Minutes of the Tracker Meeting
July 1, 2004
1) Nicola et al: status of the T/V test preparations and thermal stabilization of the TEM/PS:
Nicola reported that in Bari there is a web page for Tower A T/V. Drawings of the test hardware will be available next week, including a configuration drawing of the test setup. The solid model can be seen on the web page. The long TEM cable is in Pisa to label the wires, since SLAC did not label them adequately. Procedures for the T/V test are in progress. Nicola expects to use the same team as for the EM test.
Nicola asked whether the SSD bias can be turned on at the max temperature of 50C, to perform a CPT. Robert said that although the test may not meet noise requirements, there should not be any danger of damage from the leakage current, which would be about 8 times the room temperature current. But he wants to verify this with Si experts.
The long PDU cable for T/V testing is missing. Pisa will check for it in customs. Jeff will ship over two more.
2) Tower functional test preparations and support needed from SLAC:
Luca said the need the C0 cables, they have 2 test stands working and 2 more in customs. Robert reported that just 6 C0 cables will be sent, with connector savers. 3 others had to be returned to Parlex because of manufacturing defects.
We identified a need to have a cable tester in Pisa. Robert will look into what SLAC can send.
For the test support Pisa needs some people from online, such as Rick or Selim, plus maybe 1 from the electronics group. Persis will check on availability. The best time for them to be there is when the tower is assembled.
Luca reported that the stacked tray and tower level test procedure documents need updates and release. He and Hiro and others are still discussing feasibility of a couple of performance tests that may be better performed at SLAC after tower delivery. Persis recommended that we identify a minimal set of tests that absolutely must be done before environmental test.
3) Martin: Lifting Fixture configuration change
Martin explained his reasons for changing the design back to the flexure concept. We cannot tolerate having shoulder bolts bearing down on the inside of the top tray closeout. The shoulder on the shoulder bolts was actually smaller than the hole for the inserts, meaning that the shoulder would bear down on the epoxy at the end of the insert and have an unknown effect on the insert and bolt. We could add a bearing plate on the closeout, but that seemed like a poor fix to the problem. Martin incorporated Emilio's suggestion to use bolts running vertically, loaded in tension. This also allows one to adjust the flexure position to minimize the amount of flexing. Flexures can be installed first onto the tray and then put on the plate, if needed. There are 4 lifting eye nuts around the corners and 1 more in the center. Martin added balancing weights, which are optional. He and John will complete the stress analysis today.
Tom Venator offered help from the Goddard shop to make some of the MGSE.
4) Dave: Request fit check of MJ2.5 x .45 x 120 Counter sunk screw into Aluminum and Ti. Inserts to ensure fit with M2.5 female thread. We successfully performed a fit check of the MJ2.5 x .45 x 120 Counter sunk screw into a M2.5 commercial nut and there were no issues with interference. If Sandro's fit check works as well, I would like to claim victory and use existing qty. 13,500 screws that INFN has for flight:
Dave said that the J denotes a special root thread form (softer radius), but they found that the threads worked fine in a standard nut. He Would like Pisa to check these screws in an actual insert (Al and Ti). It turned out that that had already done, with no problems found.
100 degree screws: Jeff located a supplier and hopes to have them a week from Friday. Martin will release drawings of the screws.
Pisa also needs Torx+ screwdrivers. Robert suggested getting screwdrivers with a built in calibrated torque setting.
5) Dave: Discussion of INFNs Tower Turn-Over Fixture. Understand concept and required interface.
Emilio said that the info on this fixture is in the procedure. It is to be used after installing the grid simulator and cable plate. The CPT tests will first be done with the tower upside down.
The rotation tool is in production. It attaches to the grid simulator and cable plate with 8 bolts. They will send drawings to Martin, including 3-d pictures.
Martin needs more info about the asymmetry in the grid simulator that was noted by INFN. Marked up drawings would be best. It was noted that the existing fixture used for the EM vibe must have this asymmetry, since it was built to those drawings (or the solid model from which the drawings were produced).
An analysis and proof load test of the turn-over fixture is absolutely required. John Ku can review the analysis.
6) Dave: Closure on Inner container design.
We decided to hold an 8:00 meeting Friday; Dave Rich will send out an agenda and call-in number.
7) Martin: What bottom tray grounding lug is being provided?
Sandro will go to G&A tomorrow and check on the status. Martin will release the drawing today. Material is in procurement at G&A but nothing built yet.
8) Sidewall fabrication: release of the spec document
Defered until Riccardo's return from Plyform.
9) Tray assembly at G&A: release of the drawings and procedure spec
Sandro has reviewed the drawings. He had a few comments, but I think the conclusion was that they can be incorporated as redlines or in the next release.
Sandro said that the encapsulant height limit should be 0.7mm. This is higher than the requirement on ladders because very little dynamic clearance is needed near the tray edge, and there is no opposing encapsulation line at the location on the tray above.
10) Tray panel assembly at Plyform: schedule projections for Tower A and mass production
Sandro noted that there are 2 problems preventing start-up:
- Kapton bonding issue
- Bias circuits. Robert emphasized that there is no quarantine on any of the bias circuits, so that should not hold up start of production. However, to minimize risk in using circuits in parallel with NASA coupon testing, the circuits should be used first-in-first-out.
Sandro said that the last shipment of circuits is stuck in customs; there is a problem with serial numbers.
Tom had some questions:
- COI certs. Dave said that the certs were faxed to Plyform yesterday. A duplicate was forwarded to INFN.
- Hex nut locking mechanism. Arthur is picking up studs and verifying that they work with the patch, using actual hex nuts. Any change of the design to use epoxy instead requires consultation with I&t.
- TQCMs for thermal vac: has SLAC agreed to purchase them? Robert will talk to Jack about this. Nicola said that there may be an issue of feedthrough availability. He will check on that.
Nanda said that we need to schedule a new delta-TRR for the bottom tray static test procedure to review a couple of changes identified as being needed.