Each of the possible interaction processes can be characterized by a probability of occurrence per unit path length in the absorber. The sum of the probabilities for the individual processes is the total probability per unit length that the photon is removed from the beam. The number of primary photons interacting in a thickness t is obviously The linear attenuation coefficient obviously depends strongly on energy, since the interaction mechanisms are energy dependent. There are several different processes by which photons interact. In a photoelectric interaction, the entire incident energy of the interacting photon is deposited in the detector, while in Compton scattering, only a portion of the incident energy will generally be deposited in the detector.
Photoelectric interactions contribute to the full energy, which is usually of primary interest.
The probability of a photoelectric interaction is usually of primary interest. The Zn fraction of the CZT is typically 0.1. The probability calculation includes the effects of transmission through the Be window and of stopping in the CZT, but neglect the effects of trapping and hole tailing. Both total and photoelectric probabilities are given. Plots of the interaction probabilities are shown in Figure 1 and Figure 2.