Minutes of the Tracker Meeting
May 23, 2001
Robert reviewed the PDR preparations. A presentation schedule was put together with David Lung:
Tracker PDR Presentations:
Total Scheduled Time: 4 hours and 15 minutes.
It was decided that it would not be necessary for anybody to travel from Italy for the review. The review will be held at SLAC in the Orange Room. It should be possible to get VRVS hooked up there, so that others can participate. However, all presentations will be given by people actually in the room. Erik and Steve will travel from Los Alamos.
Ronaldo reported on the Grupo II meeting held recently in Rome. It went rather well, and they are approaching formal approval, probably next month at the plenary meeting of Grupo II. The committee appears to be very favorable toward GLAST. GLAST was funded for one probe station for wafer testing in Pisa. A 2nd is in the queue for Trieste. Two more are planned for ladder testing. Regarding the MOA there was a meeting with INFN. They proposed small changes but are essentially ready to sign after formal approval takes place.
GMA and Mipot are concentrating on ladder production. Already there is good success with encapsulation at Mipot. GMA is starting to work on encapsulation. Pisa is almost ready for dispensing of glue on trays (tooling and programming in progress).
Luca reported on progress on database for production. He is making a MS Access prototype and is working on a web interface to do queries. He is also preparing some documentation and will some information before next week’s meeting.
Ossie reported that he is carrying out a thermal test on a ladder of blank Si wafers glued to aluminum. The strain is only a little higher than with a single wafer, and there is no increase in strain from center to end.
Erik reported that they placed orders for honeycomb, fasteners, and inserts. Also, he placed RFQs for sidewalls with PCI, COI, (and soon to YLA) for 9 panels and for 80 panels. Also, there is an RFQ out for assembly tooling with GMSI. They received reimpregnated slices of material from Allcomp and sent them to GMSI to have them machined into closeout sides. GMSI will try to get them on their machine Friday or Tuesday. Hytec cut one piece, and it looks good under magnification. Hytec rechecked the thermal analysis with 0.35 W of power assumed per MCM. Even with worst-case conductivity, they get 11 to 12 degrees drop over the tower, which fits the budget. Tom would like to see published a breakdown of the temperature drops. Erik will look into incorporating this into the report in progress for PDR, but he said that most of it is in the wall panels. Erik will get the PDR document done next week.
Regarding EMI shielding: PCI and COI both will co-cure or post-bond aluminum foil to the panel at a fraction of the cost of vapor deposition. Thickness can be whatever we want. 50 to 100 um is fine. Do we need to run the aluminum down into the countersink? If so then we must post-bond, but forming the aluminum into the countersinks could be labor intensive. A dab of conductive epoxy on the screws is needed for retention, so Tom suggested to make it conductive epoxy to make the contact to the screws? Erik prefers co-curing, which would be allowed in this scheme.
Hartmut talked about the BFEM Tracker readout problem. Could the Pisa group try to reproduce the error with their two trays? UCSC has just one tray, but Wilko is sure that the problem is a multi-tray issue. Wilko thinks it will be very difficult to reproduce the error with the existing benchtop system. One must read very fast and fill and read out the fifo very fast. Then one must detect the error. The TEM used in the balloon flight is different. Even if it could be reproduced with the TEM in Italy, that would not tell us anything beyond what has been learned with the BFEM hardware. It would be better to use a logic analyzer to have complete control of the timing in order to understand what is happening. It was decided that we cannot justify the manpower for such an exercise. Since the new GTRC is a complete ground-up redesign, finding a timing problem in the old version would be of no help and could not be fixed in the BFEM anyway.
Robert reported on the electronics. Layout is in progress on the mini-MCM and on the readout cables, with the first nearly routed. Tom still has no quotes on MCM fabrication. He will phone today. Tom talked to SLAC procurement people about POs to Teledyne.
Mauro said that he will have a 2.5V / 1.5 V prototype Tracker power supply ready in July. Robert said that there will be no Tracker electronics to test it on until late this year, so Mauro will concentrate on testing it with dummy loads. Robert expressed concern about how this effort fits in with the overall LAT power-supply effort. Mauro said that he is in communication with Gunther Haller, who manages the subsystem that includes the power supplies.