Ｘ線天文衛星用CCDカメラの 放射線バックグランドの評価 宇宙開発事業団 MAXI開発グループ 冨田 洋
Satellite for X-ray Astronomy (in Japan) MAXI on International Space Station （C：NASDA） ２００６～ ASTROE-2 (C：ISAS) ２００５～
CCD camera ２４．４ｃｍ 30cm CCD camera for MAXI CCD camera for ASTRO-E
X-ray CCD for MAXI 1pixel=24um*24um 1024*1024 pixel 16CCD/Camera Made by HPK ΔE / E = 2% Energy Range 0.5 – 10.0 keV 25mm
Background Geant4 Simulation (with L.E.Extension) Charged particle event (荷電粒子) Fluorescence (蛍光Ｘ線) Bremsstrahlung (制動放射Ｘ線) Geant4 Simulation (with L.E.Extension) cosmic-xray : BGD event = 1:10 (?)
simulation Isotropic cosmic particles into the whole MAXI including the CCD camera
Energy spectra of cosmic particle proton electron 108 1012 Proton/day/MeV/cm2 Electron/day/MeV/cm2 0.01 1 100 0.1 1 10 Energy (MeV) Energy (MeV) Average in ISS orbit inclination angle = 51.6degree, altitude ～ 400km
MAXI observation
A simple model particle incident Collimator : PnSnCu Body : alminium a simple model of CCD camera particle incident
Results for 3x106 Electrons Energy X,gamma-ray X-ray (<10keV) 15 2 30 5 3 100 28 11 300 293 9 1000 4092 18
other Geant4 example : Radiation Damage on CCD Enrgy deposit (Bragg curve) Damage vs Proton Fluence 290 390 Cross section view of CCD 170 520keV damage Proton flux Cross section view of CCD Miyata et al, 2002, Journal of Japanese Applied Physics
other Geant4 example : Radiation Damage on CCD >30MeV >100keV Proton distribution
summary 非宇宙Ｘ線BGDをGeant4で評価する野望を持っている。CCDの構造を入れてparticle-BGDの計算も視野に入れている 入射スペクトル、強度の正確性が問題 CCDの放射線ダメージ実験結果はGeant4を用いた計算結果と一致。特に低エネルギーが重要（～数100keV）。