CdTe linear arrays with integrated electronics for passive gamma emission tomography system

Abstract

These two CdTe linear arrays with integrated electronics and multi-slit collimators were designed for the verification of spent fuel rod assemblies in water pools of NPPs by the method of passive gamma emission tomography. Each array is a single module arrangement consisting of 104 CdTe detectors, installed opposite the collimator holes. The collimator is a set of separate tungsten alloy plates (100 mm thick) arranged in a special shape. The thickness of the tungsten alloy shield is 30 mm. The manufactured detectors have the simplest metal-semiconductor-metal structure with platinum contacts. The size of the crystals is 10×5×2 mm3. The detectors have an absorbing thickness of 10 mm, which is sufficient for the efficient registration of high energies. The integrated electronics are designed on the basis of ASIC VA32 HDR 14.2. The measuring part of electronics is controlled by the microprocessor device based on the DSPIC30F6014 with built-in software. The results of array calibration by registering efficiency with sources Cs-137 (222 Ci) and Co-60 (1000 Ci) are shown. The source profiles of the separate channels of the array at the shift of the array perpendicular to the source radiation ray are demonstrated. The measurement results of the radiation flux intensities at an input quanta count rate of up to 4×106 quanta/s (E=662 keV), with and without correction for transit characteristics, are presented. No polarization of the CdTe detectors was observed during the testing of linear arrays.