Minutes of the Tracker Meeting
October 16, 2003
Darren said that he wants to see an NCR for the honeycomb core issue.
Sandro reported on the core inspection. They measured the weight of each honeycomb core and inspected them in Pisa before shipping to Plyform. The defect was noticed there. At Plyform Sandro looked at it for the first time and made the photos. Each core has a serial number. Sandro will write an NCR with all the info, and then Tom will approach the vendor about the issue.
Erik reported on the flexure qualification static test. They pulled at 45 degrees to 100%. No issues were seen, and the data are clean. They only pulled in one direction, which puts some flexures in compression, others in tension. Two flexures have shear load with tension and 2 with compression. This satisfies the requirements, but the other case will be done for completeness.
Jack will meet with Jeff Wang before next Thursday to go over the thermal-vacuum issues. Nanda said that we need to include considerations of temperature control requirements of the TEM/PS (not an issue for the EM, which will not have a TEM/PS). Sandro needs the instrumentation plan soon to give to Alenia. Also, we need a list of test cases (power levels, etc). Nanda will be back at the end of the week after next. In the meantime, Jack will make a first cut at the instrumentation and test plan.
Erik said that he had talked to Steve about predictions for the vibration test plan. We want to have response curves at each accelerometer location. For that Steve has to re-run the analysis. First they will review the accelerometer plan. They also need to define the strain-gauge locations.
There was a discussion of support of the flex-circuit cables in the EM, especially during vibration. The plan has long been to put 3M transfer adhesive between the cable and structural closeouts, such that the cable gets clamped tightly between sidewall and closeout. Sandro will evaluate how to add tape between the cables and closeouts in the already assembled EM tower.
Then there was a discussion of insert preparation for bonding into closeouts. Tom worried that primer on the inserts would add about 100 microns to the insert diameter. Sanding is another possibility. A higher strength adhesive might also be used. Sandro said that inserts were sanded during installation in all the EM closeouts, and curing was done at 85C for several hours. Inserts are checked after the 85C cure. Sandro needs to check that this procedure is documented in the procedure. A completely new procedure document will be made for the bottom trays.
The discussion moved to coordination of test-script development for Tracker towers. Hiro said that he had talked to Johann about the problems, and they came up with list of things to correct. The worst problem is a lot hard-coded parameters. Code cannot be changed during testing of flight hardware, so parameters that might need changing cannot be hard coded. Each parameter should have a default in an XML file and a GUI should be available by which to change the parameters during testing. The program must log all such changes automatically. Another problem is widespread duplication of code fragments. Hiro wants to eliminate these by coding them as subroutines. Also, there are different scripts for layers versus towers. These should be able to use the same code, with capability to choose between testing a tray versus a whole tower. It was decided to have a kick-off meeting at 8:00 am Monday, October 27. Luca Baldini will do the minutes.
Luca Baldini reported that Pisa has a working TEM and mini-tower cables now, so they are able to do some code testing there.
Sidewall fabrication status: COI has cut out all of the panels and coupons. They have drilled several full size panels and done CMM, with good results. They just received inserts for coupons this morning, plus screws. They will do all the mechanical tests. Thermal test coupons will be sent to Hytec. COI will have tension and compression tests on panel material done by the end of the day Friday. Insert coupon testing will be done next week. There are not enough inserts for the short panels. Plyform does have enough inserts and the tool for installation, so we will wait for Plyform to provide the short sidewalls for the static test. Plyform is still waiting on the aluminum and primer. Nothing arrived as of today. Plyform can supply the mini-sidewalls 2 weeks after receiving the material. Jeff will track shipments.
Tray panel status: Plyform has machined the first group of 40 CC closeouts. They will measure them and then send them to Pisa for crosscheck. Tools for assembly are practically ready for mid trays.
Robert reported that we have been holding daily meetings with Teledyne. The boards have finally been machined successfully to specifications, by an outside machine shop. All the remaining parts will be shipped Friday from SLAC to Teledyne, so Teledyne can start making up the kits for assembly. Teledyne is modifying the flex-circuit trimming tool to account for the offset caused by addition of Kapton to the backside of the board. They have also successfully tested a method of trimming the two short ends of the flex circuit. The new method is to trim them to length before gluing. Teledyne is making a die and fixture to make this cut during production. It looks like the earliest start date to have all of this together to begin production is next Thursday.
Robert reported that the present GTRC cannot operate at 20 MHz without skipping clocks. As high as 18 MHz looks possible if the voltage is raised up to about 3V. A new GTRC design is in progress and will be done next week.
Darren said that he needs an NCR on the GTRC issues.
Tom reported that the M55J pieces are made at COI and cut to raw size. The next step is to laminate the CC. They resawed the CC to make 2 from 1. They will make 98 assemblies to have spares. The remaining CC arrived from Italy and is ready to ship to COI. Purchasing is awaiting release of the drawings.
The order for corner brackets and flexures is sitting on Jerry's desk. It is waiting for drawing release.
SLAC needs to know the resin used for passivation of the carbon on closeouts and trays. This is holding up release of assembly drawings. SLAC also needs to know exactly where the resin is applied. Nanda will find out and send email.
Samples of M55J and CC are needed for outgassing tests.
Shipping container status: assembly of a mass model is in progress at SLAC to simulate the tower in its inner shipping container. Humidity/temp/shock monitor will be put in, and they will do some drop tests of the shipping container with mass model at SLAC. They will then ship it to Italy with the monitor and mass model. The timescale is a few weeks. BJ will send the container drawings to Nanda.