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Gamma-Ray Astronomy with GLAST

May 24, 2008Toby Burnett

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GLAST meets its spacecraft, last December

GLAST meets its launch vehicle (last week)

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Launch: from Cape Canaveral – June 3, 2008

We are #332

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GLAST already on MySpace!

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But what is gamma-ray astronomy?

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relevant names:

masscharge particle

cosmic rayprotonmuonphoton x-ray gamma ray radio wave visible light ultraviolet infrared

wavewave lengthfrequency

flux spectrum

telescope

magnetic fieldenergy Joule (J)

electron volt (eV)

AAA batterykilowatt hourgallon of gas

The cosmic ray spectrum

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Flu

x

Energy

Questions:1.Which astronomical objects are the origin of cosmic rays?2.Above the “Knee”, can we locate the origins?

astronomy possible here?

Astronomy with photons

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Green: E =2.5 eV =500 nm

wave-like particle-like

The atmosphere matters!

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Telescopes & particle detectors

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e+ e– calorimeter (energy measurement)

particle tracking detectors

conversion foil

anticoincidenceshield

Pair-Conversion Telescope

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Optical telescope (SDSS):A fancy camera with a CCD photon detector

Schematic for a gamma-ray detector

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GAP!

GLAST

(Mike Turner 1989)

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12log10(E/1 MeV)

E*f

lux,

(m

-2 s-1

)

galactic protons

He, CNO

Galactic electrons

Albedo gamma secondary protons

secondary e±

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LAT: 20 MeV – >300 GeV

GBM: 10 keV – 25 MeV

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Large Area Telescope (LAT)

GLAST Burst Monitor (GBM)

An International Science Mission

Large Area Telescope (LAT)

GLAST Burst Monitor (GBM)

Spacecraft (General Dynamics

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• Precision Si-strip Tracker 18 XY tracking planes. Single-sided silicon strip detectors (228 m pitch) Measure the photon direction; gamma ID.

• Hodoscopic CsI Calorimeter Array of 1536 CsI(Tl) crystals in 8 layers. (8 X0) Measure the photon energy; image the shower.

• Segmented Anticoincidence Detector (ACD) 89 plastic scintillator tiles. Reject background of charged cosmic rays; segmentation removes self-veto effects at high energy.

• Electronics System Includes flexible, robust hardware trigger and software filters.

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Calorimeter

e+ e–

ACD

Tracker1.7 m

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Galactic center

3C279 (blazar)

Vela ( radio pulsar)

Crab (radio pulsar)

Geminga (radio-quiet pulsar)

PKS 0202-512 (blazar)

Isolated neutron star?

SN remnant?

Point things: near and far Diffuse things: CR

interactions in matter

Orion Cloud

LMC

EGRET all-sky survey (E>100 MeV)

Extragalactic diffuse

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GLAST’s view of the sky

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GLAST sources found (simulation)

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