Minutes of the Tracker Technical Meeting
August 1, 2002
This meeting was held Thursday morning, rather than Wednesday, because of a conflict with the delta-PDR review in progress at SLAC.
Sandro presented the status of ladder production at G&A: 40 live ladders are glued together and have been measured. They are wire bonding now. Sandro has the fin results from metrology: 3.5 micron rms error, with a maximum error of 15 microns. The bond thickness ranges from 7 microns to 60 microns with a 31 micron mean. Most are in the range from 20 microns to 40 microns. See the attached histograms.
They have tested bonded 20 ladders electrically. 5 strips are bad that were not already declared bad by HPK. They look like broken caps. This is a 0.065% rate.
The bad news is that there is one ladder with very high leakage current. It starts to discharge at 50V and reaches 10uA at 200V. A second ladder goes from 550nA for the sum of 4 SSDs before assembly to 1.6uA after assembly. They will check individual channels on these two ladders to try to isolate the problem. The other ladders increase more in leakage current than expected, based on earlier testing. Typically the current is doubled. INFN workers are at G&A today and tomorrow checking the system for possible problems to explain the anomalous current. See the attached plots.
They plan to encapsulate the ladders starting August 26, as G&A will close next week. Sandro will probably be away on vacation Aug 9 to Sept 2 but will finalize plans this week. Luisella and Ricardo will be available last 2 weeks of August.
Top/Bottom tray material: it should arrive at SLAC from Alcomp by August 20 (earlier for the top tray). Tom needs to call to check on this.
Top/Bottom tray panel assembly tooling: BJ will post the drawings. There are 2 pieces that must be different for the bottom tray, with respect to the top. They need to be reviewed quickly by Luisella when she returns the 19th Aug. They will take about 3 weeks to build. SLAC will QC the tool before shipping. Sandro said to measure the tool after assembly, as they found some surprises there in the standard tray tooling. SLAC should ship by 16 September.
Mid-tray panel assembly: only 4 trays panels have been made so far, as they have been working on correcting the tooling. Real production will start August 26 at a rate of 2 trays/day.
Assembly of tungsten onto panels: This will go parallel with panel assembly. The first week of October the trays should be finished with Tungsten & Kapton. 2 weeks are required to glue ladders, plus one week to wire bond.
Fabrication of the Kapton assembly tool: The tooling has been ordered for both tungsten & Kapton.
Order of extra connectors: in progress. Robert and Dave are working on ordering more for the test systems and burn-in system.
Fixture for wirebonding trays: Sandro said that a mockup tray is at G&A, along with the electronics mockup. They are working on the fixture for the Delvotec 6400 wire bonder, which has a moving head. The jig will position the tray in 4 positions to wire-bond 1 ladder at a time.
Sidewall machining: Tom will schedule this. It is needed in October.
Tower lifting fixture: design is in progress. There will be an adjustable one and a simple one. The adjustable one is for installing towers into the grid. A 3rd fixture with fiducials (tooling balls) is being designed for measuring alignment. The simple fixture is sufficient for the EM.
Tower assembly fixture: SLAC is studying the issue of how to attach flexures to the module with adequate alignment. The idea is to make the needed fixture part of the tower assembly fixture. For that they need more space at the bottom. Hence they will raise the support walls about 5cm. They are refining the design with Nordby et al. The goal is to have drawings for Luisella when she returns.
Thermal gasket redesign: there was some discussion yesterday and will be some discussion with NASA today. Some test data from Jeff Tice on samples is in hand. One issue is whether to mount the gasket to the Grid or the Tracker. Another is whether to put adhesive on one side or both sides.
Flexure-mount analysis & redesign: Analysis is in progress at Hytec. Tom will be in Los Alamos next week with ART members for discussions of the model.
Sandro reported that Ricardo is working on ultrasonic testing of trays at a company in France. They have high enough frequency to detect the thin facesheet. Another sonic system is being investigated near Rome, with stimulus from tapping rather than transfer of energy from the air. A third is an interferometric system in Frascati, similar to the Hytec system. It detects movement of the parts in a thermal cycle.
Tom said that we need to start working on flight procurement of tungsten foils.
Also, the closeout material PO has been let to Alcomp, with the first lot to be delivered in late December.