the same source.

Sublimation (pump) :

Sputter ion pumps as found in the Main Ring are not sufficient to achieve the ultra high vacuum needed in the Accumulator ring (3X10-10 T), so titanium sublimation pumps are also employed. Sublimation pumps are a form of retainment pump. Retainment pumps operate by capturing gas molecules and retaining them on a surface. The p- source uses Titanium sublimation pumps: a titanium filament is heated so as to cause the titanium to sublime and deposit on the nearby walls as a thin film. This fresh layer of titanium acts as a getter, passing gas molecules react with the Ti and are captured on the surface. Periodically a fresh film must be deposited. This is known as 'sublimating'.

Super Critical :

Pressures, Temperatures, or both above the critical point parameters. Ex, super critical helium.

Super Heat :

The difference between a gas temperature and the lower equilibrium vapor pressure temperature.

Super Heater :

A device specifically designed to provide some degree of super heat. see Vaporizer.

Super Insulation :

Multiple reflective layers of aluminized Mylar to reduce cryogenic radiation heat transfer.

Superbucket :

A superbucket is an R.F. bunch in the extracted beam containing a substantially larger number of particles than the average R.F. bunch. A superbucket arises when the accelerated beam undergoes oscillations which do not effect all bunches equally; typically there is a periodicity of every 3rd or every 7th bunch over a train of thousands or millions of bunches. The term is to some extent a misnomer because "bucket" applies only within the accelerator whereas the effect is most talked about as observed in the experimental area.

Superconducting :

Having no resistive component to electrical impedance.

Superconducting Magnet :

This is a magnet whose coils are made from superconducting material. Superconducting magnets reach much higher magnetic fields than conventional iron/copper magnets at a much lower electrical power cost. They must be cooled to 4 degrees K which is achieved by a continual flow of liquid helium through the magnets.

Superconducting Transition Temperature :

This is the critical temperature below which a substance loses its electrical resistance and thus becomes a superconductor.

Superconducting Wire :

Wire made from materials which become superconducting at low temperatures and are thus able to carry very high currents without losses. Niobium-Titanium is a popular superconducting material that is used in the magnets for the Tevatron at Fermilab.

Superconductivity :

This is a state of matter that many metals and alloys reach at sufficiently low temperatures (i.e. a few oK). This state is characterized by the total absence of electrical resistance thus making possible the conduction of electrical currents without any measurable loss. Superconductivity was discovered by Kammerlingh Onnes in the Netherlands in 1911. He was the first person to liquefy helium and was thus able to reach the extreme cold necessary to observe superconducting effects in mercury.

Superconductor :

A substance which loses all electrical resistance when cooled to or below a critical temperature (typically 5-10 degrees Kelvin).

Supercycle :

The supercycle time is the amount of time required to complete all the different machine cycles that have been defined to operate periodically as a unit. This implies that the supercycle time is periodic and that its length is dependent on the number and duration of different machine cycles defined to occur within its period. It is currently defined from page D69.

Supercycle reset :

The starting point for all of the sequences in a supercycle. It is initiated by TCLK event 00 and takes place automatically when the previous supercycle is complete.

Superperiod :

The large scale repetitive lattice of the Main Ring and Tevatron accelerators which is made up of 14 normal cells, 1 long straight section cell, 1 medium straight, and 1 short straight section cell.

Superposition :

The principle of superposition states that the various wave trains which, in their totality, make up a wave may be considered as mutually independent. The properties of the combined waves can be computed as the sum (phase and amplitude) of the effects of elementary waves, treating the latter as if each were present alone.

SWIC :

Segmented Wire Ionization Chamber. It is a device used to determine beam profiles in the Switchyard and beam lines.

Switchyard :

A system of devices through which the primary proton beam is removed from the Tevatron accelerator and transported to the external targeting stations.

Switchyard front end :

The computer which interfaces with the electronics which control and monitor Switchyard devices. It is presently a DEC PDP-11.

SWIX :

Signal SWitching MatrIX. A software controlled switch for signals to be put on an oscilloscope.

SY :

A common acronym meaning 'Switchyard'.

Synchrocyclotron :

The synchrocyclotron is a frequency modulated cyclotron which is capable of reaching higher energies by compensating for relativistic effects with a variable frequency accelerating voltage.

Synchronous Particle :

A particle that is at the synchronous phase angle with respect to the accelerating RF.

Synchronous Phase Angle :

That RF phase angle at which a particle will receive just enough energy in each cell to reach the next cell just as the RF goes through 360r.

Synchronous Phase Angle :

The phase of the RF field needed to provide the proper accelerating voltage. The synchronous phase angle must be nonzero for acceleration to take place. The synchronous phase angle is zero at injection (provided there is not a phase error) and varied as the bend field in the magnets is increased to provide a positive accelerating voltage.

Synchrotron :

A circular accelerator in which particles are constrained to a roughly constant radius orbit; this requires that the magnetic field increase as the particles' energy increases.

Synchrotron :

A circular machine that accelerates subatomic particles to high energy by the repeated action of electric forces on the particles at each revolution. The particles are made to move in constant circular orbits by magnetic forces that continually increase in magnitude. Fermilab's Booster accelerator, Main Ring, and Tevatron are synchrotrons.

Synchrotron :

A cyclic accelerator where particles are accelerated by radio frequency (RF) fields and constrained in a circular path of constant radius by a ring of electromagnets.

Synchrotron Frequency :

Frequency of longitudinal oscillations of the bunches.

Synchrotron Oscillation :

Synchrotron oscillation is the longitudinal oscillation of particles in an accelerator about an equilibrium of the phase of accelerating voltage at the time the particles are crossing the accelerating gap. The restoring force for the oscillation is provided by a property (phase focusing) of synchronous acceleration that out of time particles receive greater or less acceleration than the in time particles with the correct sense to reduce the time error on the next crossing of the accelerating gap. In synchrotrons like the Fermilab Booster and Main Ring, a particle makes many revolutions around the accelerator in a single synchrotron oscillation period.

Synchrotron Oscillations :

Oscillations about the synchronous phase angle; The oscillation frequency is less than the revolution frequency of the beam.

Synchronous Particle :

The hypothetical particle circulating in phase with the rf voltage about which other particles in the phase-space bucket would oscillate.

Synchrotron Radiation :

Electromagnetic radiation generated by the acceleration of relativistic charged particles in a magnetic field. Synchrotron radiation is the major mechanism of energy loss in electron synchrotron accelerators.

System Ready :

Sum of the second-level interlocks in the NTF interlock module. Two such sums ("A" and "B") are required to be present in order to make up the next level of interlocks.

-T-