Subject: Time: 9:53 AM

OFFICE MEMO cooling minutes 6/5/98 Date: 6/8/98

To: Debuncher/Accumulator Cooling AIP Distribution

Subject: Meeting Notes 6/5/98

Electronics

Miteq has been contacted and will deliver once piece of the band one cryo amplifier by the end of June. A bid for high power 4-8 GHz 180 degree hybrids was received from Narda. The unit cost is $980 due to the $40K for NRE that is included in that cost. Narda has a lot of high power experience and we are running short on time and resources, hence the order was placed.

The order for PLCs has been placed and all of the hardware has been delivered. We have decided to locate many of the PLCs in the tunnel to minimize cabling costs. Experience with PLCs on the PET project have shown them to be robust in a radiation area. The Pbar tunnel is less radioactive than the PET linac.

Charlie Briegel, Dennis Nicholas, and Mike Coburn represented the controls department. Mike reported that the hardware for TWT protection computers in AP30 and 50 are out on bid. Hardware could be available in 6 weeks. Dennis has a head start on the software and is waiting for the hardware to begin testing. Charlie reported that there are a number of ways to connect to the PLCs. Bob Goodwin has code written for IRMs that handle the interface. This code could be translated for the VME platform.

Dave Peterson has found a new RF detector that is based on a thermistor. It appears that the device will operate up to 8 GHz and has a linear power transfer curve. A sample is being procured for testing. If the unit is as good as it sounds, all diode detectors will be replace with this device. The cost for the part is between $10-$20.

Mark Champion has been testing the pickup hybrid at LN temperatures. There is a marked improvement in insertion loss. Mark needs to check that his calibration utilizing a cold connect through for the calibration.

Jay Theilacker reported that the transfer line in the tunnel is nearing completion up to the feed can. The feed can itself is 60-70% complete. Design of the vertical transfer line between the surface and the tunnel is 20% complete. Lack of welders continues to be a problem. The cryo group has two welders assigned, but one of them is routinely pulled away from the Debuncher upgrade. Additional welding for the stacktail tanks will also need support.

The two low band pickups will have the aperture increased in an attempt to reduce the amount of absorber required. This change will have an effect on the amount of cryogenic cooling required. Arkadiy Klebaner and Dave McGinnis need to get together to address this question.

Mechanics

Bob Vargo and Chris Kelly are busy assembling the 20 stacktail kicker arrays. Joel Misek reported on the design of the stacktail arrays. The design of the ground plane for the pickup arrays is nearing completion and will be out for manufacture within a week. A screw will be added near the termination resistor to insure the best possible cooling.

2-4 & 4-8 GHz R&D

Dave Peterson and Paul Derwent will do a careful calculation of the front end noise temperature budget for the stacktail. The current design will utilize 0.141" coax for the secondary combiner. If necessary, there are a sufficient number of 2-4 GHz cryogenic amplifiers to put one on each array. This change would also require an additional 10 trombones that we do not have. A decision on performance tradeoffs will need to be made.

Don Poll has a quote for the stacktail pickup arrays. A prototype will be done first for $3200. The full production run will cost $21K for 40 pieces. Delivery is expected to be 3 weeks.

Dave McGinnis is looking into a Debuncher band 1 & 2 kicker design that will open the aperture and remove 90% of the absorber. The larger aperture will make the beam pipe a waveguide below cutoff for those two bands, hence requiring less absorber. This is being done in the interest of solving the vacuum problem.

Ding Sun has been working vigorously on solving the Debuncher absorber vacuum problem. His latest tests show very good results with Aluminum Nitride doped with carbon or ferrous material. For 50 Watts incident on the test fixture, only 5 Watts are transmitted for 10 dB insertion loss. The vacuum remained 4x10-7 Torr. A new material with Aluminum Nitride doped with 40% SiC from Seradine Corporation will be tested once a sample is obtained. The MF 190 absorber will be used exclusively in the pickups.

The new stochastic cooling tanks for the Debuncher required the removal of several trim magnets. Al Sondgeroth has been working on a lattice design that will require 3 vertical and 2 horizontal movable stands for moving quads.

Optical Signal Transmission

A new photo diode from Hamamatsu has been obtained. This device has been measured to have 9 GHz of bandwidth. It achieves this performance with a 200 by 200 micron active area. The focused laser beam was measured to have a 100 micron cross section by performing a razor blade scraper scan. Tests have shown a 3 dB optical power sensitivity vs. position of plus minus 125 microns. The fiber based receiver had a position sensitivity of 2-3 microns. Sensitivity to receiver position has now been eliminated. The laser link has been measured to have 35 dB dynamic range when loaded with noise over a 1-4 GHz bandwidth. This device will be mounted in the Accumulator tunnel test so that data logging can begin.

Administrative

A gant chart for tracking the Debuncher upgrade was distributed to the electrical, mechanical, and cryogenic groups. This chart should be checked for accuracy and updated in the next week. Ralph Pasquinelli will compile the data and keep it up to date.