Pulse shape analysis for electron mobility study in cadmium zinc telluride gamma-ray detectors

A pulse shape analysis technique was implemented to determine electron mobility, μ_e, and electron mobility lifetime product, μ_eτ_e in cadmium zinc telluride detectors (CZT). The digital gamma finder, (DGF-4C), a single width CAMAC module produced by X-ray Instrumentation Associates (XIA), was used to extract pulse height, pulse shape, and signal rise time information. Post data acquisition analysis using the extracted information allowed measuring the μ_e and μ_eτ_e, in selected CZT samples. An almost linear relationship was observed for the signal rise time as a function of the inverse bias. This observed linear relationship was the basis for determination of μ_e using a simple linear fit. The measured signal amplitude was also used to determine μ_eτ_e using the Hecht formulation. Repeated measurements carried out confirmed the consistency of the method in determining μ_e and μ_eτ_e.