1. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 1 GLAST Large Area Telescope: Tracker Subsystem Robert Johnson Santa Cruz Institute for Particle Physics U.C. Santa Cruz Tracker Subsystem Manager johnson@scipp.ucsc.edu 831-459-2125 Gamma-ray Large Area Space Telescope

2. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 2 Outline  Overview  Schedule  Roadmap to Manufacturing  Top Issues and Risks

3. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 3 Design Overview 19 stiff composite “tray” panels support SSDs on both faces with electronics on two sides. –Converters are on the bottom face, just above the SSD plane –2-mm gap between trays 16 layers of tungsten converter foils. –12 layers of 3% X 0 converters –Followed by four 18% layers 18 x and 18 y SSD planes. Carbon-fiber sidewalls conduct heat to the base and stiffen the module. Electronics are based on 2 ASICs, PC boards, and custom flex cables. 31.6 kg mass per module. 10.5 W of power per module. Readout Cable Multi-Chip Electronics Module (MCM) 2 mm gap Carbon- Fiber Wall 19 Carbon-Fiber Tray Panels

4. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 4 Production Overview Cable Plant UCSC SSD Procurement, Testing Japan, Italy, SLAC Electronics Design, Fabrication & Test UCSC, SLAC Tracker Module Assembly and Test Italy Tray Assembly and Test Italy SSD Ladder Assembly Italy Composite Panel & Converters Engineering: SLAC, Hytec, and Italy Procurement: Italy 2592 10,368 342 648 18 Module Structure (walls, flexures, thermal-gasket, fasteners) Engineering: SLAC, Hytec Procurement: SLAC 342

5. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 5 Near-Term Schedule (  =key milestone) Engineering Model: Complete EM electronics fabrication.Nov 22, ’02 Complete EM tray panel fabrication (except bottom).Nov 25, ’02 Live EM trays ready for testing.Dec 15, ‘02 Mechanical tower trays completed (except bottom).Jan 20, ‘02 Functional mini-tower delivered to SLAC.  Jan 15, ‘02 Critical Path Bottom Tray: Critical Path Complete coupon tests and assembly of proto test tray.Dec 15, ‘02 Complete mechanical testing of proto bottom tray and tower.Jan 17, ’03 EM bottom tray fabrication completedFeb 14, ’03 Vibration test of the EM tower: Mar 3-7, ’03 Tracker subsystem Peer Review:  April 9, ‘03

6. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 6 Near Term Schedule Flight Hardware Production: Begin flight SSD ladder assembly (in progress).Nov 1, ‘02 Critical PathSubmit ASIC production.  Critical Path Dec 15, ‘02 Begin machining of tray-panel closeouts.Jan 6, ‘03 Begin assembly of tray panels.Jan 24, ‘03 Begin MCM assembly.May 12, ‘03 Begin Assembly of Qual and Spare Towers.Oct 20, ‘03 Begin Assembly of Flight Towers.Nov 17, ‘03 Deliveries to other subsystems: Functional mini-tower to I&T.Jan 15, ‘03 Mechanical tower to I&T.Apr 1, ‘03 Deliver 36 MCMs to Electronics (for EM2).July 18, ’03 Qualification and Spare Tower to I&T.Jan 20, ‘04 Flight Tower Deliveries Begin.Mar 1, ‘04

7. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 7 Tracker Production Flow SSD Production and Test 11/01-10/03 Tray Panel Fab And test 1/03-11/03 Ladder Assembly and Test 11/02-10/03 MCM Assembly Test and Burn-in 3/03-10/03 Readout Cable Fab and Assembly 2/03-10/03 Sidewall Fabrication 2/03-10/03 Tray Assembly And test 7/03-4/04 Tower Assembly 10/03-5/04 Tower Testing 11/03-8/04 ASIC Procurement, Test and Dicing 12/02-5/03 PWB Procurement and Flex Attach 1/03-3/03

8. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 8 Major Procurements ItemBeginCompletion 11,400 SSDsNovember 2001September 2003 Carbon-CarbonJune 2002March 2003 Aluminum CoresOctober 2002January 2003 Face sheets & wallsOctober 2002June 2003 ASICsDecember 2002March 2003 MCM PWB & passive components January 2003March 2003 Connectors & SaversJanuary 2003March 2003 Flex circuitsJanuary 2003June 2003 EGSE Test StandsDecember 2002April 2003

9. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 9 Progress Since Delta-PDR ASIC design and test: –GTFE design is fully functional. –GTRC is working but needs some logic corrections for flight (new logic under test in FPGAs). –3 complete MCMs (26 chips each) are under test. –Mini-MCM connected to full SSD ladder demonstrated satisfactory noise performance. –Radiation testing in progress. –GTFE wafer probing working. –MCM production testing is ready for EM production. –Prototype EGSE test stand exercised with multiple MCMs. EM MCM production: –In progress at Teledyne Electronics Technologies Flex cables –Draft spec in place. –EM cables nearly finished. SSD procurement total: –> 4600 delivered. –> 3500 tested by LAT. Ladder assembly: –EM ladders completed. –PRR held for flight ladders. –Flight ladder assembly begun at G&A Engineering (30 in test). Tray fabrication: –At least 16 EM panels fabricated at Plyform. –Satisfy dimensional tolerances. –Fixtures are ready for Kapton, tungsten, and SSD mounting.

10. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 10 Design Status: Work Still in Progress Electronics: –GTRC/GTFE ASIC designs need some small modifications to increase timing margin in data transfer between the two. Bottom Tray and Tower-Grid Interface: –Invar closeout has been investigated and is now only a backup solution. –Reinforcement of the existing design is being followed in work with COI and Hytec. Coupon testing and preparation of a prototype tray will be completed one month from now. –Hytec will be updating the tower model, completing analysis work, and preparing load and vibration tests. Tower Sidewalls: –Design in the high-conductivity material exists and is being prototyped and tested in Italy. Drawings: –79 design drawings are in Cyberdocs and on the Tracker Web drawing tree. –At least 28 are released and under configuration control. Assembly Fixtures: –Tower assembly fixture design is in progress (2 nd iteration). This work includes study of alignment of Grid mounts. –All other fixture designs are complete and in use for EM fabrication.

11. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 11 Tracker Engineering Model Full-scale mechanical-thermal tower: –19 Trays, sidewalls, flexures, etc. to the flight design. –Dummy Si detectors (including some HPK SSD rejects). –Dummy MCMs loaded with resistors to dissipate the expected electronics power load. Functional mini-tower: –4 trays loaded with 3 x-y planes of functional detectors and electronics and 3 planes of tungsten foil. –1 bottom dummy tray without electronics for a “Grid” interface. –Aluminum sidewalls. –Standard readout cables. Functional qualification tray: –Another functional tray for additional environmental testing. MCMs –8 additional functional MCMs for qualification and electronics testing.

12. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 12 Tracker EM Test Matrix Item QuantityFunctionalThermalCycleQual LevelThermalVacuumQual LevelStaticLoadSineSweepRandomVibeEMIRadiation ASICs338 MCMs13 Tray Panels 23 Accept SSDs128 Ladders32 Live Trays 5 11 Qual Dummy Trays 19 BotX5 Qual Live Mini Tower 1 Tower1 Qual

13. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 13 EGSE and MGSE EGSE MCM acceptance testing and tray-level electronics tests: –Simplified system exists and works well. –Some software development still needed to simplify use interface. –Some recoding from Python to C needed to speed up execution. –4 systems needed for production (already exist). Tower-level testing: –Standard TEM-based test stand. –In use already at SLAC with Tracker front-end electronics. –Work beginning in California & Italy to develop tower-level test scripts. –8 systems are needed for production! MCM Burn-in: –Special readout cables are in fabrication. –Control and readout will be done by the TEM-based test stand. MGSE Tower lifting fixture: –Design concept exists but detailed design not done. Tower vibration fixture –Design is complete. Tower shipping containers: –No design yet.

14. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 14 Top Issues and Risks Bottom tray and Tracker-Grid interface design –Impact: Already has delayed the Tracker Peer Review into April ’03. Further delays are possible if the present development line doesn’t work and invar (or another material) has to be used. –Issue: We need specifications for realistic input levels to use in designing the tower-Grid interface stiffness, to ensure that towers do not touch during launch. –Mitigation: Two engineering firms (COI and Hytec) are engaged in the design, analysis, and testing. A program of coupon testing is under way at COI to prove the redesigned flexure attachment joint. Mechanical testing will be carried out on a prototype (refitting of an existing tray) prior to the engineering model. –Status: Invar development on hold after preliminary magnetic measurements. Received report from Hytec on issues with invar and other materials. Coupon testing and refitting of the test tray will complete by Dec. 15.

15. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 15 Bottom Tray Reinforcement Double-Lap- Bond Ti Corner Fitting Modified Ti Side Fitting to Bond to Sandwich Panel Carbon-composite angle brackets Concept under study and test for reinforcing the bottom tray and the flexure mounts.

16. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 16 Top Issues and Risks ASIC Design and Production –Issue—some modifications are still needed for the flight run: Several logic errors remain in the latest GTRC prototype IC, even though it works sufficiently well for EM production and testing. Data transfer from GTFE to GTRC works at 2.5V and 20 MHz, but with no margin to go to lower voltage or higher frequency. About 20% of the GTFE-G are unstable at low threshold. –Impact: a failure of the production run would delay the Tracker delivery by about 4 months. –Mitigation: A new board with 2 FPGAs and 2 GTFEs is being used to verify the modified VHDL code, including our corrections of the logic errors. The timing issues are being intensively studied in simulation to be sure that we understand them. A small modification will probably be put in to correct it (otherwise VDD will have to be raised to 2.8V). The GTFE-G stability problem has been understood and the correction was tested on actual chips by FIB surgery. –Status: the December submission date is tight but can be met.

17. GLAST LAT ProjectQuarterly Review, November 12, 2002 LAT-PR-01126 17 Top Issues and Risks Overlap of Procurements and Tracker Peer Review Preparation –Issue: slippage of the Tracker Peer Review results in numerous flight Tracker procurements occurring prior to it (see page 8): SSD procurement and ladder production –These were always scheduled to occur before CDR –CDR and PRR have already been completed for these items Mechanical materials and assembly of tray panels ASIC production and other electronics parts –Impact: Several item-specific CDRs / PRRs need to be held prior to the Tracker Peer Review: –ASIC (December) –PWB, pitch-adapter flex (January) –Tray panel fabrication, face sheets, bias circuits, etc. (January) –Flex-circuit readout cables (may be able to delay this one beyond CDR) Potential manpower conflicts with EM testing and CDR preparation. –Mitigation: We need to work with management to schedule and streamline the PRRs.