RESUMO
This work is focused on the use of a CZT detector for a radiation mapping with an industrial robotic arm. Measurements were carried out within the RadioRoSo experiment (Radioactive Waste Robotic Sorter), under the umbrella of EU FP7 project ECHORD++. In tests with a dual-arm robot and standard point sources of 137Cs and 60Co, a Magnox waste was mimicked. Thereafter, for relevant measurement geometries and selected shielding materials, full energy peak efficiencies were calculated using the MCNP transport code. Simulated FEP efficiency values were used for minimum detectable activity assessments for expected measurement conditions. Obtained results would be also applicable for cases of shielded lost/orphan point-like sources.
RESUMO
This paper describes an application of infrared light-induced de-polarization applied on a polarized CdZnTe detector working under high radiation fluxes. We newly demonstrate the influence of a high flux of X-rays and simultaneous 1200-nm LED illumination on the spectroscopic properties of a CdZnTe detector. CdZnTe detectors operating under high radiation fluxes usually suffer from the polarization effect, which occurs due to a screening of the internal electric field by a positive space charge caused by photogenerated holes trapped at a deep level. Polarization results in the degradation of detector charge collection efficiency. We studied the spectroscopic behavior of CdZnTe under various X-ray fluxes ranging between 5 × 10 5 and 8 × 10 6 photons per mm 2 per second. It was observed that polarization occurs at an X-ray flux higher than 3 × 10 6 mm - 2 ·s - 1 . Using simultaneous illumination of the detector by a de-polarizing LED at 1200 nm, it was possible to recover X-ray spectra originally deformed by the polarization effect.
