1. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 1 GLAST Large Area Telescope: Tracker Subsystem WBS 4.1.4 Highlights in Progress Since the January Review Robert Johnson Santa Cruz Institute for Particle Physics University of California at Santa Cruz Tracker Subsystem Manager johnson@scipp.ucsc.edu Gamma-ray Large Area Space Telescope

2. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 2 Outline Overview Results from January Review Action Item Status Changes Since January Review Hardware update since January Schedule and Cost Summary

3. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 3 Tracker Overview 16 layers of tungsten converter foils. –12 layers of 3% X 0 converters –Followed by four 18% layers x-y Si-strip detector pair closely following each converter foil. Two additional pairs at the bottom are needed for triggering. 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 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 ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 4 Tracker 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 ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 5 Results from January PDR/Baseline Review The Tracker has an Experienced Project Team. The concept of the Tracker is well matched to the science goals and utilizes mature technology. The design is well thought out and can be implemented within the available time. A strong consortium of groups in Italy has taken the responsibility for assembling and testing all the ladders, trays, and towers. This is a crucial contribution to the Tracker which is being executed in a very effective and competent manner. “Baseline the Tracker with Increased Contingency”

6. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 6 Action Item Status Action ItemResponse 1Baseline the Tracker with Increased Contingency The current basis for estimating Project contingency needed uses 25% of the Tracker cost to go VS 18% in January 2Thoroughly evaluate pre-production IC’s Agreed – Plan in place 3Refine Assembly and Test Procedures Agreed – In process

7. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 7 Changes Since January 02 Review The schedule has been revised to accommodate the overall LAT schedule extension. –Added time for additional ASIC submissions. –Incorporated a more conservative schedule for Tracker module production with the Italian groups. –Critical Deliveries: Modules 3, 4 available March 29, 2004, with 11 weeks of float. Modules 15, 16 available August 4, 2004, with 7 weeks of float. Budget –Estimated cost at completion increased $180K MOA with Italy –INFN ready to sign and has been providing the requested funding and covering for the delay in ASI approval. –ASI has not yet signed but has recently begun funding Tracker work with approval of $800k for FY2002.

8. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 8 Prototype Tower Module Mechanical prototype loaded with dummy SSDs. Includes flexure interface to the Grid. Used to test and evaluate assembly methods. –Assembly worked well, but tray tolerances were not quite to specification. Tray assembly tooling has since been revised and specifications met. Vibration and Thermal testing: –Single panel: LAT-TD-759. –Grid-to-tower interface thermal cycle: report in progress. –Random vibration of the full module: LAT-TD-788. Problems (see following) Composite trays and mass models of the prototype tower, before mounting of the sidewalls.

9. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 9 Vibration Test Problem #1 Some screws attaching the sidewalls to the bottom tray backed out during transverse-axis qualification-level random vibration. This problem was solved (as verified in a retest): –Replace hex heads by Torx-Plus to enable tightening to the full specification without stripping the heads. –Double the number of screws in the non-MCM sides of the bottom tray. –Add aluminum washer-inserts to the sidewalls for these fasteners. We also plan to use a secondary locking mechanism for the screws in the final assembly, as extra insurance. Full module instrumented for thrust-axis vibration

10. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 10 Vibration Test Problem #2 In the first test, a hairline crack formed in the bottom-tray closeout between the edge and a corner-flexure fastener. In the second test suite at transverse-axis qualification levels the cracking increased and the problem propagated to all 4 corners, breaking loose the corner-flexure mount inserts. (The mid-span flexures all held fast.) Remediation in process: –Analysis to make sure we understand the failure and the cure. –Remove light-weighting cutouts in the bottom tray and increase its height by 5 mm. –Reinforce each corner with a bonded metal bracket. –Remediation Plan presented to Project ART. Cracking as seen after the second test suite.

11. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 11 Tracker ASICs The second run of the GTRC and GTFE ASICs needed to be resubmitted: –GTRC V2: Missing rule in the Tanner DRC led to a short in the memory. Although complete chip was simulated with Synopsys Timemill, clock skew margins were not sufficient for the IC to function at nominal supply voltage (Tanner does not extract the clock network as a distributed RC network). –GTFE Vf: a minor modification was not verified by simulation due to misunderstanding, missing an error that removed the baseline restoration. –GTFE Ve: the same missing DRC rule led to a nonfunctional analog chain. Remediation: –Careful crosscheck of the DRC rule-set against the Agilent vendor rules and use of the MOSIS DRC checking service. –Improved pre-submission procedural control. –Controlled row-wise clock routing in the GTRC core. –Submission of a back-up GTRC version without RAM.

12. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 12 Tracker ASICs The digital section does function in the GTFE Ve & Vf chips, allowing substantial testing to proceed: –Probe-card testing of the GTFE using the full set of test vectors developed according to LAT-TD-247. –Testing on the mini-MCM using GTRC V1 chips. Several problems were addressed in the versions in production: –Proper response in the GTFE to undefined op-codes. –Logic errors in GTFE register loading. –Protection resistors in the I/O pads led to unreliable operation at the full 20 MHz. –Clock skew issues in the GTRC. –DRC errors and the GTFE Vf comparator bug. Chips presently in fabrication (Due August 22): –GTRC with custom RAM and GTRC with Flip-Flop RAM (both usable for flight). –AC and DC coupled GTFE versions.

13. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 13 Electronics Testing Several “mini-MCMs” are under test at UCSC and SLAC, using the V1 GTRC and Vf GTFE chips. –Using COM card, interface board, and Python script at UCSC, to develop the test station for MCM production. –Using 2 COM cards, TEM, and SCL script at SLAC to debug the ultimate readout scheme. Mini-MCM has been interfaced with flight like Tower Electronics Module(TEM) to verify functionality and interfaces. Continued use for hardware and flight software development. Parts qualification is in progress for poly-switches and HV caps. Planning is in progress for radiation testing (total dose and FEE) after the new chips arrive. A mini-MCM loaded with 2 prototype front-end chips and 1 controller chip.

14. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 14 Electronics Test Systems GTFE wafer probing: –Operational on a manual probe station (undiced wafers will be available end of August). –Thorough set of test vectors for complete functional testing (see LAT-TD-247). –All of the test vectors have been exercised through the simulation and actual chips (which uncovered the bugs fixed in the present submission). GTRC wafer probing: –Complete hardware and software for manual testing. –Thorough set of test vectors (see LAT-TD-248). –No bare die yet to test it on (probes don’t fit V1). –Test vectors are presently being exercised through the simulation and on the mini-MCM (with some restrictions, such as not being able on the mini-MCM to cycle through the address space).

15. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 15 Electronics Test Systems MCM testing during production at Teledyne: –Second-version interface board is in hand with enclosure plus a better monitoring interface for power supplies and LVDS bias levels. –Test plan documented in LAT-TD-153 and LAT-TD-249. –Test vectors are under development for functional testing, based on extending the GTRC set. –VME ADC modules were obtained, and software is in progress to test the power supply voltages and the LVDS driver bias levels. –Some software has been developed for threshold scanning (analog performance tests) and tested on the d-version chip. –Basic system, to be operated by its developers, will be ready for testing the engineering-model MCMs in September. MCM burn-in station: layout of special cables is in progress.

16. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 16 Electronics Production Teledyne has successfully developed and tested the tooling for bonding the pitch adapter flex circuit onto the MCM PWB. All parts and materials are present at Teledyne to begin assembly of the dummy MCMs for the mechanical/thermal engineering model tracker module. These modules will have all parts, but with dummy or bad (GTFE Ve) ICs and with some capacitors replaced with resistors to mimic the IC heat load. All of the molded plastic MCM carrying cases are in hand (in fact, in sufficient numbers for the flight build). These are used for MCM testing and burn-in following assembly, as well as for storage and transport. Assembly of the dummy MCMs is beginning at Teledyne. Pisa is testing the MCM-tray interface, especially with thermal cycling.

17. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 17 Engineering Model Tooling & Production Experience with the prototype Tracker module led to many detailed changes in the assembly tooling designs for trays. Plyform (Italy) is now assembling EM composite panels with the new tooling, and work is beginning to add the converters and bias circuits. G&A Engineering (Italy) has assembled all of the dummy SSD ladders and is now working on the live ones, expected completion July 30, 2002. The electronics test system for the ladders is operational. Tools for mounting the ladders and for assembly of the top/bottom trays are in progress.

18. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 18 Procurement of Long-Lead Items Silicon procurement and deliveries on schedule. –2314 HPK SSDs have been received and tested in Italy. –Production of flight SSD ladders will begin as early as August 5, 2002 pending ladder assembly procedure review and release. The carbon-carbon closeout material is on order from Alcomp (US). In purchasing some items for the EM sufficient quantities for the flight build were ordered to reduce costs: –The molded MCM carrying cases. –All of the screws for sidewall attachment.

19. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 19 Summary Schedule

20. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 20 Key Milestones

21. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 21 Cost & Commitments

22. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 22 Cost Profile

23. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 23 Workforce Plan

24. GLAST LAT ProjectDOE/NASA Delta Baseline/Preliminary Design Review, July 30, 2002 Tracker, WBS 4.1.4 24 Summary The flexure-mount redesign effort is on schedule and should not delay the Engineering Model schedule or the CDR. All other aspects of the Tracker design are complete. All lowest-level drawings are in place as drafts, with 22 released. Good progress on assembly and tooling drawings. See the drawing tree on the Tracker web page. Some details of the production fixtures and processes are still being tweaked and tested as the Engineering-Model build progresses. Work is accelerating on documentation of test plans and processes and production processes, in preparation for CDR. Overall, the Tracker development is progressing on schedule for the subsystem CDR in January 2003 and the LAT CDR in April 2003.