Minutes of the Tracker Technical Meeting
August 21, 2002
1. Luisella: review of BJ's drawings
2. Status EM tower activities
3. Status of ladder preproduction review and documentation (Travelers!)
4. Robert/Tom: visit to Teledyne
5. Robert: ASIC status
1. Sandro: send Robert contact names for working on ladder assembly documentation
2. Luca: send the traveler pages to Robert
3. Luisella: review the tooling drawings done by BJ
Sandro reported that the ladder production on hold due to the issue of cleaning. AMS has the same problem. They claim to have a good storage method using Tyvek foils, so Sandro will look into obtaining clean Tyvek material. He also is talking with HPK in Italy about another possible solution. G&A plans to finish encapsulation of ladders for the EM next week. They will be tested again before encapsulation and then afterwards.
Sandro will be away next week but will send Robert some contact names to work with on the ladder documentation. Robert emphasized that this production start has a high profile in the project, as it is the first assembly of LAT flight hardware. It is imperative to get the documentation reviewed and signed off before the production start. To this end, Luca will print the traveler pages and send them to Robert.
Luisella has returned from vacation and has looked at some of BJs drawings. She requests some small modifications. There is an issue with the honeycomb thickness in LAT-DS-647 and with the tolerances on tray size in LAT-DS-207. She requests the same tolerance reported for normal trays for all others. The point is that the tray length is not the same as the closeout wall length. Rather, it is determined by the assembly fixture. BJ said that he already updated this. BJ will call Luisella tomorrow about tooling drawings, as SLAC needs to move forward on getting them machined.
Sandro said that they would like to move the ladder electrical testing after encapsulation. They believe that they can verify with the first 40 ladders that no repairs are necessary following the wire bonding. That is, the rate of repairable faults is so low that there is no point in making the effort to repair them. Furthermore, doing the testing after encapsulation has several advantages. It results in less handling steps, and the handling for testing is done with an encapsulated ladder, which is more robust mechanically. Also, it is desirable to do a final test, in any case, before putting the ladder into storage. Robert said that this revised plan sounds okay but stressed that testing must keep up with the production to get quick feedback on the process. If something went wrong in the process, no repairs would be possible on already completed ladders. Sandro said that they have the plans and infrastructure in place for the testing to keep in pace with the production.
Tom said he talked to Alcomp, and the new material should be Alcomp's hands today. It only needs another day of processing. Probably Tom will get it at SLAC mid next week and then will ship it to Pisa. He emphasized that the size is different for top vs bottom trays! Also, there is only one spare piece, so great care must be taken in the machining and handling.
Tom estimated that by the first or second week in September, the tower analysis should be complete enough to know how to machine the bottom tray closeout, even if the details on the flexure and corner bracing have not yet been fully worked out.
Robert reported on a meeting that he and Tom had with Teledyne last week. Complete minutes, with some 20 action items, are on the Tracker web page. First 2 prototype MCM assemblies need some rework to add adhesive where there are voids under the wire-bonding area. They should ship to SLAC this week, then Tom will send them to Pisa. Teledyne will make some more samples like this for wire-bond testing. The 45 thermal boards for the EM should be done by mid September, and the 13 live boards should be done by the end of September.
Robert reported on the ASIC status. Four different chips were manufactured:
1. GTFE with AC coupling to the comparator.
2. GTFE with DC coupling to the comparator.
3. GTRC with 32-hit/event memory made from flip flops.
4. GTRC with 64-hit/event memory made from RAM cells.
All four chips appear to be fully functional, although the testing is not very complete yet. Chips are being tested individually and in mini-MCMs. A mini-MCM loaded with all four chip types has been shown to read out in both directions at >20 MHz.
SLAC will assemble soon a full-sized MCM (without pitch adapter) to test the signal transmission on the board from GTRC to 24 GTFE chips.