Numerical Simulations of Charge Trapping in Germanium Strip Detectors

TL;DR

This paper presents numerical simulations of charge trapping in germanium strip detectors, aiming to understand and correct radiation damage effects to improve spectral resolution.

Contribution

It introduces a new numerical model of charge trapping that considers drift length and thermal motion, and benchmarks it against measured data.

Findings

Simulated charge collection efficiency curves as a function of interaction depth.

Comparison of simulations with experimental data shows good agreement.

The model can help in correcting radiation damage effects in germanium detectors.

Abstract

Charge trapping in germanium detectors will inevitably impact their excellent spectral performance. Disordered regions in the germanium crystal structure, either created in the material during processing or induced by radiation exposure, will affect the Charge Collection Efficiency (CCE), degrading the spectral resolution. Here we present numerical simulations of charge trapping effects on the anode and cathode signals for cross-strip germanium detectors. We discuss the assumptions behind our model of trapping, which accounts for both the drift length and thermal motion of the charge carriers. We present simulated CCE curves as a function of interaction depth within the detectors, and develop a technique for benchmarking these simulations against measured data. Comparison with measured CCE curves are presented. We are developing these numerical models with a goal of characterizing, and ultimately correcting, the effects of radiation damage on the spectral resolution of germanium cross-strip detectors.