SLAC Scientific Policy Committee Meeting: May 12, 2001 Particle Astrophysics: GLAST Peter F. Michelson Principal Investigator and Spokesperson, GLAST LAT Collaboration Department of Physics & SLAC, Stanford University SLAC Scientific Policy Committee Meeting: May 12, 2001 Gamma-ray Large Area Space Telescope

SLAC Scientific Policy Committee Meeting: May 12, 2001 GLAST Mission  high-energy gamma-ray observatory; 2 instruments - Large Area Telescope (LAT) - Gamma-ray Burst Monitor (GBM)  launch (Sept 2005): Delta 2 class  mission operations  science - LAT Collaboration - GBM team - Guest Observers  lifetime: 5 years (minimum) Gamma-ray Large Area Space Telescope GLAST Observatory spacecraft LAT GBM GRB Coordinates Network Burst and transient Alerts Alerts Large loads TOO commands Routine Data LAT Data Spacecraft, GBM data Schedules Spacecraft data for archiving Status Command Loads Status Command Loads LAT Inst. Ops. Center LAT data handling Instrument performance Level 0,1 data processing Science Support Center Science scheduling Archiving Guest Observer Support Standard product processing Mission Ops Center Observatory safety Spacecraft health Commanding Mission scheduling GBM data handling GBM Inst. Ops. Center Instrument performance Standard product processing

SLAC Scientific Policy Committee Meeting: May 12, 2001 Large Area Telescope (LAT) e+e+ e–e–  > 40 times the sensitivity of EGRET Point Spread Function GeV GeV Large Effective Area (20 MeV – 1 TeV) Wide Field of View (2.4 sr) Good Energy Resolution (  E/E ~ 10%) Low dead time: < 20  s

SLAC Scientific Policy Committee Meeting: May 12, 2001 GLAST Science: Simulated All Sky Map One-Year All-Sky Map (E > 100 MeV) Virgo Region (E > 1 GeV) => many science objectives

SLAC Scientific Policy Committee Meeting: May 12, 2001 EGRET 3 rd Catalog: 271 sources One Year Point Source Catalog 3EG catalog AGN Galactic halo Galactic plane 5  sources from Simulated All Sky Survey Expected GLAST LAT 1 st Catalog: ~10,000 sources

SLAC Scientific Policy Committee Meeting: May 12, 2001 GLAST Science Topics Active Galactic Nuclei Isotropic Diffuse Background Radiation Cosmic Ray Production: –Identify sites and mechanisms Endpoints of Stellar Evolution –Neutron Stars/Pulsars –Black Holes Unidentified Gamma-ray Sources Dark Matter Solar Physics Gamma-Ray Bursts DISCOVERY!

SLAC Scientific Policy Committee Meeting: May 12, 2001 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, ext. galaxies, clusters) 1 yr catalog 100 s 1 orbit 1 day LAT 1 yr cm -2 s -1 3EG  limit 0.01  large field-of-view

SLAC Scientific Policy Committee Meeting: May 12, 2001 International Collaboration ~ 100 collaborators from 28 institutions ~ 100 collaborators from 28 institutions CAL access to X-ray, MeV, and TeV observatories by collaboration for multi-wavelength observations ‘mirror’ data site in Europe access to X-ray, MeV, and TeV observatories by collaboration for multi-wavelength observations ‘mirror’ data site in Europe Organizations with LAT Hardware Involvement Stanford University & Stanford Linear Accelerator Center NASA Goddard Space Flight Center Naval Research Laboratory University of California at Santa Cruz University of Washington Commissariat a l’Energie Atomique, Departement d’Astrophysique (CEA) Institut National de Physique Nuclearie et de Physique des Particules (IN2P3): Ecole Polytechnique, College de France, CENBG (Bordeaux) Hiroshima University Institute of Space and Astronautical Science, Tokyo RIKEN Tokyo Institute of Technology Instituto Nazionale di Fisica Nucleare (INFN): Pisa, Trieste, Bari, Udine, Perugia, Roma Royal Institute of Technology (KTH), Stockholm Organizations with LAT Hardware Involvement Stanford University & Stanford Linear Accelerator Center NASA Goddard Space Flight Center Naval Research Laboratory University of California at Santa Cruz University of Washington Commissariat a l’Energie Atomique, Departement d’Astrophysique (CEA) Institut National de Physique Nuclearie et de Physique des Particules (IN2P3): Ecole Polytechnique, College de France, CENBG (Bordeaux) Hiroshima University Institute of Space and Astronautical Science, Tokyo RIKEN Tokyo Institute of Technology Instituto Nazionale di Fisica Nucleare (INFN): Pisa, Trieste, Bari, Udine, Perugia, Roma Royal Institute of Technology (KTH), Stockholm TKR CAL ACD TKR CAL ACD CAL TKR CAL

SLAC Scientific Policy Committee Meeting: May 12, 2001 GLAST LAT Project: Recent & Upcoming Milestones NRC Decadal Astronomy & Astrophysics Review ranks GLAST highest priority “moderate-size” space mission for next decade: Sept 2000; 1 st joint DOE-NASA Pre-baseline “Lehman” Review of GLAST LAT Project: Feb 13-15, 2001; Launch date delayed 6 months due to NASA Mission funding issues, March 19, 2001: launch now March 2006; NASA Independent Assessment Review of GLAST Mission completed in December 2000; recommended NASA funding augmentation for mission; NASA Headquarters approves IA-recommended mission funding profile (consistent with March 2006 launch) including contingency funds to procure Delta II-H (“heavy”) launch vehicle if needed: April 10, 2001; LAT Project preparing for DOE-NASA Baseline/PDR Review this October; Preparing for Balloon Flight of Engineering Model, Summer 2001; GLAST LAT Collaboration meeting scheduled for August 1-2, 2001 at Stanford University

SLAC Scientific Policy Committee Meeting: May 12, 2001 Status of International Arrangements 2 International Agreements and 4 MoAs still being negotiated: complete drafts exist for all agreements; 3 MoAs signed (Japan & Sweden; UCSC); International Agreements delayed because Implementing Arrangement and MoU between DOE and NASA not in place; –International agreements needed with CNES (French Space Agency) and ASI (Italian Space Agency); –Lack of International Agreement and MoA with France (CNES) has impacted calorimeter schedule; French team from CEA/Saclay and IN2P3, but majority of funding from CNES; working issues night & day;

SLAC Scientific Policy Committee Meeting: May 12, 2001 GLAST LAT Organization System Engineer T. Thurston, SLAC Integration & Test M. Nordby, SLAC Mech. Systems M. Nordby, SLAC Project Controls T. Boysen, SLAC Performance & Safety Assurance D. Marsh, SLAC Principal Investigator P. Michelson, SU Project Manager W. Althouse, SLAC Instrument Design Team T. Kamae, SLAC Sci. Software R. Dubois, SLAC IOC S. Williams, SU CAL N. Johnson, NRL France, Sweden TKR R. Johnson, UCSC SLAC, Italy, Japan ACD J. Ormes, GSFC Instrument Scientist S. Ritz, GSFC E/PO L. Cominsky, SSU SSAC N. Gehrels, GSFC Collaboration Science Team Electronics & DAQ G. Haller, SLAC Instrument Design Team T. Kamae, SLAC SSAC N. Gehrels, GSFC Collaboration Science Team

SLAC Scientific Policy Committee Meeting: May 12, 2001 Collaboration Organization Senior Scientist Advisory Committee N. Gehrels, Chair P. Michelson, PI/Spokesperson G. Barbiellini, Italy R. Bellazzini, Italy E. Bloom, U.S. T. Burnett, U.S. P. Carlson, Sweden A. Djannati-Atai, France R. Dubois, U.S. –Advises PI/Spokesperson on science issues and science organization of collaboration –Implements collaboration membership policy and publication policy –Meets quarterly I. Grenier, France N. Johnson, U.S. R. Johnson, U.S. T. Kamae, Japan J. Ormes, U.S. S. Ritz, U.S. H. Sadrozinski, U.S. D. Thompson, U.S. K. Wood, U.S.

SLAC Scientific Policy Committee Meeting: May 12, 2001 Collaboration Organization Instrument Design Team –Chaired by Instrument Technical Manager, T. Kamae –Deputy Chairs: R. Bellazzini (Italy), E. Bloom (US), J. Paul (France) –Reports to Project Manager, W. Althouse –Forum for exchange of information between subsystems to maintain coordinated design; resolve issues or refer to IPO for resolution –Membership includes all subsystem managers & key system engineering personnel –IDT members obliged to attend IDT meetings; meetings open to the Collaboration –Weekly video conference meetings

SLAC Scientific Policy Committee Meeting: May 12, 2001 GLAST Mission Science Working Group Advises the GLAST Mission Project on matters related to the scientific development of the GLAST mission Jonathan Ormes, Chair, GLAST Mission Project Scientist Guido Barbiellini, Italy Elliott Bloom, USA Patrizia Caraveo, Italy Charles Dermer, (IDS), USA Brenda Dingus, (IDS), USA Neil Gehrels, Deputy Proj. Scientist, USA Isabelle Grenier, France Neil Johnson, USA Tuneyoshi Kamae, Japan Giselher Lichti, (GBM), Germany Charles Meegan, (PI-GBM), USA Peter Michelson, (PI-LAT), USA M. Pohl, (IDS), Germany David Thompson, USA Steve Thorsett, (IDS), USA Steve Ritz, Deputy Project Sci., USA Lynn Cominsky, E/PO Don Kniffen, ex officio, Program Scientist * GLAST LAT Collaboration Members

SLAC Scientific Policy Committee Meeting: May 12, 2001 GLAST Large Area Telescope (LAT) Design Instrument Pair-conversion telescope calorimeter (energy measurement) particle tracking detectors conversion foil anticoincidence shield Pair-Conversion Telescope Photon cross-section in lead e+e+ e–e– Instrument must measure the direction, energy, and arrival time of high-energy photons (20 MeV - >300 GeV) -  interactions dominated by pair-conversion: determine photon direction clear signature for background rejection -energy resolution requires calorimeter depth sufficient to measure buildup of EM shower. calorimeter segmentation useful for resolution & background rejection  - limitations on angular resolution (PSF): low E: multiple scattering many thin layers high E: hit precision & lever arm

SLAC Scientific Policy Committee Meeting: May 12, 2001 Large Area Telescope (LAT) Design Overview 16 towers  modularity height/width = 0.4  large field-of-view Si-strip detectors: total of ~10 6 ch. hodoscopic CsI crystal array  cosmic-ray rejection  shower leakage correction shower max contained < 100 GeV segmented plastic scintillator  minimize self-veto Instrument Tracker Calorimeter Anticoincidence Detector Shield 3000 kg, 650 W (allocation) 1.75 m  1.75 m  1.0 m 20 MeV – 300 GeV e+e+ e–e–  Flight Hardware & Spares 16 Tracker Flight Modules + 2 spares 16 Calorimeter Modules + 2 spares 1 Flight Anticoincidence Detector Data Acquisition Electronics + Flight Software

SLAC Scientific Policy Committee Meeting: May 12, 2001 e+e+ e–e– GLAST Large Area Telescope (LAT) Design Tracker Modules Si-strip detectors: fine pitch: 228  m, high efficiency 12 front tracking planes (x,y): 3% x 12 = 0.45 X o reduce multiple scattering 4 back tracking planes (x,y): 18% x 4 = 0.72 X o increase sensitivity > 1 GeV Prototype of one of 18 Tracker trays (detectors top & bottom)

SLAC Scientific Policy Committee Meeting: May 12, 2001 GLAST Large Area Telescope (LAT) Design Calorimeter Modules Hodoscopic Imaging Array of CsI crystals: ~ 8.5 rl depth PIN photodiode readout from both ends: 2 ch/xtal x 96 xtals/mod = 2,944 ch segmentation allows pattern recognition (“imaging”) and leakage correction Mechanical Prototype of Carbon Cell Design 8.5 rl

SLAC Scientific Policy Committee Meeting: May 12, 2001 GLAST Large Area Telescope (LAT) Design Anticoincidence Shield Segmented, plastic scintillator tile array: high efficiency, low-noise, hermetic; segment ACD sufficiently and only veto event if a track points to hit tile ACD tile readout with Wavelength Shifting Fiber

SLAC Scientific Policy Committee Meeting: May 12, 2001 X Projected Angle 3-cm spacing, 4% foils, MeV Data Monte Carlo Experimental setup in ESA for tagged photons: (errors are 2  ) GLAST Data Monte Carlo Detector Performance Verified in Detailed Beam Tests

SLAC Scientific Policy Committee Meeting: May 12, 2001 Monte Carlo - Back Monte Carlo - Front Data - Back Data - Front PSF measured for “Flight-scale” Prototype Tracker

SLAC Scientific Policy Committee Meeting: May 12, 2001 Raw Profile fitting Correlation method Energy Response measured for “Flight-scale” Prototype Calorimeter Module

SLAC Scientific Policy Committee Meeting: May 12, 2001 The PSF as a function of the reconstructed energy for data and Monte Carlo simulation. The expected 1/E behavior is clearly seen. As the photon energy increases, multiple scattering becomes less important and the PSF decreases. At high energies the point spread function is dominated by the finite spatial resolution of the silicon detectors (60 microns). The thick radiators at the back of the tracker widen the point spread function by slightly more than a factor of 2.

SLAC Scientific Policy Committee Meeting: May 12, 2001 Because of the calorimeter depth, the shower maximum is contained up to ~ 50 GeV at normal incidence. However, above a few GeV, a large amount of energy leaks out the back of the calorimeter, and the total energy measured is systematically less than the incident energy. We have employed two techniques to correct for the shower leakage. We show the raw and reconstructed energy for 20 GeV incident positrons. The resolution of the raw distribution is around 7%, while the reconstructed resolution is less than 4% by the correlation method and about 5% by profile fitting. The reconstruction method applied to Monte Carlo simulated data yields an energy resolution of 3%, suggesting that some uncertainties remain in our calibration of beam test data.

SLAC Scientific Policy Committee Meeting: May 12, 2001 Schedule Formulation Implementation SRR NAR M-CDR PDR I-CDR (Joint DOE/NASA Review) Begin LAT-S/C Integration Launch Build & Test Flight Units Inst. I&T Schedule Reserve Observatory I&T Calendar Years 1 st Joint DOE/NASA Review of GLAST LAT Baseline Review 2006 Ops. Build & Test Engineering Models