Feedthrough Meeting 06/02/98 present: P. Birney, M. Fincke-Keeler, A. Humphrey, R. Keeler, R. Langstaff, M. Lefebvre, P. Poffenberger - News from LAr week at CERN Michel distributed copies of the transparencies presented at the feedthrough meeting held in CERN on 26/01/98. The interface region between the endcap cryostat and the feedthroughs was discussed. A drawing from A. Fallou was distributed, showing the new layout with more radial space between the warm vessel and the cold vessel. Sufficient space is reserved for the operation of an automatic cutter (if the removal of a feedthrough is required), or for the operation of an automatic welder (for installation). A standard CERN orbital cutter was assumed. Provision is made for up to 3 cutting operations, as each operation removes 2 mm of funnel tubing. It is planned to install the bellows prestressed (at warm) by 8 mm. This then becomes 2 mm at cold. In the event of a repair involving cutting the funnel tube, the following reinstallation would result in the bellows being relaxed at cold. A protective sleeve is required during installation and repair, to avoid damaging the cables. The exact nature of this sleeve is not yet fixed, ideas welcome. Terry's work on the low voltage vacuum cable temperature and current issues was presented at CERN, and given to Jurgen Fent. Margret and Jurgen have also discussed the issue at CERN. Our German colleagues are proceeding with the low voltage distribution in accordance. Various comments were made concerning the design of the low voltage vacuum cable. Jurgen Fent pointed out that both traces (the signal and ground traces) could be used for the power transport (our current design only uses the signal trace for power transport, while the ground and signal traces contribute to the heat transport). This would result in half the current density, but requires some design changes in the strip and connector (the ground trace would need to be connected to the signal trace, and disconnected from the ground of the connector). Alan Honma also commented that we should investigate the use of conventional cables (ie not a strip design) for the low voltage cables. Terry pointed out that the idea to keep a strip design is mainly to ensure mechanical compatibilty with the other vacuum cables upon packing and movement in the bellows. Pierre Imbert reported on the status of the pigtails cables. Cables were ordered last summer for the test cryostats (EM barrel and endcap). The propagation time variance was found to be unacceptable, and the cable production was halted in October 1997 to further study the problem. Imbert reported that the requirement was 2 ns/m while a value of 3 ns/m was measured. [Michel notes that other numbers are also heard, namely a requirement of 1 ns/m from Walter Bonivento, and a measured value of 5 ns/m for some cables]. The problem is understood to be caused by Axon use of glue (called HKJ) in the manufacturing of the cable. Axon is now trying new cables without glue, first results expected in February. If these new cables do not satisfy the requirements, Axon has agreed to buy the cables from Filika, before putting the connectors. The Filika cables are known to work from experience with cables for Babar. - Pin Carrier Status Quotes were received from PCT. They are twice as high as expected for a small order (we require 10 for Victoria and 10 for BNL). Terry has contacted Dan Harper at PCT for explanations. Dan Harper said he would look into it. It was felt that we should wait for Terry to finalize his engineering discussions with Dan before Michel or Dave contact him. Quotes from Glasseal are expected anytime now. All this means that the pin carriers are not ordered yet. Delivery time for PCT is 1st unit in 14 weeks, from time of order. - Bellows and Flanges Roy and Dave Rahm will visit the BOA bellows company Thursday February 12th. Roy is confident that the bellows issue can be sorted out then. We all wish Roy a good trip to Atlanta. The warm flange design should also be finalized as soon as the bellows details are understood. Roy reported on his proposal for the warm flange port threads, and other improvements on the warm flange drawings. See distributed email. - Leak Test Setup Status Paul reported on the status of the Leak Test Setup. Pumping of the warm side of the setup will start next week. The ion pump is connected. The RGA and the gauges will be installed soon. Wiring for the valves is near completion. Thanks to Pof's help, an 8 channel temperature probe with set point relays has been ordered, along with 8 Si diodes. It was pointed out that we need to review our need for RS232 ports for our DAQ PC. Paul reminded us of the various RS232 port types (25 pins, 9 pins, 16bit, 32 bit). Paul is to draw up a list of the currently known RS232 ports required for our hardware. We should then talk with Michael and plan the appropriate action (ie more ports for eddie, or adequate ports for the next PC we buy). - Model Paul presented a final drawing of the mechanical components of the model. It was decided that the bellows ring be made of wood, as this will not affect the overall weight of the model given that the fake bellows is heavier than the real one. Work is starting at the shop. Margret reported on the status of the dummy vacuum cables. The plastic material is in hand. Dummy pigtail cables also need to be made. Many options were discussed. Margret and Paul to finalize a proposal. Michel remarked that it may be desirable to have these cables done before Margret's next trips (Ottawa and CERN). Richard and Michel offered to seek manpower for the production. - Refrigerator Status Alisa reported on the status of the refrigerator project. The cryocooler cooling power is now believed to be 87 W. Alisa's heat calculation show that this is enough for the expected heat loss through the feedthroughs. Material for the refrigerator has been ordered. The design of the stand is near completion. Vacuum valves have been ordered. - Vacuum Cable Status Margret reported on the status of the vacuum cable project. She met Walter Bonivento during the LAr week at CERN; he is working on the pigtail cable requirements. He mentioned a desired requirements of 0.1 ns/m and 0.25% for the variances in the signal propagation time and attenuation respectively. Margret is in the process of understanding what this means for the vacuum cable manufacture. Preliminary estimate shows that this translate to a variance of 5 mm in trace length over a strip. Margret is to verify what is the actual trace length variation for the current design. Margret reported that our cable desing currently produces 5% attenuation at 10 MHz. We need to find out how to estimate the attenuation variance for our cable design. Margret is also looking into how to measure these cable properties with our equipment. Ernie Neuheimer has been investigating the type of soldering to be used. Stips are expected to go to AMP for crimping any day now. Ernie is to assemble both connector types himself. The question of noise entering the cryostat through the low voltage lines was discussed. It was reminded that the low voltage lines were not shielded lines, that is nothing will connect from the lines to the pin carrier body. It was noted that the RF seal located on the aluminium bolt flange was meant to ensure a noise free volume from the warm flange up to the electronics crate. - Computer Order Status The PC for Alisa is now operational. The ATLAS PC count is then the following: borg: Server PC (on Michael's desk). (MIG) eddie: PC currently in ATLAS lab. (MIG) hepcad: PC for CAD (on Alisa's desk). (MIG) ?: Perhaps another PC for the ATLAS lab (MIG) ?: Soon a portable PC for management (Michel) (MIG) higgs: PC on Michel's desk (Operating) There are also other non ATLAS-paid PC around: trilab2: Paul's PC design: Roy's PC hep: Richard's PC - ATLAS meetings and other important dates - Feb 15 - Feb 21 : Lake Louise Winter Institute - Mar 02 - Mar 06 : ATLAS week - Mar 09 - Mar 13 : LAr week - Mar 29 - Apr 04 : ATLAS Physics workshop, Grenoble - May 04 - May 10 : LAr week - Jun 08 - Jun 12 : ATLAS week - Jul 06 - Jul 10 : LAr week - Jul 23 - Jul 29 : ICHEP98 "Rochester Conference", TRIUMF - Sep 04 - Sep 18 : ATLAS week - Sep 21 - Sep 26 : LAr week - Nov 12 - Nov 18 : LAr week - Nov 16 - Nov 20 : ATLAS week