Minutes of the Tracker Technical Meeting

February 28, 2001

Present: UCSC, SLAC, Pisa, Trieste, Hytec

Robert reminded us that the Tracker PDR is scheduled for May 30, 2001. He said that he and Tom had listed the tasks required for PDR preparation and assigned names of the responsible people, along with deadlines. It is largely a matter of getting the documentation put together for the planning, design work and testing that has been done so far. Robert will tidy up the list and contact the responsible people. It was noted that the documentation for the PDR should be given LAT numbers and put into Cyberdocs.

Ronaldo said that on the Pisa web site are plots of results from testing and HPK detector with Premux electronics and a Ruthenium source. There are plots of beam profile, S/N, cluster width, and so forth. The results generally look good. He noted that the noise level of these fast electronics with one detector is probably similar to that of a GLAST ladder with GLAST electronics. They measured the leakage current after each assembly step (wire bonding and so forth) and found no degradation from the initial 70 nA value.

Gwelen showed results on testing the adhesion of Nusil silicone conductive adhesive to aluminized silicon and gold-plated pads. (See attachments.) The primer was found to increase the strength of the bond in a pull test by at least a factor of 10 (the samples with primer broke at other points besides the silicone, so only lower limits on the strength were obtained). He also noted that the electrical conductivity is fine with the primer. In fact, Nusil says that the primer should improve the conductivity of the join. UCSC is now testing some live detectors with the primer in a long-term test to check for possible incompatibility.

There was a discussion of connector saver length. Sandro said that they are designing boxes to hold the trays which can be stacked up in towers of 9 for testing, as was done for the BTEM at UCSC. He will determine the connector save length needed for those boxes and send the information to UCSC (where work needs to be done to design the MCM holding fixture).

Sandro reported on two ladders assembled at Pisa and measured. It was found that a 1-day cure isn’t sufficient with the Scotchweld adhesive, allowing deformation of the ladders if not left longer on the jig. His solution is to build more jigs, to allow a 2-day cure schedule. Gwelen noted that the manufacturer specifies at complete cure at room temperature in 7 days. Sandro reported that they have made a ladder with 4 working detectors.

Erik reported that the assembly tooling for panels is ordered and will be delivered next week. The tooling will be made of graphite. Hytec is working on sidewall attachment issues. They were thinking of an alternative concept involving inserts similar to what Sandro showed, and Erik will soon release the drawings. However, they also have continued the analysis of tolerances in the stacking. They ran a test with an aluminum plate with a 2.5 mil offset in hole locations and found no problem with putting in the screws. At 5 mils one starts to notice, and at 10 mils one starts stripping the threads. There analysis indicates up to 7 mil errors in the stackup, which can be accommodated by oversizing the holes by 5 mils. Erik noted that the side panels can be readily drilled with more than enough precision, so they would actually help pull the stack toward the ideal alignment (i.e. if there appreciable errors, they will be in the tray stackup, not in the sidewall hole pattern). The small scatter in screw misalignment could actually be beneficial toward holding the tower rigid. Hytec will study both concepts, but prefers not to use inserts in the walls if not necessary.

Tom talked about his meeting with Teledyne last week, where he worked on setting up a procurement. He also visited an aramid PC board vendor. Further discussions need to take place with our collaboration on whether we want to pursue embedding the converter in the circuit. The vendor indicated that they could do that.

Action Items:

1. Erik: release the Hytec conceptual drawing of sidewall attachment with inserts and no conical head screws.

2. Sandro: determine the length needed for connector savers and communicate the result to UCSC.