Performance of a new CdZnTe portable spectrometric system for high energy applications

A new cadmium zinc telluride (CZT) portable spectrometric system called OMEGA has been developed at CEA/LETI for high-energy applications like spent fuel assay in response to needs in the nuclear industry. The unit has been designed to operate at room temperature under water. The CZT OMEGA system is based on a single 10×10×10 mm³ CZT detector associated with a single electronics channel. To improve performance, the system incorporates several technologies including: an electrode design named the "Mixed" electrode which combines a noncontacting Frisch grid and the pixel field effect to obtain maximum sensitivity from the 10×10×10 mm³ CZT detector, a single hybrid preamplifier designed to reduce noise, an electronics board configured to enhance count rate capabilities and finally, electron bi-parametric (BP) correction (pulse height corrected via measurement of rise time) to improve both energy resolution and detection efficiency. This paper reports the most recent results obtained with the CZT OMEGA spectrometric system at high energy (¹³⁷Cs and ¹⁵²Eu sources) at both low and high count rate: spectrometric performance shows an energy resolution of 1% FWHM at 662 keV (0.8% at 1408 keV) from 1 kcps to 50 kcps, deteriorating to 2% FWHM at 200 kcps.