Minutes of the Tracker Technical Meeting
September 4, 2002
1. Schedule status for the E.M.
2. Ladder documentation and planning for the preproduction review.
3. Status of testing the MCM/SSD interface.
4. New live MCM board for Teledyne.
1. Robert: schedule the reviews for next week.
2. Sandro: finish the writeups and EM test results for the reviews.
3. Sandro: ask Plyform if closeout cutoff waste can be retained to be shipped back to SLAC.
4. Tom: check with Teledyne about the prototype MCMs.
5. Ossie: get the ladder/MCM test fixtures machined and shipped to Pisa.
We began with a discussion of witness samples for adhesives used in ladder assembly. Tom said that we only need to check for proper curing. No strength tests are needed. The samples should be stored for future reference. Since a new syringe is used for each ladder in general, then a sample should be take for each ladder. Tom though that these could be small samples and combined in one container per lot of adhesive.
Sandro announced that they have found a cleanroom antistatic wipe that appears to be suitable for packing SSDs. The proposed wipe for packing and cleaning is TX4025 ESD Wipe by Texwipe. The declared resistivity is 60Mohm/square. The plan is to place these around the SSDs before inclosing in the cardboard. Initial tests show no particulates being deposited by the cleanroom wipes.
We discussed when to have the preproduction review. Robert sent Sandro his edit of the documentation, and Sandro is filling in the missing blanks. The EM ladders are being encapsulated now, so test results and completed documentation should be ready by the end of the week. Sandro is anxious to get G&A started so as not to be pre-empted by AMS production. We decided to hold the preliminary review of the material on Monday and the official preproduction review on Thursday. (Note---in the following LAT management meeting it was noted that Darren will still be on travel Monday, so some scheduling work is still going on.)
Sandro reported that Plyform completed the new insert bonding tool and assembled 8 closeouts. They will be checked in Pisa tomorrow. Pisa has also measured the two last trays produced (including the one with intentional defects in the facesheet bonding). They were done with the new tray assembly tool. The dimensions are under good control. The maximum error is less than 40 microns in overall dimensions, so the tray assembly tool is good.
Plyform starting machining the tooling for kapton and tungsten. Sandro wanted them to start before his vacation, but the communication got fouled up and they waited until he returned. Sandro says that it will be done in two weeks, plus one week for dimensional checks. The machining of the insert bonding tool for top/bottom closeouts is being done by SLAC. The same goes for the assembly tool for top/bottom trays. Tom predicts that they will be ready in the last week in September. Tom and Ossie will be sure to CMM them at SLAC before shipping to Pisa.
Sandro said that Ricardo is sending back unused carbon-carbon pieces for material testing. Ossie asked that they try to keep and send back cutoffs from closeout fabrication in the future. Sandro will talk to Plyform about that.
The 7 pieces for the top tray arrived at SLAC yesterday. Tom will ship them to Pisa later this week. The larger bottom pieces will come late next week, as they are going through another densification pass.
BJ had a question about the insert bonding tool: where did Pisa obtain the bearings? Sandro says to send it to Pisa without the bearings, as they can use the bearings from an old tool.
Teledyne hasn't sent the prototype MCMs yet, which are to be sent to Pisa for testing the interface with the trays. Tom will check on what is holding that up. Robert said that SLAC should test a thermal model board for correct current draw as soon as one is available with components loaded.
Tom said that Dave Nelson wants to do one functional board at Teledyne and test at SLAC before starting production of the remaining functional boards. Two bugs were found in the PWB design, so the board has to be re-run quickly.
Robert said that 4 wafers of chips arrived at UCSC this morning, so that UCSC can begin testing chips for the EM fabrication.
Ossie said that he has drawings ready for the MCM/ladder test fixture. A couple of days in the SLAC shop and they should be ready to ship to Pisa. Sandro said that he is ready to mount ladders on them.
BJ has found an off-the-shelf thermal gasket material made from BeCu. He has ordered a sample. Tom looked at the expected delta-T for similar gasket and found that it is in the needed range. He has been looking at putting a high emissivity surface on the Al foil on the outside of the Tracker tower. Probably paint is the best choice.
Erik asked if it is okay for the inner towers to be hotter than the others (since the outer ones will radiate more to the ACD). Nobody could think of a problem with that. The advantage of the radiation is that there would be only a 4 degree C increase in tower temperature of an inner tower in case that it completely loses contact to the grid. The temperature rise is much higher if the tower is silver. Erik asked why not just put the aluminum on the inside? Tom said that the main problem is connecting electrically around the tower corner in that case.
Tom said that the tower assembly fixture is not in progress. SLAC needs to start working on the drawings.
Lifting fixture drawings are fairly complete.
Sidewall machining for the EM: Ossie wants to get a quote from GMSI. The other option is to use a machine at SLAC, but it is in high demand. Erik will ship the blank panels to SLAC.