Estimate of large CZT detector absolute efficiency

This paper presents a simulation of the spectroscopic performance of two large CZT coplanar detectors, 1.5 × 1.5 cm² area and 1.0 cm thick, with coplanar anodes. A code, based on the GEANT libraries and classical Monte Carlo sampling, was developed to simulate experimental scenarios. This code adapts the GEANT capabilities for simulating complex detection systems for spectroscopic studies. Detectors with perfect charge transport and collection were first simulated. The code was benchmarked by simulating an HPGe detector. The result for this detector is used for estimating the code´s capabilities. Results from the simulation of this basic detector model are presented and discussed. Subsequently, the effects of a possible realistic electric field profile in a coplanar detector unable to efficiently deflect electrons to the collecting anode is studied. From the analysis of the differences found between the simulated and measured results, some conclusions relating the electrode design and detector quality are proposed.