1. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz GLAST Hartmut F.-W. Sadrozinski Santa Cruz Institute for Particle Physics (SCIPP) Gamma Ray Large Area Space Telescope

2. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz GLAST Gamma-Ray Large Area Space Telescope An Astro-Particle Physics Partnership Exploring the High-Energy Universe Design Optimized for Key Science Objectives Understand particle acceleration in AGN, Pulsars, & SNRs Resolve the  -ray sky: unidentified sources & diffuse emission Determine the high-energy behavior of GRBs & Transients Proven technologies and 7 years of design, development and demonstration efforts Precision Si-strip Tracker (TKR) Hodoscopic CsI Calorimeter (CAL) Segmented Anticoincidence Detector (ACD) Advantages of modular design International and experienced team Broad E/PO program Broad experience in high-energy astrophysics and particle physics (science + instrumentation) Resources identified, commitments made by partners Management structure in place Resolving the  -ray sky

3. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz  e+ e- calorimeter (energy measurement) particle tracking detectors conversion foils charged particle anticoincidence shield GLAST Detector Concept: Pair Conversion Telescope Photon attenuation in lead

4. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Detector Design 16 towers  modularity height/width = 0.4  large field-of-view Si-strips: fine pitch 201 µm & high efficiency 0.44 X 0 front-end  reduce multiple scattering 1.05 X 0 back-end  increase sensitivity > 1 GeV CsI:  E/E <10 % 0.1-100 GeV hodoscopic  cosmic-ray rejection  shower leakage correction X TOT = 10.1 X 0  shower max contained < 100 GeV segmented plastic scintillator  minimize self-veto > 0.9997 efficiency & redundant readout TKR+CAL: prototypes + 1engineering model 16 flight +1(qual  spare) +1(spare) ACD: 1(qual) +1 flight TKR+CAL: prototypes + 1engineering model 16 flight +1(qual  spare) +1(spare) ACD: 1(qual) +1 flight Instrument TKR CAL ADC

5. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Science capabilities - sensitivity 200  bursts per year prompt emission sampled to > 20 µs AGN flares > 2 mn time profile +  E/E  physics of jets and acceleration  bursts delayed emission all 3EG sources + 80 new in 2 days  periodicity searches (pulsars & X-ray binaries)  pulsar beam & emission vs. luminosity, age, B 10 4 sources in 1 -yr survey  AGN: logN-logS, duty cycle, emission vs. type, redshift, aspect angle  extragalactic background light (  + IR-opt)  new  sources (µQSO, external galaxies, clusters) 1 yr 100 s 1 orbit 1 day 3EG  limit 0.01  0.001 LAT 1 yr 2.3 10 -9 cm -2 s -1 large field-of-view

6. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Key Science Objective: Determine the High-Energy Behavior of GRBs Important GLAST properties for achieving science objectives: Large area Low instrument deadtime (20  s) Energy range to >300 GeV Large FOV Expected Numbers of GRBs and Delayed Emission in GLAST GLAST will probe the time structure of GRB’s to the  s time scale Spectral and temporal information might allow observation of quantum gravity effects. Time between detection of photons

7. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Source Catalogs > 1 GeV M31 > 1 GeV 2 days of the survey: 344 sources GRB, AGN, 3EG + Gal. plane & halo sources rapid alert for GRBs (  15 s to the ground) sky survey data analyzed on a daily basis timely IAU circulars and WWW announcements  GRB catalog Transients or Flares precise interstellar emission model new statistical analyses including variability and spectral signatures  distinguish unresolved gas clumps  flux histories cross references with astronomical catalogs Catalog strategy

8. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz GLAST Source Localization Capability ~4500 sources 10900 sources spectral index -2 Spectral cutoff above 3 GeV s/c systematics will limit source localization capability to > 0.3` 1 - - - Expected number of AGN detected with LAT at |b| > 30 o for 2 year survey 1 year, all-sky survey source localization capability

9. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Key Science Objective: Understand Mechanisms of Particle Acceleration in AGN, Pulsars, & SNRs Multi-wavelength Observations are crucial for the understanding of Pulsars and AGN’s. Flares are largest at high energy. Overlap of GLAST with ACT’s provides Needed energy calibration. Crab Mk 501 Synchrotron Radiation Inverse Compton Flares

10. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Key Science Objective: Probe dark matter Dark Matter Candidates (e.g. SUSY particles) would lead to mono-energetic gamma lines through the annihilation process. GLAST has good sensitivity for a variety of MSSModels in the 10-100GeV range, Good energy resolution in the few % range is needed.. X X q q or  or Z 

11. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Instrument Performance (Single Source F.o.M ~ Aeff /[  (68%)] 2 ) FOV: 2.4 sr SRD: 2.0 sr

12. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Importance of Energy Reach Maximum Likelihood test statistic for detection of point sources. For typical spectral indices, the sensitivity is maximum in the GeV energy domain. At low energy, angular resolution is determined by multiple scattering  rms ~ 1/E, multiple scattering At high energy, resolution is determined by detector resolution and lever arm over which measurement is made. Lever arm restricted by fact that direction measurement must be made before 1 st bremsstrahlung photon is emitted.  rms ~  meas /d, detector resolution limit Large field of view demands small aspect ratio which means small  meas hence silicon detectors. Steeply falling spectra require large effective area to reach the detector limit.

13. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Cosmic Ray Rejection Diffuse High Latitude gamma-ray flux C.R. Rejection needed 10 5 : 1 segmented ACD segmented CAL Segmented TRK

14. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Effective area A eff ~ Converter Thickness Optimization of Converter Thickness Angular Resolution PSF(68) ~  (Converter Thickness) For Background limited Sources: (Significance) = A eff / PSF(68) 2 is independent of Converter Thickness For High Latitude Sources: Number of detected gamma’s count. # of Layers X 0 per Layer  Conversion PSF(68) @1GeV [ o ] Front 12 3.8% 38% 0.39 Back 426% 38%0.90

15. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Optimization of Pitch Angular resolution is multiple scattering dominated at low energy (<1GeV). At High Energy, measuring precision is dominant, but lever arm of measurement still limited by accumulated multiple scattering in transversed planes. At 10GeV: Changing pitch from 201 to 282 micron, increases the PSF(68) by 12%, decreases the power by 25%, increases the noise (from Leakage currents) by few %. Trade: Performance vs. Resources (Power)

16. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Beam Test Engineering Module (BTEM) Tracker End of one readout hybrid. BTEM Tracker Module with side panels removed. Single BTEM Tray The BTEM Tracker, with 16 x,y planes, undergoing tests in the SLAC test beam (11/99 – 12/99). - partially (81%) instrumented with detectors - all detectors are in 32 cm long ladders. 51,200 amp/discriminator channels. 130 detector ladders. 41,600 instrumented strips. Working VME-based TEM DAQ system.

17. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz FEM Modeling and Vibration Testing FEM analysis of (a) TKR tray deflections and (b) of a complete TKR module. Fundamental frequencies are above 550 Hz for the tray and 300 Hz for the module, clamped only at its base. Aluminum and carbon- fiber mechanical model of 10 stacked tracker trays, used by Hytec, Inc. to validate the design in vibration tests. BTEM TKR tray undergoing random vibration testing at GSFC. Lowest global support mode of the LAT is the lowest bending mode of the Grid structure at 139 Hz. (Only half of the modules are shown.)

18. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Beam Test Engineering Module (BTEM) Silicon Tracker CsI Calorimeter ACD Beam Test in SLAC’s Endstation A ( Dec 1999/Jan 2000) Test Fabrication Methods Verify Performance Resolutions Trigger Investigate Hadron Rejection

19. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Assembly of BTEM Tracker at SCIPP 4 trays, 10 eyes & 10 hands 17 trays! 2 delicate hands 2 trays and 2 observers All done and all smiles. See Eduardo de Couto e Silva’s talk

20. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz 1997 Beam Test of Prototypes Results of 1997 beam test of instrument components: Atwood, W.B. et al. 1999, NIM A (in press) Layout of hodoscopic CsI beam test calorimeter Layout of beam test tracker. For configuration on left, the converter/detector planes are 3 cm apart; on the right the separation is 6 cm.

21. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Beam Test at SLAC 1999/2000: Electrons and Photons in BTEM High efficiency (99.9%), low noise occupancy (  10 -5 )

22. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Beam Test at SLAC 1999/2000: Hadrons in BTEM Minimum Ionizing Hadron: easily rejected Interacting Hadron: generates background Beam

23. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz GLAST Schedule 2000 2001 2002 2003 2004 2005 2010 Formulation Implementation SRR NAR M-PDR M-CDR I-PDR I-CDR Inst. Delivery Launch Build & Test Engineering Models Build & Test Flight Units Inst. I&T Schedule Reserve Inst.-S/C I&T Ops. Calendar Years Procurement of ~10k Si Detectors

24. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz GLAST Development Process and Status DateActivityProgramResult 93-98Conceptual studyNASA SR&T FundsBeam Test 1998: Detector R&DDoE R&D FundsVerification of Simulations 98DoE ReviewSAGENAP Endorsement 98-00Technology DevelopmentNASA ATD BTEM Full Size Modules Manufacturing Process ASIC’s, DAQ Fall 99GLAST Instrument ProposalNASA AO GLAST Base Line Instr. (Si Tracker, CsI Calorimeter, ACD) Budget, Schedule, WBS Endorsements, MoA Feb 25, 00Decision on AOSi-GLAST selected Sept 2005Launch on Delta 2

25. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Overview of the Baseline Design 16 towers, each with 37 cm  37 cm of Si 18 x,y planes per tower –19 “tray” structures 12 with 2.5% Pb on bottom 4 with 25% Pb on bottom 2 with no converter –Every other tray rotated by 90°, so each Pb foil is followed immediately by an x,y plane 2mm gap between x and y Electronics on the sides of trays –Minimize gap between towers –9 readout modules on each of 4 sides Trays stack and align at their corners The bottom tray has a flange to mount on the grid Carbon-fiber walls provide stiffness and the thermal pathway to the grid One Tracker Tower Module

26. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Tracker Module Mechanical Design Electronics flex cables Carbon thermal panel Vectran cables run through the corner posts to compress the stack. The tray must be very stiff to avoid collisions (f 0 >500 Hz). All prototypes to date have been made with machined aluminum closeouts—high multiple scattering and poor thermal matching. A development effort is in progress at Hytec Inc. (Los Alamos, NM) to make tray structures entirely from carbon fiber. Hytec is also developing the carbon-fiber walls, hex-cell cores, and face sheets. 4  4 array of Si sensors arranged in 4 “ladders” Kapton bias circuit C-fiber face sheet Hex cell core Al closeout C-fiber face sheet 4  4 array of Pb foils Kapton bias circuit 4  4 array of Si sensors arranged in 4 “ladders” Electronics board

27. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Silicon-Strip Detectors 400  m thick, single sided 9.2 cm  9.2 cm (still to be reviewed) Strip pitch is not finalized: –194  m pitch in beam test module –201  m in the NASA proposal –May have to increase to 235  m or 282  m, depending on power allocation AC coupled with polysilicon bias (~60M  ) Beamtest module: 296 detectors from 4” wafers and 251 from 6” wafers from HPK, plus 5 of the large size from Micron. –Typical leakage: 300 nA/detector (HPK) –Bad strips: about 1 in 5000 35 9.5-cm square detectors from HPK Prototypes on order from STM Schematic layout of the detector. Bypass strips will not be used. DC pads will increase in size. A second AC pad will be added on each strip, for probing and for a second chance at wire bonding. Bypass strip

28. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Si Detector Ladders Detectors were edge bonded at SLAC by hand, using a simple alignment jig. –Some problems with vertical steps on the larger detectors. –Not ideal control of the amount of epoxy in the joint (a few joints failed during later handling). –Bond-line thickness set by hand and amount of adhesive. –Alignment in the plane: ~30  m rms. Wire bonding is straightforward. Wire bonds were encapsulated with a hard curing epoxy. –Epoxy was sprayed onto the bonds through a slit. –Control was by hand and eye (tedious). –There was some overspray. –More efficient methods need to be investigated. Or is it even needed? Edge joint and wire bonds before encapsulation Encapsulated wire bonds Schematic of the gluing jig

29. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Ladder Placement on Trays Ladders were aligned with respect to the holes in the corner posts, by pressing against a straight edge. Shims set the spacing between ladders. Silver-loaded epoxy was used to bond detectors to the bias circuit. 50  m thick tape set the adhesive bond thickness. This procedure relies upon accurate dicing of the detector wafers. Lots of issues with adhesives still need to be worked out. Handle attached to the closeout for handling during assembly. Alignment jig

30. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Tracker Electronics System See Takanobu Handa’s Poster! Boss for mechanical and thermal attachment to the wall. 28 Amplifier chips 2 Digital readout controller chip 25-pin Nanonics connector Kapton Cable down the Tower Walls Hybrid: Electrical & mechanical Challenge Redundant, ultra-low power, low-noise

31. Hiroshima 2000 : GLAST Hartmut F.-W. Sadrozinski, SCIPP, UC Santa Cruz Tracker Noise and Efficiency Noise occupancy was obtained by inducing triggers, followed by readout, at random times. Hit efficiency was measured using single electron tracks and cosmic muons. The requirements were met: 99% efficiency with <<10  4 noise occupancy. However, this was with no live trigger during the readout. We are now measuring occupancy during digital activity. Noise occupancy and hit efficiency for Layer 6x, using in both cases a threshold of 170 mV. No channels were masked. Hit efficiency versus threshold for 5 GeV positrons. 100,000 triggers