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Chandra X‐ray Observatory
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Gas discharge tubeGeiger counterGeiger counterProportional counter
Geiger‐Mueller: G > 108
Proportional: G ~ 104 ‐ 105
For proportional counter: measure charge position along the central wire to get the chargethe central wire to get the charge position.
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GLAST (Fermi) DetectorsGLAST Burst MonitorLarge Area Telescope
(20% sky coverage)
Twelve NaI low‐energy (8 keV – 1 MeV) X‐/gamma‐ray detectors facing in different directions locate source within a few degrees. Two BiGeO calorimeters
• Anticoincidence detector triggers on charged particles (so, not gamma‐rays)•W sheets convert gammas to e+/‐ pairs• Silicon strip detectors track particles
do much the same for high‐energy (150 keV – 30 MeV) gamma rays.
• Calorimeter measures particle energies
First Fermi all‐sky gamma ray map
August 2008
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Swift Satellite
ZnCdTe calorimeter array (32,768 elements) and readout electronics
BAT coded‐aperture mask
1.4 Sr field of view, 15‐150 keV
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Pierre Auger Observatory, Argentina
Air “fluorescence” (really luminescence or scintillation) and Cherenkov detectors for charged particles (cosmic rays)
Jackson, “Classical Electrodynamics”
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Cherenkov detectors
HAWC Observatory, MexicoIce Cube South PoleIce Cube, South Pole
Ice Cube: neutrino detector
HAWC: cosmic ray detector
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