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Cosmic-ray Generator and comparison with BFEM data

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CR proton, electron, positron, gamma and muon generators are constructed. ... Modifying gamma-ray distribution (sharper earth rim) neutral event rate. 60Hz (data) ... – PowerPoint PPT presentation

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Title: Cosmic-ray Generator and comparison with BFEM data


1
Cosmic-ray Generator and comparison with BFEM data
  • Nov 26, 2001
  • Tsunefumi Mizuno

2
Overview of this study
  • Main purpose of this work is to construct
    reliable Cosmic-Ray generator and BFEM simulator.
    They are essential for background prediction of
    GLAST satellite.
  • Simulator and generators were first constructed
    by K. Hirano (simulator) and M. Ozaki (CR
    generator), and now being developed by H.
    Mizushima, T. Mizuno and Y. Fukazawa.
  • CR proton, electron, positron, gamma and muon
    generators are constructed.
  • Trigger rate, Hit distribution in TKR and
    reconstruction are utilized to improve the
    simulator and generator.

3
CR generator(proton/e-)
CR proton
  • Uncertain
  • Spectrum below 100 MeV
  • Angular dependence of secondary
  • (10.6sin(theta) is assumed)
  • Attenuation by the air (primary)
  • East-west effect (not implemented)

CR electron
4
CR generator (e/gamma/muon)
  • Uncertain
  • Spectrum below 100 MeV (e)
  • Angular dependence of e/muon
  • COR dependence of muon
  • Angular dependence of gamma
  • Spectrum of gamma

5
Comparison with BFEM data
Data
muon()
muon(-)
gamma
positron
electron
proton
L1T rate 500Hz (data)/ 550Hz (simulation)
neutral event rate (lt0.5MeV in ACD) 60Hz (data)/
68Hz (simulation)
6
Modifying gamma-ray distribution (sharper earth
rim)
neutral event rate 60Hz (data)/ 55Hz
(simulation)
downward upward
7
CR proton/muon filter (1)
  • The filter is developed by Michael Roterman
  • Only single and straight track is selected
    (proton/muon)
  • Select events based on hit in ACD and number of
    hits in TKR layers are

MC Protons Red MC Muons (- ) Yellow BFEM
data blue
  • Any one of top ACDs is hit
  • 8 or more TKR layers are hit
  • Vertically downward proton/muon
  • Good agreement between data and simulation

8
CR proton/muon filter (2)
  • Any one of side ACDs is hit
  • 4 or more TKR layers are hit
  • proton/muon come from horizon is selected
  • Simulation overestimates data

MC Protons Red MC Muons (- ) Yellow BFEM
data blue
  • Angular distribution of secondary is uniform
    rather than 10.6sin(theta)?

9
Narrow gamma-ray and uniform secondary charged
particles
Data
muon()
muon(-)
gamma
positron
electron
proton
L1T rate 500Hz (data)/ 450Hz (simulation)
neutral event rate 60Hz (data)/ 50Hz
(simulation)
10
Other issues to be examined
  • Low energy spectrum (especially e- and e)
  • Apply gamma-ray filter (with Kotani-san _at_ GSFC)
  • Attenuation by air (primary proton)
  • Brush-up geometry (outside Pressure Vessel)
  • Physics process of Geant4 (studied by Ogata/Kamae)
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