Fig. 1. Charge collection efficiency varies with depth of incidence at different bias voltage

Fig. 2. Structure diagram (a) for exploring CZT crystal attenuation characteristics, the track of interaction between 20 keV, 120 keV γ-ray with crystal (b) by Geant4 simulation

Fig. 3. Geometric model of a planar CZT detector (a) and the detector model established by Geant4 (b)

Fig. 4. Variation of intrinsic detection efficiency of CZT crystals of different thicknesses with energy

Fig. 5. The absorption rate of CZT crystals varies with the thickness of the crystals with different energy

Fig. 6. Spectral response of the CZT detector to 20 keV radiation

Fig. 7. Spectral response of the CZT detector to 50 keV radiation

Fig. 8. Spectral response of the CZT detector to 100 keV radiation

Fig. 9. Spectral response of the CZT detector to 200 keV radiation

Fig. 10. Spectral response of the CZT detector to 600 keV radiation