Improvement on the Temporal Response of CZT γ-Ray Detector by Infrared Illumination

Abstract

The temporal response of CdZnTe (CZT) detector to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula> -ray is experimentally studied in this article. Infrared (IR) illumination is utilized to improve the performance of CZT detector. The results show that with no IR illumination operated on the CZT detector, the output signal of the CZT detector appears as a short overshoot process (sharp peak) at the beginning of stable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula> -ray irradiation. After the sharp peak, a decay process follows, and finally, a stable output of CZT detector is achieved. IR illumination can eliminate the instability of CZT detector under <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula> -ray irradiation, such as the output overshoot of detector (sharp peak) during the transition state. With the increase of IR illumination intensity, the sharp peak disappears gradually and the temporal response of CZT detector follows the intensity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula> -ray irradiation without transition state. The fitting time constant of the sharp peak is in good consistency with the typical detrapping lifetime on the order of seconds. The stable current of CZT <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula> -ray detector can be improved by 8.2% due to IR illumination, which can also be explained by the prefilling effects of IR illumination on the defect level. The sharp peak in the temporal response of CZT detector is probably caused by the deep level, related to the Te antisite-related deep donors. The current uncertainty of CZT <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula> -ray detector under IR illumination is smaller than 1.4%, which is small enough to be ignored. The flux rate response of CZT detector can also be improved by IR illumination. This study will provide significant supports for the further application of CZT material in radiation measurements.