Effect of crystal length on CdZnTe frisch collar device performance

In this study, the impact of crystal length on CdZnTe Frisch collar detector spectroscopic performance is investigated. Four different Frisch collar devices were designed to have identical aspect ratios of 2.0 for simulation purposes, and all four devices were later fabricated and tested. Pulse height spectra were acquired from all Frisch collar devices with a ¹³⁷Cs gamma-ray check source and the results are presented. The Frisch collar alters the weighting potential within a planar device and improves the charge collection efficiency (CCE) distribution. Thus, the parameters affecting these distributions have a great impact on the pulse height spectrum, and among those is aspect ratio (AR). All four tested devices have similar aspect ratios, and therefore also have similar weighting potential distributions. However, due to trapping effects, the CCE profiles are not the same, and shorter devices show more uniform responses to gamma rays. CCE simulations confirm that the Frisch collar device with the longest drift length has the lowest performance.