GLAST Rate Calculations

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GLAST Rate Calculations

• Toby Burnett
• 12 Jan 00

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Components used to measure rates

• Source model
• Geomagnetic latitude
• Spectrum
• zenith angle
• Instrument geometry
• Detector response
• ACD, tracker, CAL
• Trigger model

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How it is done overview
zenith
GLAST active box dimen.1.69 x 1.69 x 0.90

• Incoming particle, choose
• Flux (if multiple)
• E
• q(E)
• intersection with disk

q
horizon 240 below horizontalcosq -0.4
The Target sphere6 m2 cross section,(24 m2
surface area)R1.38 m.
Spacecraft 1000 kg Al hexagon
Solar panels not included
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A flux example muons

• Entry in the file source_library.xml

lt!-- special source that mimics non-interacting
cosmics --gt ltsource name"muons" flux"100"gt
ltspectrumgt ltparticle
name"mu"gt ltenergy e"100"/gt lt/particlegt
ltsolid_angle mincos"-0.4" maxcos"1.0"/gt
lt/spectrumgt lt/sourcegt

• Rate intercepting top surfaceF A DW 100 x
  (1.76)2 x p 973 Hz (or 18, also as measured)

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The background sources

• The backgndmix source

composite name
lt!-- background mixture --gt ltsource
name"backgndmix"gt ltsource
name"chime"/gt ltsource name"albedo_gamma"
/gt ltsource name"electron"/gt
ltsource name"albedo_proton"/gt lt/sourcegt
Standard proton spectrum
Electron
Protons below cutoff
Albedo from horizon
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Previous Results

• The trigger http//glast.phys.washington.edu/glas
  tsim/doc/trigger_definitions.htm

no ACD ACD
L1 5.47 kHz(9.06) 2.08 kHz(3.39)
L2 1.86 kHz(3.13) 0.96 kHz (1.72)
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Future needs

• Good model for proton albedo based on AMS
• Implement heavy component
• flux
• interactions