Minutes of the Tracker Technical Meeting
May 17, 2001
Ossie was not able to attend the meeting, but Robert summarized his email about tungsten:
“I did make a lot of inquiries about tungsten. It seems like the best way to handle the thick material would be to buy double disc ground wafers. I have a quote for ~$41 with a TEN week lead time. Tungsten in thin form is dearly scarce right now, with up to 36 weeks being quoted by some suppliers. I found out that they do not roll tungsten alloys in this thickness range because the material tends to segregate. So none of the copper/iron/nickel compounds would be applicable to our needs. All of these compounds are sintered powdered metal products, pressed to near net size with minor additional finishing to avoid provoking segregation. The ground material promises a plus or minus 0.0005" tolerance, so in terms of Z it’s even better than the thin material that we obtained from CSM.”
Sandro said that he ordered a 0.3mm +-35um (1 m by 20 cm, to cut into 22 pieces) foil to glue together to make thick converters. He expects delivery by the end of July. He plans to continue with the existing foils for the mockups that he is presently working on.
Tom agreed to order immediately a small quantity of the ground tungsten that Ossie mentioned (at least enough for a full tray).
Robert talked a bit about PDR preparations. The date now is firm: June 19. The documentation package needs to be complete, to be sent to reviewers, two weeks in advance. Hartmut said that the PDR organizer, David Lung, wants to meet with Robert and Tom next week.
Robert reported that Hytec ordered aluminum cores a few days ago, for a 4 week delivery. They ordered enough for Sandro’s work and for the engineering model. It will be already expanded and cut to size. They ordered some of all 3 types (normal trays, top and bottom trays, and heavy trays).
Hytec had their existing Allcomp material sliced into closeout-size strips and re-impregnated with resin. They found that re-impregnating already machined parts was not a good idea, as the machine tolerances get severely messed up. They tested the strength of the material before the re-impregnation. The tensile strength was good and equivalent to what they saw in the past with the treated airline brake material. That was expected, since the tensile strength comes from the fibers. The present material, however, was somewhat more flexible, due to the lower densification.
Hytec is working on getting new quote from COI for the tower sidewalls.
Sandro reported that they have done tests on positioning of glue spots for silicon attachment. They got good results with their robotic dispenser. GMA has done some wire bonding tests. They found that they can make 0.2 mm high bonds with good strength (7 g). Mipot has made its first encapsulation trials on wire bonds on a test setup, which puts all of the bonds in series to facilitate electrical continuity tests. They are still using a manual procedure and cannot control the thickness. They did find that the potting does not interrupt the chain of bonds (the electrical continuity is not disrupted). They will do thermal tests as well. Pisa has defined drawings for the next set of mockups. Drawings of the closeouts walls are on the web. They decided to move references from the middle axis so as not to interfere with the alignment holes of the Hytec prototypes. Sandro received quotations on inserts. Aluminum ones are about $1.50 each. Titanium is only about 25% more. Sandro suggested aluminum screws, which would be interesting from a mass and radiation length standpoint. Strength testing would have to be done in that case. Sandro prefers titanium for the inserts, just to be absolutely sure that threads in completed trays do not get damaged. They also received Quotations for probe stations. They are in the cost range expected. They are looking at standard 6-inch wafer probing stations, which can be adapted to probe ladders.
Robert agreed to send the new pitch-adapter drawing to Sandro, to be used to make prototypes at CERN. It differs from the previous version already prototyped at Qflex in that the cover layer is tied to the surrounding Kapton between each pair of chips, to keep the cover layer aligned during fabrication.
Tom said that he has not heard from companies on quotes for the MCM and the cable.
Harmut reported that HPK made the 1st 100 detectors, only 1 week late. Ohsugi will start doing monitoring of cutoffs and also check the data from HPK. He will put the results on the web. A P.O. is working its way through SLAC for the flight-production order. It is urgent to get customs issues worked out. Ronaldo needs to arrange this on the Italian side. A QA document is being finalized with Nick Virmani. Sandro said that he will keep detectors in an N2 box in Pisa until the commercial firms are ready for them. Hartmut said that HPK will not ship until Pisa is ready to use the detectors. Sandro said that ladder production will be starting in September or October. Harmut would like Sandro to write down their testing and storage plans. Sandro said that he will put it onto the Pisa web page.
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