1. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 1 Silicon-Strip Tracker Converter Robert P. Johnson Santa Cruz Institute for Particle Physics University of California at Santa Cruz Tracker Subsystem Manager johnson@scipp.ucsc.edu

2. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 2 LAT Tracker Subsystem  LAT design overview  Tracker technical challenges  Derived Tracker requirements  Tracker technical description Mechanical design and prototyping Silicon-Strip detectors Electronics design and prototyping  Tracker organization and WBS  Tracker assembly  Tracker status  Tracker schedule and milestones  Tracker budget  Tracker issues  Conclusions Outline

3. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 3 LAT Design Overview 16 towers  modularity height/width = 0.4  large field-of-view Si-strip detectors: 228  m strip pitch 18 x,y measurement pairs 12 layers of 3% X 0 converters 4 layers of 18% X 0 converters 8.8  10 5 readout channels Carbon-fiber composite structure Instrument Tracker Calorimeter Anticoincidence Detector Shield

4. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 4 Tracker Technical Challenges Detector system: achieve nearly 100% efficiency for MIPs in the detector active volume, with 60 micron spatial resolution. –Silicon-strip detectors readily meet these requirements. Electronics: operate nearly a million channels on <300 W while maintaining sufficiently low noise for the Tracker to self trigger and while handling a high readout rate with negligible dead time. –Specialized ASICs have been under development for 5 years and have demonstrated these capabilities in beam tests. Mechanical structure: maintain high transparency to charged particles while supporting detectors and electronics during launch. –A mechanical structure based on honeycomb panels and carbon- fiber composite materials is under development. Modular design: minimize dead space within the tracking volume. –Miniaturized electronics mounted on the edges of the panels. Reliability: eliminate susceptibility to single-point failures. –Two independent readout paths for every channel. Assembly: large number of repetitive parts to assemble. –Use industrial assembly techniques for electronics packaging.

5. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 5 Derived Tracker Requirements The following table is a summary of some of the requirements from the Tracker Level-3 Requirements Document. These requirements derive from the LAT Performance Specifications.

6. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 6 Tracker Technical Description 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 + 2 additional pairs at the bottom. 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 –Trays stack and align with pins in the four corner posts Carbon-fiber sidewalls conduct heat to the base and stiffen the tower. Electronics are based on 2 ASICs, PC boards, and custom flex cables. 30.5 kg mass per tower Readout Cable Electronics Module 2 mm gap Carbon- Fiber Wall 19 Carbon-Fiber Tray Panels

7. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 7 Tray Mechanical Design Early SBIR prototype all- carbon tray Closeout assembled from four machined carbon- carbon parts Carbon-Fiber Face Sheet Aluminum Honeycomb Core f 0 of completed assembly (with SSDs and converters) > 500 Hz. Engineering and development by Hytec, Inc., Los Alamos –Machined carbon-carbon closeouts, with metal inserts for fasteners –Carbon-fiber face sheets, 4 or 6 ply –Aluminum hexcel cores –Parylene or metal passivation of carbon surfaces –Precision assembly fixtures Flight-panel fabrication in Italian Industry

8. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 8 Silicon-Strip Detectors Principal vendor, Hamamatsu Photonics, is already qualified, with prototypes of the final design delivered and exceeding specifications. Hamamatsu’s production capacity can satisfy all of GLAST’s needs. Procurement is beginning NOW; ramping up to >500 sensors per month. AC-coupled, with polysilicon bias resistors 8.95 cm square (6” wafers) 400 microns thick 384 strips 228 micron strip pitch 64 micron strip width Depletion < 150 V Leakage current <800 nA (avg. <240 nA) per sensor Bad channel rate <0.2%

9. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 9 Tracker Electronics Low power (210 W for 884,736 channels); low noise (<10  5 occupancy). Redundancy: 2 readout paths for every channel. Low dead time: 20 MHz readout; event buffering at the front end. Compact: readout module fits in a 4.2 mm gap along the tray edge. Block diagram of the data and control-signal flow for the Tracker readout system. A full-scale, fully- functional prototype system was built for the BTEM.

10. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 10 Tracker Electronics The prototype electronics functioned well in the beam test, but the design is being updated to –reduce interference from clock transients –match the new tray size and SSD pitch –satisfy new T&DF requirements –follow all IPC and other relevant design rules –use space-qualified parts –facilitate assembly and integration BTEM Tracker

11. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 11 Tracker Organization System Engineering Quality Assurance Resources, Reporting System Engineering Quality Assurance Resources, Reporting GLAST Tracker Subsystem Manager R. Johnson UCSC GLAST Tracker Subsystem Manager R. Johnson UCSC Mechanical, Thermal System Engineer T. Borden SLAC Mechanical, Thermal System Engineer T. Borden SLAC SSD Design, Testing, Procurement T. Ohsugi, Hiroshima U. SSD Design, Testing, Procurement T. Ohsugi, Hiroshima U. Italian Tracker Project Manager R. Bellazzini, INFN-Pisa Italian Tracker Project Manager R. Bellazzini, INFN-Pisa INFN Tracker Development Engineer A. Brez, INFN-Pisa INFN Tracker Development Engineer A. Brez, INFN-Pisa Mechanical Engineering Design E. Swensen, Hytec Inc. Mechanical Engineering Design E. Swensen, Hytec Inc. Electronics Mechanical Assembly & Integration G. Paliaga, UCSC Electronics Mechanical Assembly & Integration G. Paliaga, UCSC I & T Supervision O. Millican, SLAC I & T Supervision O. Millican, SLAC Tracker Electronics Lead Engineer D. Nelson, SLAC Tracker Electronics Lead Engineer D. Nelson, SLAC Tracker Power Supplies & Housekeeping D. Nelson, SLAC Tracker Power Supplies & Housekeeping D. Nelson, SLAC Ladder, Tray, Tower Production Supervisor A. Brez, INFN-Pisa Ladder, Tray, Tower Production Supervisor A. Brez, INFN-Pisa Electrical Interconnects D. Nelson, SLAC Electrical Interconnects D. Nelson, SLAC Electronics System Testing W. Kroeger, UCSC Electronics System Testing W. Kroeger, UCSC Front-End ASIC Design E. Spencer, UCSC Front-End ASIC Design E. Spencer, UCSC Readout Controller ASIC Design J. Olson, SLAC Readout Controller ASIC Design J. Olson, SLAC Tracker Scientist Performance H. Sadrozinski, UCSC Tracker Scientist Performance H. Sadrozinski, UCSC

12. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 12 Tracker WBS Organization GLAST LAT IPO Stanford GLAST LAT IPO Stanford LAT Tracker Subsystem WBS 4.1.4 Italy, Japan, SLAC, UCSC LAT Tracker Subsystem WBS 4.1.4 Italy, Japan, SLAC, UCSC Tracker Management WBS 4.1.4.1 Subsystem Mgr: R. Johnson, UCSC Italian Mgr: R. Bellazzini, Pisa Syst. Eng.: T. Borden, D. Nelson, SLAC Tracker Management WBS 4.1.4.1 Subsystem Mgr: R. Johnson, UCSC Italian Mgr: R. Bellazzini, Pisa Syst. Eng.: T. Borden, D. Nelson, SLAC Reliability and QA WBS 4.1.4.2 T. Borden, SLAC Reliability and QA WBS 4.1.4.2 T. Borden, SLAC Tray Subassembly WBS 4.1.4.3 Tray Subassembly WBS 4.1.4.3 Tower Structure WBS 4.1.4.4 Tower Structure WBS 4.1.4.4 Test & Calibration WBS 4.1.4.5 Test & Calibration WBS 4.1.4.5 Instrument I&T Support WBS 4.1.4.7 SLAC Instrument I&T Support WBS 4.1.4.7 SLAC Mission I&T Support WBS 4.1.4.8 SLAC Mission I&T Support WBS 4.1.4.8 SLAC Mission Ops WBS 4.1.4.9 Mission Ops WBS 4.1.4.9 SSD Procurement T. Ohsugi, Hiroshima Japan, Italy, SLAC Tray Mechanical T. Borden, SLAC SLAC, Italy, Hytec Readout Electronics D. Nelson, SLAC UCSC, SLAC Tray Assembly A. Brez, INFN-Pisa Italy Tower Engineering T. Borden, SLAC SLAC, Hytec Cable Plant G. Paliaga, UCSC UCSC Tower Assembly A. Brez, INFN-Pisa O. Millican, SLAC Italy, SLAC Engineering Model SLAC Qualification Towers SLAC Flight Towers Italy

13. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 13 TKR Flight-Tower Design & Assembly Cable Plant UCSC Tower Structure (walls, fasteners) Engineering: SLAC, Hytec Procurement: SLAC SSD Procurement, Testing Japan, Italy, SLAC Electronics Design, Fabrication & Test UCSC, SLAC Tower Assembly and Test SLAC (2) Italy (16) Tray Assembly and Test Italy SSD Ladder Assembly Italy Composite Panel & Converters Engineering: SLAC, Hytec, and Italy Procurement: Italy 2592 10,368 342 648 342 18

14. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 14 Tracker Assembly Detector ladders (2592 + spares): –SSD production monitoring: Hiroshima –Edge bond SSDs, wire bond, test, encapsulate wires: 2 Italian lines Electronics multi-chip readout modules (648 + spares): –Standard chip-on-board industrial technology (quote from Teledyne) –Test/burn-in equipment and procedures supplied by UCSC Carbon-composite panels (342 + spares): –Fabricate in Italian industry –Includes converter foils and SSD bias circuits Tray assembly in 2 Italian lines (342 + spares): –Precision mounting of 4 ladders on each face –Attach electronics boards –Wire bond the electronics to the detectors, test, and encapsulate Tower assembly (2 at SLAC and 16 in Italy): –Stack 19 trays –Attach readout cables and sidewalls –Testing with the calibration system and with cosmic muons

15. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 15 Tracker Status Mechanical: –Design is complete for the tray panels and assembly fixtures, with assembly of prototypes in progress. –Mechanical/thermal testing of the detector attachment scheme and of the sidewalls is in progress. –A flexure concept and other interface issues for Tracker attachment to the grid is under study. Detectors: –The CDR of the SSD design, specifications, and prototype performance was held Jan. 30, ‘01. –A preproduction run of 400 detectors is underway at HPK. –A schedule for production of all flight units is being finalized with Hamamatsu Photonics. Electronics: –Mask layout for the design update of the 2 ASICs is in progress and close to completion. –Prototypes of the modified amplifier- discriminator design are under test. –Layout of the new PC board and flex circuits is underway. –External interfaces are well defined. Ladder and Tray Assembly: –A new ladder-assembly fixture is under test in Pisa. –Designs exist for all tray assembly fixtures. –Mockup trays are under fab for testing detector/converter attachment. Documentation: –Level-3 specs are under review. –Level-4 specs and ICDs are in progress. –Work is in progress on a database for fabrication and assembly work.

16. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 16 Tracker Documentation

17. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 17 Summary Tracker Schedule

18. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 18 Tracker Milestones Silicon-Strip Detector (SSD) Design Review01/29/01 Tracker (TKR) Requirements Review03/07/01 Tracker PDR05/30/01 LAT Instrument PDR08/06/01 Engineering Model (EM) assembly complete01/20/02 Tracker CDR05/29/02 LAT Instrument CDR08/05/02 Qual Modules A & B Ready for Integration (for calibration unit)05/15/03 Flight Modules 1 & 2 Ready for Integration (for calibration unit) 08/01/03 Flight Modules 3-16 Ready for Integration 10/01/03 – 12/24/03

19. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 19 Preliminary Tracker Cost Estimate* (Escalated K$) *DOE/NASA funding.

20. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 20 Tracker Issues Long lead time for procurement of 11,500 SSDs. –The SSD design reviews have already been completed, and procurement of flight detectors is in progress. Tight schedule for assembly of flight ladders and trays. –Two industrial assembly lines are being set up in Italy, each with enough capacity, in principle, to assemble all ladders and trays. ASIC design is the critical path for completion of the engineering model. –T&DF requirements demand extensive revision of both Tracker ASICs with respect to the BTEM versions. SLAC engineers and an outside consultant have been added to the effort to accelerate the pace of the design revisions. Thermal expansion, mass, and transparency issues place high demands on the Tracker structural design. –A solid plan has been worked out with Hytec Inc. to engineer and prototype a simple panel structure based on carbon fiber, with good progress to date. –A flexure design is in development for interfacing to the aluminum grid. –An extensive test plan is in progress in Pisa to model and prototype the converter and detector attachment for thermal testing.

21. GLAST LAT ProjectDOE/NASA Review of the GLAST/LAT Project, Feb. 13-15, 2001 R.P. Johnson, UCSC 21 Conclusions Beam tests and simulations have demonstrated that the Tracker design based on silicon-strip detectors will meet (and exceed) the LAT Science Requirements. The engineering efforts on the carbon-fiber structure, readout electronics, and assembly tooling are on track to complete the Tracker Engineering Model by CDR. A Tracker production schedule has been worked out that can meet the LAT requirements by –early procurement of SSDs, –assembly of the readout electronics in U.S. industry, –and assembly of the ladders and trays in Italian industry.