2. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 1 GLAST:Gamma Ray Large Area Telescope The GLAST Mission and its Physics reach R.Bellazzini INFN - sez. Pisa

3. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 2 OUTLINE Introduction Pair-Conversions Telescopes The LAT Design LAT Performance GLAST Science Topics Conclusions Nature's Highest Energy Particle Accelerators

4. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 3 Profound Connection between Astrophysics & HEP This quest is changing the face of both fields. Polarization of cosmic microwave background Large scale structure The fundamental theory of Cosmic Genesis and the quest for experimental evidence has led to new and potential partnerships between Astrophysics and HEP. Some Areas of Collaboration:  Origin of cosmic rays  Dark Matter Searches  CMBR  Quantum gravity  Structure Formation  Early Universe Physics  Understanding the HE Universe

5. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 4 Sources in Third EGRET Catalog First Came EGRET Launched in April 1991 Raised many interesting issues and questions which can be addressed by a NASA mid-class mission (Delta II). Observed over 60 AGN in > 100 MeV gammas. About 1/2 dozen GRB at high energy. Measurement of diffuse gamma ray background to over 10 GeV. One hundred and seventy unidentified sources in 3rd EGRET catalog. Mystery of unidentifieds since 1970s

6. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 5 Map the High-Energy Universe GLAST Science 0.01 GeV 0.1 GeV 1 GeV 10 GeV 100 GeV 1 TeV Physics in regions of strong gravity, huge electric & magnetic fields: e.g. particle production & acceleration near the event horizon of a black hole. Use gamma-rays from AGNs to study evolution of the early universe. Physics of gamma-ray bursts at cosmological distances. Probe the nature of particle dark matter: e.g., wimps, 5-10 eV neutrino. Decay of relics from the Big Bang. GLAST pulsar survey: provide a new window on the galactic neutron star population. “Map ” the pulsar magnetosphere and understand the physics of pulsar emission. Origin of cosmic-rays: characterize extended supernovae sources. Determine the origin of the isotropic diffuse gamma-ray background. AGN Supernova Remnants

7. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 6 Pair-Conversion Telescope GLAST Concept Low profile for wide f.o.v. Segmented anti-shield to minimize self-veto at high E. Finely segment calorimeter for enhanced background rejection and shower leakage correction. High-efficiency, precise track detectors located close to the conversions foils to minimize multiple-scattering errors. Modular, redundant design. No consumables. Calorimeter (energy measurement) Particle tracking detectors Conversion foils Charged particle anticoincidence shield  e+e- Photons materialize into matter-antimatter pairs: E  -> m e + c 2 + m e - c 2

8. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 7 The Large Area Telescope (LAT) DAQ Electronics Grid Tracker Calorimeter ACD Thermal Blanket Array of 16 identical “Tower” Modules, each with a tracker (Si strips) and a calorimeter (CsI with PIN diode readout) and DAQ module. Surrounded by finely segmented ACD (plastic scintillator with PMT readout). Aluminum strong-back “Grid,” with heat pipes for transport of heat to the instrument sides.

9. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 8 The LAT Hardware

10. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 9 Tray assembling Trays are C-composite panels (Al hexcel core) Carbon-fiber walls provide stiffness and the thermal pathway from electronics to the grid.

11. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 10 GLAST Tracker Design Overview 16 “tower” modules, each with 37cm  37cm of active cross section 83m 2 of Si in all, like ATLAS 11500 SSD, ~ 1M channels 18 x,y planes per tower –19 “tray” structures 12 with 3% Pb or W on bottom (“Front”) 4 with 18% Pb or W on bottom (“Back”) 2 with no converter foils –Every other tray is rotated by 90°, so each Pb foil is followed immediately by an x,y plane of detectors 2mm gap between x and y oriented detectors Trays stack and align at their corners The bottom tray has a flange to mount on the grid. Electronics on sides of trays: –Minimize gap between towers –9 readout modules on each of 4 sides Electronics flex cables Carbon thermal panel One Tracker Tower Module

12. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 11 Prototyping of the GLAST SSD Preserie HPK detector on 6’’ wafer Gained experience with a large number of SSD (~5% of GLAST needs) Additional Prototypes: Micron (UK), STM (Italy), CSEM (Switzerland)

13. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 12 Production 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 SSD Procurement SSD Procurement Ladder Production Ladder Production Tray Assembly

14. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 13 International Collaboration ~ 100 collaborators from 28 institutions ~ 100 collaborators from 28 institutions expertise in each science topic (theory + obs.) experience in high-energy and space instrumentation access to X-ray, MeV, and TeV observatories by collaboration for multi-wavelength observations ‘mirror’ data site in Europe expertise in each science topic (theory + obs.) experience in high-energy and space instrumentation 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 Istituto 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 Istituto Nazionale di Fisica Nucleare (INFN): Pisa, Trieste, Bari, Udine, Perugia, Roma Royal Institute of Technology (KTH), Stockholm TKR CAL ACD CAL TKR CAL

15. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 14 LAT Instrument Performance Including all Background & Track Quality Cuts

16. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 15 GLAST Science Capability Key instrument features that enhance GLAST’s science reach: Peak effective area: 12,900 cm 2 Precision point-spread function (<0.10° for E=10 GeV) Excellent background rejection: better than 2.5  10 5 :1 Good energy resolution for all photons (<10%) Wide field of view, for lengthy viewing time of all sources and excellent transient response Discovery reach extending to ~TeV

17. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 16 Covering the Gamma-Ray Spectrum Broad spectral coverage is crucial for studying and understanding most astrophysical sources. GLAST and ground-based experiments cover complimentary energy ranges. The improved sensitivity of GLAST is necessary for matching the sensitivity of the next generation of ground- based detectors. GLAST goes a long ways toward filling in the energy gap between space-based and ground-based detectors—there will be overlap for the brighter sources. Predicted sensitivities to a point source. EGRET, GLAST, and Milagro: 1-yr survey. Cherenkov telescopes: 50 hours on source. (Weekes et al., 1996, with GLAST added)

18. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 17 Overlap of GLAST with ACTs Predicted GLAST measurements of Crab unpulsed flux in the overlap region with ground-based atmospheric cherenkov telescopes.

19. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 18 SNR and Cosmic-Ray Production GLAST will provide detailed maps of the galactic diffuse gamma-ray emission. measurements of SNR spectra. resolved SNR shells at  10 level. detailed maps of emission from galactic molecular clouds. EGRET View of the Galactic Anti-center GLAST Simulation of the Galactic Anti-center Geminga Crab IC 443 In order to locate SNR in the galactic plane. determine whether SNR could be the source of cosmic rays. map the distribution of cosmic rays in the galaxy. So far, no conclusive results on SNR from EGRET.

20. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 19 Cosmic-Ray Acceleration GLAST simulations showing SNR  -Cygni spatially and spectrally resolved. Energy (MeV)

21. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 20 Cosmic-Ray Acceleration Model  -ray spectrum for SNR IC 443 adapted from Baring et al. (1999) illustrating how GLAST can detect even a faint  0 -decay component. ( 1 year sky survey with 1  error bars) Faint source EGRET data

22. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 21 Active Galactic Nuclei (AGN) Active galaxies produce vast amounts of energy (10 49 erg/s) from a very compact central volume. Prevailing idea: powered by accretion onto super-massive black holes (10 6 - 10 10 solar masses). Highly variable objects with large fluctuations in luminosity in fractions of a day. Models include emission of energetic (multi-TeV), highly-collimated, relativistic particle jets. High energy  -rays emitted within a few degrees of jet axis. HST Image of M87 (1994)

23. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 22 Active Galactic Nuclei Simulation of a 1-year all- sky survey by EGRET. Simulation of a 1-year all- sky survey by GLAST. E>1 GeV! A simple extrapolation from EGRET data suggests that GLAST will detect >5000 AGN, in addition to providing far more detailed data on the known sources.

24. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 23 Measurement of AGN Spectra GLAST should readily detect low-state emission from Mrk 501 GLAST will measure blazar quiescent emission and spectral transitions to flaring states.

25. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 24 Blazar Cosmology Roll-offs in the  -ray spectra from AGN at large z probe the extragalactic background light (EBL) over cosmological distances. A dominant factor in EBL models is the era of galaxy formation: AGN roll-off may help to distinguish models of galaxy formation, e.g., Cold Dark Matter vs. Hot Dark Matter, neutrino mass contribution, … Broad spectral coverage and observations of numerous sources will be necessary to reap solid scientific results  map of the correlation between E cut-off and Z! The gamma-ray attenuation factor for  CDM models using Scalo and Salpeter models. (Bullock, Somerville, MacMinn, Primack, 1998)

26. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 25 Identifying Sources GLAST will make great improvements in our ability to resolve gamma- ray point sources in the galactic plane and to measure the diffuse background. Counting stats not included. Cygnus region (15 0 x 15 0 ), Eg > 1 GeV GLAST 95% C.L. radius on a 5  source, compared with a similar EGRET observation of 3EG 1911-2000

27. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 26 Detection of Transients In scanning mode, GLAST will achieve in one day a sufficient sensitivity to detect (5  ) the weakest EGRET sources.

28. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 27 Gamma Ray Burst GRBs are the most intense and most distant (z ~ 4.5) with fast temporal variability known sources of high energy  rays. They are an extremely powerful tool for probing fundamental physical processes and cosmic history. Life Extinctions by Cosmic Ray Jets - Physical Review Letter Vol. 80, No.26

29. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 28 Gamma-Ray Bursts GLAST will be best suited to studying the GeV tail of the gamma-ray burst spectrum. GLAST should detect  200 GRB per year with E>100 MeV, with a third of them localized to better than 10, in real time. Excellent wide field monitor for GRB. Nearly real-time trigger for other wavelength bands, often with sufficient localization for optical follow-up. With a  10  s dead time, GLAST will see nearly all of the high-E photons. 1-  localization accuracy (arc min.) Simulated one-year GLAST scan, assuming a various spectral indexes.

30. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 29 Gamma-Ray Bursts A separate instrument (NASA- MSFC) on the spacecraft will cover the energy range 10 KeV – 25 MeV and will provide a hard x-ray trigger for GRB. Energy dependent lags and the physics behind GRB temporal properties will be better studied by the broad energy coverage (10 KeV – 100 GeV) provided by GBM and LAT. The origin of ultra-energy cosmic rays suggested to be GRBS (Waxman 1995) Burst of high energy  as signature of the evaporation of primordial black holes.

31. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 30 GRBs and Quantum Gravity GRB ms pulse structure at GeV energies + Gigaparsec distances may constrain E Quantum Gravity ~ 10 19 GeV See: G. Amelino-Camelia, John Ellis et al., Nature 393 (1998) 763-765 Using GLAST, search for possible in vacuo velocity dispersion, dv ~ E/E QG of gamma rays from gamma ray bursts at cosmological distances. For many GRB (EGRET) current best estimate is, dN  /dE  ~ 1/E  2 For certain string formulations photon propagation velocity in vacuum appears increased or decreased as energy increases (granularity of space-time) v  = c(1 ± E  /E QG + O[(E  /E QG ) 2 ])  t ~  E/E QG D/c ~ 10 ms GeV -1 Gpc -1 (if E QG ~ 10 19 GeV)

32. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 31 Using only the 10 brightest bursts yr -1, GLAST would easily see the predicted energy- and distance-dependent effect. Arrival time distribution for two energy cuts 0.1 GeV and 5 GeV( cross-hatched) Test of Quantum Gravity

33. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 32 Dark Matter Problem Experimentally, in spiral galaxies the ratio between the matter density and the Critical density W is : W lum ≤ 0.01 but from rotation curves must exist a galactic dark halo of mass at least: W halo ≥ 0.03 ÷ 0.1 from gravitational behavior of the galaxies in clusters the Universal mass density is : W halo @ 0.1 ÷ 0.3 from structure formation theories: W halo ≥ 0. 3 but from big bang nucleosinthesis the Barionic matter cannot be more then: W B ≤ 0. 1 M(R) = v 2 R/G

34. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 33 Halo WIMP annihilations If SUSY uncovered at accelerators, GLAST may be able to determine its cosmological significance quickly. If true, there may well be observable halo annihilations q q  or Z  lines X X Good particle physics candidate for galactic halo dark matter is the LSP in R-parity conserving SUSY Example: X is  0 from Standard SUSY, annihilations to jets, producing an extra component of multi-GeV  flux that follows halo density (not isotropic) peaking at ~ 0.1 M   0 or lines at M  0. Background is galactic  ray diffuse. ~ ~ ~

35. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 34 Halo WIMP annihilations  lines 50 GeV 300 GeV Total photon spectrum from the galactic center from  ann. Infinite energy resolution GLAST two-year scanning mode With finite energy resolution

36. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 35 Dark Matter Searches: Neutralino GLAST  E /E ~3%  > 50 o q q  or Z  linesX X The GLAST CsI calorimeter will be the largest such device ever put into space. It is only 10 X 0 viewed from the front, but from the sides it is up to 1.5 m “thick” and well suited for precision measurements of very high- energy photons. GLAST monoenergetic line sensitivity (95% C.L. upper limit) vs. E. Colored areas are a range of MSSMs within a restricted parameter space from standard assumptions and thermal relic abundance calculations.

37. GLASTGLAST Les Rencontres de Physique de la Vallee d’Aoste – La Thuile 2001 R. Bellazini – INFN Pisa 36 Conclusions GLAST is a partnership of HEP and Astrophysics science communities. Forging partnerships between disciplines expands opportunities for doing exciting physics and maximizes the possibility of discoveries. With its large improvement in sensitivity GLAST will allow to observe sources with greater precision and higher statistics –increase by orders of magnitude the numbers of visible sources –see deeper into the universe –monitor continuously the complete, rapidly-changing high-energy gamma-ray sky –explore a good portion of the supersymetric parameter space and study the Cold and Hot Dark Matter contribution through the IR absorptionof  -ray from extragalactic sources –GRB physics at high energy. More information on GLAST at http://www.pi.infn.it/glast