Thin CdTe detectors mounted in back-to-back configuration: spectroscopic performance for low-energy X- and gamma-rays

摘要

Thin CdTe detectors (3 x 5 mm(2) electrode area and 0.5 mm thick) mounted in a back-to-back configuration with a common anode, have been characterized. The goal was to determine the dimensions of the detector region offering good spectroscopic performance. The detector size was chosen on the basis of previous studies performed on various detectors which have shown that the width of this "best spectroscopy region" assumes a constant value of about 0.4 mm in the device thickness range 1.0-2.5 mm, while it is largely reduced when using a smaller electrode area (2 x 2 mm(2)) and 0.5 mm thick devices. The tests were performed by irradiating the detectors with a well collimated E-X = 122 keV photon beam. The results show that the edge effects observed in smaller detectors with the same configurations are significantly reduced, giving a better energy resolution, but not a wider region with good spectroscopic performance; at lower energies the effects of larger electrodes (increased electric capacitance and leakage current) result in a higher noise and an increased detection threshold. (C) 2001 Elsevier Science Ltd. All rights reserved. [References: 12]