How to detect 中国斜草我术大学 University of Science and Technology of China Gamma-rays interact with the material in the detector through: 1.Compton scattering 2.Pair production (electron-positron pair) 106 Photoelectric Absorption Total Cross Section 103 (Experimental) pair production dominate above 10MeV Thomson Scattering Electron-Positron 100 i Pairs Compton Scattering Photonuclear Absorption 103 106 109 Photon Energy(eV)
How to detect • Gamma-rays interact with the material in the detector through: 1. Compton scattering 2.Pair production (electron-positron pair) pair production dominate above 10MeV
Compton scattering 中国斜学我术大学 University of Science and Technology of China scattered photon E=hy' E=moe2 p=hv'le ineident photon =0 AAAAAAAAAAAA E=hy p=hule target- electron P=P scattered electron
Compton scattering
pair production 中国斜学我术大学 University of Science and Technology of China Nucleus Electron (e-) Photon (y) Positron (e+) Energy threshold:E_th 2 m_e=1.022 MeV
pair production Energy threshold： E_th = 2 m_e= 1.022 MeV
Compton gamma-ray Observatory 中国斜草我术大草 University of Science and Technology of China NASA's Compton Gamma Ray Observatory EGRET COMPTEL BATSE(1 of 8) OSSE 1991-2000
Compton gamma-ray Observatory 1991-2000
Comptel 中国斜学我术大学 University of Science and Technology of China COMPTEL GAMMA RAY Gamma Ray scattered; light emitted. Light recorded. Compton scattering telescope 0.75-30MeV Two scintillator layer and coincidence detection Gamma Ray absorbed, light pulse emitted and recorded
Comptel Compton scattering telescope 0.75 - 30 MeV Two scintillator layer and coincidence detection