Analytical model for event reconstruction in coplanar grid CdZnTe detectors

TL;DR

This paper introduces a modified analytical model for event reconstruction in coplanar grid CdZnTe detectors, improving depth accuracy by correcting for electron trapping and discussing hole transport effects.

Contribution

A new analytical formula for interaction depth reconstruction that accounts for electron trapping using existing weighting factors.

Findings

Enhanced depth reconstruction accuracy demonstrated.

Correction for electron trapping improves energy resolution.

Discussion on hole transport contributions to signals.

Abstract

Coplanar-grid (CPG) particle detectors were designed for materials such as CdZnTe (CZT) in which charge carriers of only one sign have acceptable transport properties. The presence of two independent anode signals allows for a reconstruction of deposited energy based on the difference between the two signals, and a reconstruction of the interaction depth based on the ratio of the amplitudes of the sum and difference of the signals. Energy resolution is greatly improved by modifying the difference signal with an empirically determined weighting factor to correct for the effects of electron trapping. In this paper is introduced a modified interaction depth reconstruction formula which corrects for electron trapping utilizing the same weighting factor used for energy reconstruction. The improvement of this depth reconstruction over simpler formulas is demonstrated. Further corrections due to the contribution of hole transport to the signals are discussed.