A three-dimensional model of CdZnTe gamma-ray spectrometer

A fully three-dimensional (3D) model of a CdZnTe semiconductor gamma-ray detector is presented. It takes into account the physical phenomena involved in the detection process and models the readout electronic response and noise. The model successively involves the finite element transient computation of the adjoint transport equation, the Monte Carlo simulation of the photon transport and the electronic signal processing including an accurate noise model. The simulation is fast and accurate because the solution of the adjoint equation allows us to obtain a continuous mapping of the induced charge collection (at any time and any interaction point) with a single 3D transient finite element computation. The simulation outputs are pulse height spectra and biparametric (rise time versus pulse height) spectra.