Minutes of the Tracker Meeting
October 30, 2003
New Action Items:
Old Action Items:
Organization of a follow-up PRR for mid-trays:
††††† Sandro reported that the new procedure document is nearly ready.† It just needs a drawing showing masking of paint and conductive glue.† We decided to hold the PRR Monday November 10.† Nanda will make up an Agenda.† Tom will set up a telephone conference for 8:15am.
Documentation for bottom-tray closeouts:
††† † Tom will work this with BJ; he has talked to Jerry.† COI will not start assembly and machining until these are released.
PRR for bottom trays:
††††† Pisa is still working on drawings of tools for bottom tray assembly.† The tools must accommodate assembly with flexures attached.† Tom will ask the machine shop making the flexures and corner brackets to assemble them together and check the fit.† For this we will need to make an assembly drawing.† Tom said he will work to estimate delivery times for titanium parts and bottom-tray closeouts.
Thermal blanket specs for T/V test; status of T/V test preparations and documentation:
Sandro sent our drawings to Alenia.† The tower sits between two bars, with the TEM below level of bars.† See the attached jpeg files.† The tower will move with the front wall, so there will be no movement of cables.† We need to add details to the drawings to interface with rails.† Sandro suggested a thermal strap from the dummy TEM to the adapter plate and also a blanket around the TEM.† Tom said that he talked to Jack about this.† He suggested putting a heater on one side of TEM.† The TEM will be on a plate mounted with standoffs below the Tracker, wrapped in a thermal blanket.† We want to understand heat flow through the cables into the TEM.† Jeff will run a simple model to estimate how much heat will flow through the cables.† There were conflicting statements on whether Alenia can readily support a separate heater circuit for the TEM. †Nanda thinks it would be no problem.
Sandro said that he plans to arrive at Alenia with the adapter plate and TEM mounted.† Nanda prefers to mount it all when inside the chamber.† A crane is available over the chamber.† Action: Sandro will write down a plan for this, and we will arrange a telecon soon with all thermal engineers late next week Thursday or Friday.
1. SLAC (Jack, Jeff, Tom) will generate a talking paper on thermocouple locations, thermal blanket requirements, TEM temperature control and definitions of test cases and dwell times.†
2. Italy will update the plan and procedure accordingly.†
Tom said that we don't need a long dwell time because there are no electronics.† Sandro needs this information soon, by Tuesday.† The TRR should be held the week of November 24.† The plan and procedure must then be released for review the week before the vibration test.
The TRR will be held next Tuesday.† Tom said that we can expect some simplifications of the vibration requirements.† Some of the sine vibrations at low frequency donít make sense for a tower that acts like a solid brick below 50 Hz.†
Status of EM sidewall fabrication:
There are some delays in COI mini sidewalls because of the San Diego fires.† Erik said that we need a new plan laid out, because Hytec test time is getting cut short.† Tom will work that today.
Sandro reported that Plyform has done some tests and is going to start laminating sidewalls tomorrow.† To avoid bending from CTE mismatch they decided to post bond the aluminum at room temperature using the 3M 2216 epoxy.† Tom and others objected to this change, as the drawings and specifications are already released.† We decided that the sidewalls need only be flat with some restraint, and Sandro said that a very small force was sufficient to pull them flat.† We resolved to co-cure the aluminum as specified on the drawings.† Tom will update the drawing note to make the flatness requirement clear.
††††† Coupons will be available just after the sidewall layup.† Sandro will ask for a precise completion date for the coupons tests.
††††† Tom will send COI coupon test data to Italy for reference.
Report from yesterday's meeting on tower test script preparation:
††††† See Luca's minutes posted at http://glastserver.pi.infn.it/glast/glastDAQ/html/minutes.html. †Luca said that there are problems getting the old Motorola VME processors.† He needs a reply from Gunther.† Tom will talk to Gunther.† Luca questioned the decision to stay with the outmoded units and volunteered to help port the software to new processors.† Luca will check again on how many of the old ones are available in Italy, but he already knows that he cannot obtain the quantity needed.†
GTRC and MCM production status:
††††† The new GTRC design (V7) has been completed and verified, including tests of the logic code in FPGAs and tests of the timing fix in Accurel FIB (focused-ion-beam) modified V6 chips.† The submission is waiting on the purchase order.† Two versions will be submitted: the V7 version with TOT and timing repaired, which involves replacing the logic core with a new auto layout, and a V6b version which is just hand edited to fix the timing problem (nearly identical to the FIB modification). †A TEM ASIC cable controller chip with TOT incorporated may also be submitted, if it fits in the reticle.† This logic has been tested in the FPGA in the mini-tower and works.
††††† The MCM preproduction is starting.† 6 MCMs will go ahead as pathfinders in each process step, and we will monitor the quality of those boards after each step.† After the flex-attach step SLAC will CMM the wire-bonding edge of the board to check flatness and uniformity.
Flex-attach fixture development at G&A:
††††† Sandro was at G&A yesterday discussing development of a new flex-attach fixture to replace the Teledyne tool.† They found issues with the dimensions of the actual parts versus the drawing.† Robert said that the drawing makes assumptions about glue thickness that are not correct.† The 75-micron glue line between the PWB and raised strip is probably less than 25 microns.† The total thickness shown in the drawings is for reference only and is not a requirement.† The actual boards are the best reference, since they are from the flight-production lot.† Sandro also said that the boards do not lie flat.† Robert replied that this is expected, due to asymmetry in the stackup and the long-thin geometry. †Only a small force is needed to pull them flat, so they have to be worked with under restraint.