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GLAST Large Area Telescope: Tracker, W.B.S 4.1.4 Face-To-Face June Meeting Robert Johnson

Gamma-ray Large Area Space Telescope. GLAST Large Area Telescope: Tracker, W.B.S 4.1.4 Face-To-Face June Meeting Robert Johnson U.C. Santa Cruz rjohnson@scipp.ucsc.edu. Tower Status. Towers A, B, 1, 2, 3, 4, 5: Handed off to I&T Tower 6:

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GLAST Large Area Telescope: Tracker, W.B.S 4.1.4 Face-To-Face June Meeting Robert Johnson

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  1. Gamma-ray Large Area Space Telescope GLAST Large Area Telescope: Tracker, W.B.S 4.1.4 Face-To-Face June Meeting Robert Johnson U.C. Santa Cruz rjohnson@scipp.ucsc.edu

  2. Tower Status • Towers A, B, 1, 2, 3, 4, 5: • Handed off to I&T • Tower 6: • Assembled and electrically tested with C5, C6, and C7 cables missing. • Sidewalls installed and full alignment CMM measurements done. • Stored in its inner shipping container in the Pisa cleanroom. • Tower 7: • Assembly is in progress in Pisa. • Only 2 cables (C0 and C1) are available in Pisa for this assembly. • Tower 8: • All but 3 (heavy) mechanical panels were delivered by Plyform as of Monday of this week. The remainder should be delivered this week. • G&A is assembling Tower-8 trays. • Tower 9: • At least most of the Tower-9 mechanical panels should be delivered by the end of this week.

  3. Tray Panel Fabrication • Plyform received a payment on their first invoice under the ASI/G&A subcontract, which helped defuse many concerns. • Plyform has been doing an excellent job at delivering trays. • There have been some potential material problems: • Defective bias circuits (see the following slide). Replacements are on order. • Carbon-carbon materials: the last orders were received and shipped to Italy. • Tungsten tiles could hold up the show. • The new orders were received in Italy and shipped to GSFC. • Substantial customs delays resulted. • Pisa has said that delays could result if the tiles are not receive in Italy by about June 20 (next week). • The work is now in progress at GSFC, but I don’t yet have a status update on when the first batches will be ready.

  4. Bias Circuit Issue • The root cause of the bad circuits was never determined. • The bad circuits have a different color in the region where there is no copper plane. See below. • However, a visual screening procedure was discovered, and we found that a total of 75 circuits have to be replaced. This region delaminates easily in the bad circuits. FAILED PASSED

  5. MCM Production • Production halted for one week to rework the tooling for flex trimming. • Production is underway again this week. 15 MIP-2 tests Mon./Tues. • Only about 2 more weeks of production are needed for flight towers.

  6. MCM Production Issues • We believe that we have resolved the financial issues remaining in the contract with a good compromise between SLAC and Teledyne (many thanks to Ladan Saghafi in SLAC purchasing!). • Omnetics connector deliveries are critical for keeping the Teledyne production rolling. • The next delivery date given by Omnetics, July 1 for 400 units, is most likely too late to avoid a work stoppage at Teledyne. • Jeff Tice is pushing Omnetics to deliver some connectors earlier than that, but they have been strongly resisting so far. • We have started removing connectors from failed flight MCMs in order to build up a stock of usable connectors, just in case. They are now in the hands of QA for cleaning and inspection. • The first production trial of conformal coating (4 MCMs) had problems that have not yet been resolved. Production is continuing with the in-house Teledyne process. Moving to the new process becomes less and less attractive as we near the finish line.

  7. Flex-Circuit Cables • The last Tower-6 cable is supposed to ship from Parlex June 24 • I’m hoping to get some firm information on Tower-7 cables from Parlex today. In principle they are only slightly behind Tower 6. • Cables are dribbling in from Parlex, with 4 shipped last week and hopefully at least 3 this week. • Parlex was funded to make 2 improvements: • Work weekends • Retool the longest cables to go 4 per panel (not diagonal) on a new panel size that Parlex is now processing (this will not pay off immediately) • We are investigating relaxing the annular ring requirements to IPC Class-3 specs to improve the yield. • Pioneer flex-circuit manufacturing is in progress, with all circuits due to be fabricated by July 1. • Pioneer is also actively working on assembly issues, including making test assemblies.

  8. Tracker Tower RFI Schedule These are my guesses, based on my MS Project schedule. Towers 6 and 7 are already in trouble due to lack of cables. INFN believes that up through Tower 14 can still be assembled and tested in Italy by end of August if cable sets start arriving regularly no later than mid July (assuming that at least Towers 6 and 7 are equipped and tested earlier). There are potential problems with competing for access to the Alenia vibration facilities.

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