A three-dimensional model of CdZnTe gamma-ray detector and its experimental validation

Abstract

A fully three-dimensional (3-D) model of a semiconductor gamma-ray detector is presented. The model takes into account the gamma-ray and charge collection physical phenomena involved in the detection process and models the readout electronic response and noise. The model successively involves the Monte Carlo simulation of the photon transport, the finite element transient computation of the adjoint transport equation, and the electronic signal processing including an accurate noise model. The simulation is possible because the solution of the adjoint equation allows us to obtain a continuous mapping of the induced charge collection efficiency (at any time and any interaction point) with a single 3-D transient finite element computation. The simulation outputs are pulse height spectra and bi-parametric (rise time versus pulse height) spectra. The model has been validated on two applications. The first application is a CdZnTe monolithic pixelated detector at medical energies. The detector dimension is10 10 5 mm, with a pixel size of 2 2 mm, and a 2.5-mm pitch. The second application is a gamma-ray spectrometric single-channel probe for 200-keV to 2-MeV photons combining a small anode and the capacitive Frisch grid structure. The detector dimension is 10 10 9 mm. Simulated and experimental results are compared. In both cases, the comparison between simulated and experimental spectra is qualitatively good for pulse height spectra, as well as bi-parametric spectra.

Charge sharing on monolithic CdZnTe gamma-ray detectors: A simulation study

“…Recently, an accurate model for determining the threedimensional distribution of charge pulses produced in a semiconductor detector has been developed [3,4]. It is divided into three parts.…”

“…The detector response is modeled with the adjoint method [3,4] to obtain a map of the charge induction efficiency (CIE) (Fig. 3).…”

ASIC with Multiple Energy Discrimination for High-Rate Photon Counting Applications

“…Considerable progress in fabrication processing and electrode configurations make now available pixel sensors that, using the small pixel effect, are essentially sensitive to electrons only, can provide partial compensation of the electron trapping, and can exhibit an induced charge collection time much shorter than the sensor transit time. It becomes possible to efficiently operate these detectors at pixel rates well above the MHz while maintaining high efficiency and good energy and spatial resolution [10][11][12][13][14][15].…”

Simulation and experimental results on monolithic CdZnTe gamma-ray detectors

“…This agreement may be impossible to find if the material is not homogeneous. Correct energy with interaction depth allows working with all the transport properties and reduces tailing as previously shown on HPBM monolithic CZT detectors [1].…”

“…Simulations have been made with a three-dimensional model of a semiconductor gamma-ray detector: ULYSSE [1]. ULYSSE takes into account the gamma ray and charge collection physical phenomena involved in the detection process and models the readout electronic response and noise.…”