ICHEP 04 - August 16-22, 2004, Beijing Monica Pepe – INFN Perugia 1 Gamma-ray Large Area Space Telescope High Energy Gamma Physics with GLAST Monica Pepe

1ICHEP 04 - August 16-22, 2004, Beijing Monica Pepe – INFN Perugia

Gamma-ray Large Area Gamma-ray Large Area Space TelescopeSpace Telescope

High Energy Gamma Physics

with GLAST

Monica Pepe

INFN Perugia

on behalf of the GLAST-LAT Collaboration

32nd International Conference on High Energy

Physics August 16-22, 2004, Beijing, China


Use of high resolution and reliable particle detectors is now possible

in space after long and successful experience in particle physics

Study of the origin of the Universe and its evolution : strong connection between Astrophysics and HEP with many areas of collaboration

GLAST : Motivations and GoalsGLAST : Motivations and Goals

GLAST is a partnership of HEP and Astrophysics communities sharing scientific objectives and technology expertise: Designed to use very performant

particle detectors order of magnitude inprovement in sensitivity and resolution wrt previous missions Sky survey in the 10 keV – 300

GeV energy range ( poorly observed region of the electromagnetic spectrum )


The GLAST Mission

Spacecraft

GLAST Burst Monitor (GBM) 10 keV - 25 MeV(correlative transient observations)

Large Area Telescope (LAT) 20 MeV - >300 GeV

High Energy Gamma Ray observatory: 2 instruments

Observe, with unprecedented detail, sites of particle acceleration in the Universe

Explore nature highest energy processes (10 keV – >300 GeV)

Answer to important outstanding questions in high energy astrophysics raised by results from EGRET


GLAST science capabilitiesGLAST science capabilities

0.01 0.01 GeV 0.1 GeV 1 GeV 10 GeV 100 GeV 1 TeVGeV 0.1 GeV 1 GeV 10 GeV 100 GeV 1 TeV

Cosmic ray acceleration

Active Galactic NucleiUnidentified

sources

Pulsars

Gamma Ray Bursts Dark matter (A. Morselli talk)

Solar flares


Predicted sensitivities to a point source:

EGRET, GLAST, ARGO, AGILE, Milagro: 1yr survey Cherenkov telescopes: 50 hours on source

Covering the Gamma-Ray Spectrum Broad spectral coverage is crucial

for studying and understanding most astrophysical sources

GLAST and ground-based experiments cover complementary energy ranges

Performance: wide FOV and alert capabilities for GLAST / large effective area and energy reach for ground-based

Overlap: between GLAST and Cherenkov allows energy and sensitivity calibrations for ground-based instruments in the 50-500 GeV energy rangeGLAST goes a long way toward filling in the energy gap between space-based and ground-based detectors. There will be overlap for the brightest sources.

AGILE


GLAST Survey: ~10000 sources in 2

years

3rd EGRET Catalog (1991-2000)

(~ 300 sources)

Sky Map


Counting stats not included.

Cygnus region (150 x 150), E > 1 GeV

GLAST 95% C.L. radius on a 5 source, compared to a similar EGRET observation of 3EG 1911-2000

170/271 3rd EGRET Catalog sources still unidentified

provide source localization at the level of arc-minute determine Energy spectra over a broad range and Time variability on many scales correlate -ray detections with sources in other wavebands and discriminate between source models

Identifying Sources

GLAST high angular resolution and sensitivity:


AGN signature

• vast amounts of luminosity (1049 erg/s) and energy (spectra extending to GeV and TeV regions) from a very compact central volume

• high variability on a time scale <1 day

• highly-collimated relativistic particle jets

Active Galactic Nuclei

EGRET discovery:

AGN are bright and variable sources of high energy -rays

Hypotesis: relativistic plasma ejected from accreting super-massive black holes (106 - 1010 solar masses)


AGN Physics with GLAST Increase the number of known AGN from ~80 to ~5000

Distinguish leptonic (SSC/ECS) and hadronic (pp / p) models of jets by detailed spectra studies of emitted gammas

Multiwavelenght analysis combining timing and spectral information to determine acceleration and emission sites in the jet

• Study the redshift dependence of cutoff in the -ray spectra at large z to probe interaction with extragalactic background light (EBL)

• Determination of EBL may help to distinguish models of galaxy formation

Integral Flux (E>100 MeV) cm-2s-1


• most distant and intense sources of high energy -rays• cosmological distances (afterglow redshift up to z=5)• isotropic distribution in the sky • transient signal ~ 100 s time scale

EGRET: few statistics @ E>50 MeV, no temporal studies at high energies (large dead time)

Gamma-Ray Bursts

• LAT suited to study the GeV tail of the GRB spectrum

• GBM will cover the range 10 keV-25 MeV and will provide a hard X-ray trigger for GRB

GBM

LAT

GLAST: > spectral studies over full range to discriminate emission models (Synchroton, ICS) > Detection of rays during brief

intense pulses (~10 s dead time)

GLAST will detect 200 GRB’s/yr with E >100 MeV


known gamma-ray pulsars

LAT large effective area

High photon statistics, detailed

spectra

Discriminate between polar cap

and outer gap emission models of -ray production

-ray beams broaderthan their radio beams many radio quiet pulsars to be discovered

Pulsar Physics with GLAST

VELA Pulsar

LAT high time resolution and detection efficiency Direct pulsation search in the -ray band in all EGRET unidentifyed sources

Detect ~250 new gamma-ray pulsars


Systems work together to identify and measure the flux of cosmic gamma rays with energy 20 MeV - >300 GeV

e+ e–

Calorimeter

Tracker

ACD [surrounds 4x4 array of TKR towers]

Overview of LAT•Precision Si-strip Tracker (TKR)

- 18 XY tracking planes - Single-sided silicon strip detectors - (228 m pitch), 8.8 ·105 channels- Measure photon direction – Gamma ID

•Hodoscopic CsI Calorimeter (CAL)- Array of 1536 CsI(TI) crystals in 8 layers- 6.1 ·105 channels- Measure photon energy. Image the shower

•Anticoincidence Detector (ACD)- 89 plastic scintillator tiles surrounding towers- Reject background of charged cosmic rays - Segmentation removes self-veto effects at high energy

•Electronics and Flying Software DAQIncludes flexible and robust Hardware trigger and Software filters

4x4 modular array

3000 kg – 650 WElectronics and DAQ


• 16 “tower” modules, 37cm 37cm of active cross section

• 83m2 of Si, 11500 SSD, ~ 1M channels• 18 x,y planes per tower, 19 “tray” structures: - 12 with 3% X0 on top (“Front”) - 4 with 18% X0 on bottom (“Back”) – SuperGlast - 3 with no converterEvery other tray is rotated by 90°, so each converter foilis immediately followed by an x,y plane of detectors

• 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

e+ e–

particle tracking detectors

conversion foil

Anticoincidence shield

Pair-Conversion Telescope

calorimeter

GLAST Tracker Design Overview

GLAST LAT Tracker is the largest Si-tracker ever built for space applications


Gravity Probe B Launch on Delta II

• August 2004 Assembling of first tower completed

• July 2005 Completion of the LAT – Environmental testing

• December 2005

Delivery to Observatory Integration – Mate with Spacecraft and GBM and test

• February 2007Kennedy Space Flight Center

LAUNCH

GLAST Master Schedule

•May 2007

Science operation begins!

Documents

ICHEP 04 - August 16-22, 2004, Beijing Monica Pepe – INFN Perugia 1 Gamma-ray Large Area Space Telescope High Energy Gamma Physics with GLAST Monica Pepe