R I C H T I P S & H I N T S 1) Monitoring LEDs: There are 4 chains of blue LEDs for monitoring mounted on the top and the bottom of mirrors supporting frame. Each LED is mounted on its own driver card. There is a tech-note about this driver card H-754 (file LED.ps in ~kozh/RICH2001). Each chain requires +12V power supply and POSITIVE trigger pulse (+2V - +5V, 50-100 ns). The last driver card in each chain has terminator to 50 Ohm. Connectors for these LED chains are on RICH downstream flange. They are BNC type. Outlook is shown here (if looking on connectors): EMPTY EMPTY EMPTY 12VA 12VB TRIGA TRIGB EMPTY T1U EMPTY T2U EMPTY EMPTY 12VC 12VD TRIGC TRIGD T3U T1L T2L T3L 12VA-D - +12V power for LED drivers, TRIGA-D - trigger pulses, T1U,T2U,T3U - upper thermocouple inside vessel, T1L,T2L,T3L - lower thermocouple inside vessel (each thermocouple has 3 isolated wires). 2) HV system: HV system consists of 6 Russian made HVPS (2 kV, 200 mA, 220V AC, powered here in Fermilab from 208V 2-phase AC), distribution box based on zener diodes and HV interlock system. There are 8 HVPS available in total (probably they still are Moscow State University property). Zener box has 6 HV inputs (SHV connectors on back side) and outputs for each column (short cables with SHV connectors on front side). All PMTs in one column have the same HV. Column number is marked on the outgoing from zener box cable. Each zener chain has its own load to provide minimum current through it. There are two cooling fans (120V AC power) which have to be on during zener box operation to avoid overheating of zeners and loads. Power for them is provided by standard 120V outlet plug with cable. Voltages on inputs are the following: #1 (uppermost) - 1380V (Russian FEU-60), #2 - 1270V (Hamamatsu R-760), #3 - 1580V (Russian FEU-60), #4 - 1280V (Hamamatsu R-760), #5 - 1940V (Russian FEU-60), #6 - 1680V (Russian FEU-60). There are control outputs from control dividers for each zener in the chains and loads located on the front panel of the box: 3 control groups with multi-pole switch and 3 BNC connectors in each group. Each load has also separate control output in the bottom of front panel. Normally You have just to check load voltages. If load voltage reading is OK and input HV reading is OK, that means all zeners in this chain are OK. You could also find a table of all control voltages in RICH log book. Control address here is 1-st digit - control group, 2-nd digit - BNC connector in that group, 3-rd number (dash separated) - switch position. HV is entering PMT box via feed-through panel near zener box. A map of this panel is also somewhere in log book. In general just looking on number on zener box cable is enough. Each column consists of two half-bundles, HV wires from all PMTs in the same bundle are soldered to one small paddle card. Ground wires to another paddle card. Paddle cards are mounted on special isolated structure separated from each other with G10 sheets. Two paddle cards for the same column are connected with short jumper wire. Normally HVPS are powered through HV interlock box, which has two interlock inputs from interlock chain inside PMT box. Chain consists of 3 door switches and 3 thermo-switches hidden somewhere between PMT bases. Chain need to be closed for interlock to operate (You could use 50 Ohm BNC terminators for that). When this chain become open, main circuit breaker on the front of the box will trip. Each HV power supply also requires "HV off" input to be close to ground for HV output to be enabled. You could also use 50 Ohm BNC terminator to bypass that. But in normal operation this input was connected to the RICH HV overvoltage protection box output. This box takes control readings from each PS control output and compares them with preset thresholds. If reading is below threshold, output for this PS is close, HV is enabled. Otherwise overvoltage protection trips this HVPS opening this circuit. To restore operation reset switch on the front of the overvoltage protection box need to be operated manually. 3) PMTs and PMT bundles: Each column has two half-bundles, 16 PMTs each, tight together. Each bundle has its own signal paddle card with signal connector (multi-pin EURO type), HV paddle card with all HV wires soldered on it, and ground paddle card with all ground wires soldered to it. Signal cables are RG-58 or equivalent type from each PMT to paddle card. There are 1 kOhm SMD type very small resistors soldered on signal paddle cards as signal loads. It is highly recommended to check them all and replace damaged ones at some point. There are for sure some of them damaged now. This usually happens when PMT sparks or has other HV problems. This signal paddle cards are connected to the backplanes of preamp crates on the top of the PMT box. And they are hold only by its connectors. Russian PMTs FEU-60 are soldered to the bases. They have soft leg wires and can not be detached from the base. Hamamatsu R-760 have usual socket type connection to the base. Spare Russian PMTs which are sorted by voltage and bundle number are in separate envelopes with voltage, bundle (not column!) number, and individual PMT numbers on each envelope. Unsorted PMTs are stored in the folders by batches as they were measured last time. On each folder a list of PMTs in this batch is attached with measured efficiency, noise, selected working voltage, etc. Working voltage for Russian FEU-60 was set to the point with 30 kHz PMT noise, and efficiency was measured at this point. For Hamamatsu R-760 working point was set to the middle of efficiency plateau. Noise from R-760 usually is much less - typically less than 1 kHz. Working voltage for them is also less than for Russian FEU-60. This Hamamatsu PMTs are limited to 1250V by HV. Russians could be run at up to 2000V. Phototubes are installed each inside its own hole in aluminum photocathode plate. They are about 3/4 length deep in that plate. As a matter of holding them just a piece of paper masking tape was used over each PMT for Russian FEU-60, and 3 narrow velcro strips attached to each Hamamatsu R-760 tube. That provides some friction which holds the PMT in its hole. But it is usually very easy to pull it out. So after replacing one tube it is important to check that all neighbors are fully sitting in its holes. Repairing of not working PMTs most likely means just replacing them by spare ones. For this just cut all wires from not working one and solder to the corresponding wires of spare one, then put some masking tape over it, and put it into the hole in the photocathode plate. To protect PTP wavelength shifter coating a very tiny mylar O-rings are installed between quartz window in photocathode plate and PMT surface. It is unlikely that anything could happened with them, but this information is useful anyway. Hamamatsu R-760 are used only in central part of the detector, where Hamamatsu columns and FEU-60 columns are alternating. In total there are 19 Hamamatsu R-760 columns (32 X 19 = 608 PMTs). 4) Preamplifier-discriminator hybrids: Signal from each PMT is connected to preamplifier- discriminator hybrid chip. Cards with them are located in custom made crates on top of the photocathode box. There is one card with 32 channels (hybrids) per each column. There are 3 crates in total, 32 slots each. Only 30 slots are used in each crate, 2 slots are spare (usually right and leftmost slots). Each card has 2 input signal connectors (EURO type), 2 34-pin output connectors for standard 17 twisted pair flat cable, and 3-pin power connector. Hybrids require +6V and -6V. Current consumption is rather big ( ~1.3 Amps per card for -6V, and ~0.8 Amps per card for +6V). Card power inputs are fused, small fuses are located just near power connector. For -6V 2 Amp slow blow fuse is used, and for +6V - 1 Amp the same type one. Fuses are very easy to blow, for example if chip misalignment would occur. Hybrid chips are mounted on individual sockets. There are two types of them with different threshold: 2.5 mkA for Russian FEU-60 and 5 mkA for Hamamatsu R-760. In output chip produces a 30 ns differential ECL pulse for each input signal above threshold. Input signal shall be negative to the ground and not exceeding 0.6V in amplitude. There were several generations of those chips used mostly Russian made. But unfortunately Russian made chips are looking totally unreliable now because of very big malfunction rate. There are also ~500 US made hybrids, which are much better and reliable. LV power is provided for hybrid cards via power lines on crate backplanes. In terms of power slots are connected in groups of 8, each group has separate power entry and fuses. Power is connected to the crates via feed-through rods on the back of the crates. This area is actually pretty unaccessible now. To do so You'll have to remove cooling ducts completely. The rack with low voltage power supplies is near the RICH photocathode box. Usually six 60 Amp 6V power supplies were used (two PS per crate). All PSs are powered through LV interlock box which provides power shutoff in the case of chips overheating. This box was using input from temp sensors system. There were 3 temperature probes installed in the middle part of each crate. If the reading of any of those probes was exceeding threshold, power for the whole LV rack was tripped off by this interlock box.