Minutes of the Tracker Technical Meeting
February 13, 2002
The boxes shipped from SLAC with dummy trays arrived yesterday in Pisa, but without documents. Sandro thinks that with some luck they will have both documents and boxes in Pisa tomorrow. He emphasized that future shipments to Pisa must specify the Pisa airport as the destination. Sandro was concerned about getting the equipment back to SLAC in time for the tests there next week. Tom will check on how long it will take to go through customs in the U.S.
In Pisa they made some exercises with the Plyform trays and the sidewalls. The results look good. They also made measurements on the trays. In most cases the ladders are well positioned on the trays. However, in two cases the ladders overlap because the alignment was lost on the transfer bridge. There was also an accident with one tray, which resulted in scratched ladders (dummy detectors). There is also a problem with the tray thickness. The first tray has the old non-uniform tungsten foils with very thick glue used to even out the thickness. All together this resulted in about 0.6mm extra thickness. The last heavy tray fabricated is close to the nominal thickness, with only 0.2 mm extra thickness at the worst point.
The last tray made by Plyform was done with the light 4-ply face sheet and the light core. Used same tool was used as was used for the heavy trays. They developed a method to reduced the overpressure applied by the vacuum bag to 0.2 atmosphere to prevent crushing (a problem that PCI also had at one atmosphere). Analysis of the two surfaces of that panel showed it to be flat to plus or minus 20 microns.
Pisa is continuing to test HPK wafers. Sandro will send one problematic plot to us. They sometimes find a wafer with good leakage current at 200 V, but the curve indicates breakdown around 170 V. That is, the current starts to rise at about 170 V but still stays below the specification at 200 V. Hartmut said that it most likely is due to one strip undergoing discharge. Since the operational voltage will not likely exceed 120 V, such detectors should be usable.
Sandro said that Luisella has prepared a schedule for tray construction and wants to know when we will ship the materials to Pisa. Tom replied that the first half of the carbon-carbon material is ready to go. Hytec has the honeycomb, and Tom will give them shipping instructions. Twelve bias planes are on Tom’s desk, and the rest should arrive in the next few days (50 pieces). He can also ship the thin converter material, but Tom needs to know how much is already in Pisa. Sandro will check. G&A wants to know when will ship the dummy Si. They want to make all the dummy ladders rapidly in one run. Ossie can ship the silicon wafers present at SLAC. Two more weeks are required to dice the last order of 100 pieces.
Sandro said that he needs to receive again the engineering model schedule, this time in pdf format (their only copy of MS Project being temporarily inaccessible). Robert will send it. He said that their schedule indicates the first tray with kapton and tungsten being completed around the middle of May. (Robert’s schedule had all of them completed before the end of April). The remainder will follow rapidly. They will start carbon-carbon closeout machining around the 2nd week of March. Panel assembly will start March 25. Gluing of facesheets on honeycomb can occur before that. Robert said that we should finalize the closeout drawings while Sandro is at SLAC, which is a little earlier than in Luisella’s schedule.
Sandro asked when the U.S. machined closeouts will be ready? Erik will check with Alcomp on the expected date of delivery of the material. After that he expects about two weeks to machine them. GMSI will run all MCM walls followed by all lateral walls. If not too busy with other orders they may be able to run in parallel on two tools, in which case there would be a possibility of shipping complete sets of closeout pieces before all of them are machined.
Responding to Tom’s question, Sandro said that Plyform will have two panel assembly tools for the engineering model, one for heavy trays and one for light trays.
Tom reported that NASA Goddard is working on getting a contract together with NASA Ames for the tower vibration. Looks like it will be a go for February 25, 26, 27. Tom said that he will arrange a visit to PCI on the 28th (note: we are now discussing changing this to a visit to GMSI).
Tom said that he plans to travel to Pisa and to Plyform the week of March 11, along with Bill Althouse, Ossie, and Steve and Erik. He is thinking to be in Pisa the 11th and 12th, travel to Milan on the 12th, and then work at Plyform on 13-15. The main topic will be to review the final tooling and procedures for the panel and tray assembly.
Hytec issued a report on alternative sidewall materials being considered for reducing the thermal drop down the tower. All agreed that we probably should go with the less expensive K13 material, instead of K1100. The latter is expensive, has a long lead time, and would require a lot of new engineering and test work, due to the fact that it has less strength and is not available as a weave or in thin plies. All that for only about a 1 degree reduction in temperature drop compared with K13. Erik and Steve strongly recommended doing some tests on the new material, so Erik will try to reserve a test panel of the K13d material that he noted is immediately available.
Tom said that he has put in a change-order request for flight carbon-carbon material. The issue is that the present plan in the PMCS system calls for Italy to make the purchase, but the funds are not available whereas procurement needs to start now. This will needs an action from the Change-Control Board. Tom will bring it up in the project meeting today. Part of the deal is to make a trade, such that Italy will purchase the sidewall material. Tom looked into the schedule and noted that the closeouts are needed in September. Given our experience with Alcomp, the order needs to be started as soon as possible in order to avoid possible delays.