Minutes of the March 18, 2004 Tracker Meeting
- Martin: send out the bottom tray assembly drawing check prints
- Martin: send the bottom tray closeout drawings out for release
- Riccardo: check Plyform drawings against the latest releases for mid-tray production
- Jeff: update the COI PO to get the bottom tray closeouts machined
- Martin: send Sandro known constraints on the MCM mounting pin head
- John Ku and Mike Opie: draft or redlined static and vibe test plans
- Thermal-vacuum test update
- Contact needed in Italy for Jeff Tice regarding database of tracker parts and materials
- Maximum sidewall panel thickness
- Control of drawings for tray production in progress; what to do with drawing-checker comments
- Assembly procedures and PRR for bottom/top tray panel production
- Bottom tray status:
* closeout and assembly drawings
* closeout machining
* assembly tooling
* static test system & visits to Italy
- Status of MCM integration testing at G&A
- Bias circuit status
- MCM production status
- Flex-circuit cable status
Nicola reported that the thermal/vacuum data analysis is in progress and first results will be reported at the meeting next week. See the Bari website for thermocouple data.
Work is going on in Pisa to understand the problems seen during the test with fluctuations in power, but they have not been able to reproduce the problem so far.
Robert clarified that the “dummy TEM” used in the test resembled a real TEM only in the shape of the aluminum box. The resistor divider circuits for reading the thermistors was copied from the actual TEM schematic, but all the power distribution was ad hoc. The real TEM has a power supply sitting on its back, whereas the current for the dummy was supplied through long wires from an external power supply. Dave Nelson reported that they tested the thermistor readout in a real TEM at SLAC, connected to 36 real MCMs, and the thermistor readout did not change when the MCM power was turned on and off.
Nanda confirmed that Pisa received the 10 preproduction MCMs from SLAC, with 2 burn-in cables, but they have not yet tested them.
Jerry reported that 50 bias circuits should be arriving at SLAC today from Parlex in San Jose. SLAC will CMM 2 of them. They should ship to Pisa today or tomorrow.
Jerry is trying to get the PO placed for the 1/4-oz circuits. Probably they will be received at SLAC 3 weeks after the PO is in place.
Parlex will then ship 50 per week until done.
Darren wants us to hold an MRB on the issue of trace extensions for plating.
Sandro said that the contact person in Italy for Jeff Tice, for accounting of parts and materials, is Mirco Bagni.
Sandro reported that the maximum sidewall thickness measured on the EM panels was 1.57mm, including the 50-micron aluminum. Sandro will send the detailed data. Robert said that for the COI test coupons the maximum was about 1.60mm. Ben Rodini has specified a maximum of 1.63mm in the procurement document.
Sandro reported that G&A is producing the tools for the MCM mounting tests. G&A made the first measurements on the 7 MCM boards yesterday. Sandro will send the results to SLAC after G&A rechecks the locations of the mounting holes, which looked in error. The LAT drawings change only in the mounting pin. Tray mockups for this test will be ready in 2 weeks. In 3 weeks the first tools for MCM mounting will be ready. It will allow horizontal adjustment such that any pitch error can be split from the center. Sandro predicted that G&A will be ready for production at the end of April.
Martin reported that the bottom tray assembly drawing check prints will be available tomorrow or Saturday. Riccardo is waiting on them in order to verify the bottom tray assembly tooling design.
Martin also said that the bottom tray closeout drawings will go out for approval today (this got delayed a little later in the day by some redlines that came in from COI).
He also pointed out that we need to change the insert epoxy callout for the mid tray closeout assembly drawings. It should be Hysol 934NA, which is what Plyform is actually using.
Martin noted that all drawings released from now on for flight-article fabrication will be stamped “Released for Flight”. This is not the case, however, for drawings already released, for the mid trays, for example.
Regarding the mid-tray drawings, Riccardo is going through the drawings used by Plyform so far in mid tray production and checking them against the latest releases. For example, Plyform machined some inserts and closeouts last September (using drawings transmitted by SLAC that were released at that time---most of the mid tray drawings were released at CDR time). The reader may recall when flight tray panel fabrication was supposed to begin in September 2003. There should be no dimensional changes made to the mid-tray parts since then, but some notes may have been added to the drawings. Riccardo will then transmit the latest releases to Plyform. He will also look for any redlines made by Plyform to these drawings, or any inconsistencies between the drawings and the actual Plyform procedure, and will transmit this information back to SLAC for the corrections to be made.
Sandro asked for a schedule on the bottom tray closeouts. Jim said that Jeff Tice will work the COI PO. Robert said that it needs 2 line items added to it for machining of the closeout parts. This machining needs to get started next week, but first the drawings need to be released, the PO needs to get to COI, and Martin needs to talk through the drawings with Toan Pham at COI. COI will deliver the first 2 sets of closeouts in 2 weeks ARO.
It was noted that the bottom tray insert designed changed, so Plyform will have to remake the bottom tray inserts.
There was a question on the sidewall insert status. Robert believed that SLAC had manufactured all of them for the flight build, but Martin is seriously considering reducing the thickness, in which case they need to be re-ordered. This is a SLAC responsibility.
Martin needs information on the pin for MCM mounting, to make sure there are no conflicts. Martin will send Sandro his known constraints.
We discussed a schedule for Erik Swensen and John Ku to travel to Pisa to help with the static test setup. They should arrive on March 31. At that time they also need to discuss static testing and vibration testing in general. SLAC needs to produce a static test plan of reduced scope, and also a vibe test plan. John Ku and Mike Opie are responsible. They need a draft or redlines of the current drafts before going on the trip.
Mike Menning explained that they have been going through tolerances in detail, including clearances, machining tolerances, Grid contributions, thermal movement, dynamic motion, etc. They find that there is lots of difficultly making the concept of 3 concentric cones work. An alternate plan has been identified that involves the use of eccentric cones everywhere. This will cause lots of pain on both sides of the Atlantic. Mike will prepare charts for an 8:00 am Monday telecom.
Action Items from Last Week:
1. Jerry: submit an NCR on the extended traces for plating the 50 bias circuits (in work)
2. Darren: notify the software development team of the implications of the bias circuit NCR (done)
3. Robert: write a statement on the science impact of the heavier copper
4. Sandro: respond to Robert and Jerry on the options presented for avoiding trimming through bias circuit traces (done)
5. Jim: find a designer to revise the static test and vibe test tooling for the new interface (April 1?)
6. Riccardo: give Robert a breakdown on the 20 trays expected March 29 (discussed with Sandro yesterday)
7. Riccardo: send a sketch of the thermal strap concept to Mike Menning (done)
8. Martin: send check prints on the bottom tray assembly and closeout assembly to Riccardo (next day)
9. Riccardo: send Martin information on the grounding tube diameter and tolerance and adhesive to Martin (done)
10.Riccardo: resolve the TBDs (best guesses at least) in LAT-TD-01918 and send to Robert for release (in progress)
11.Robert: send Mike Menning a schedule need date for the revised static test fixture (done)
12.Jim: contact Erik Swensen regarding his possible availability for travel to Italy (done)