Study Of CZT Pixel Arrays Nuclear Detector And Design Of Electronics

CdZnTe(CZT) is a new developing compound semiconductor, and has been regarded as leading materials for room temperature nuclear radiation detectors. CZT nuclear radiation detectors have been widely utilized as X-ray andγ-ray telescopes and imaging instruments due to its high energy resolution, high detection efficiency and little bulk. Therefore, it has been a choice for many applications in the field of national security, astrophysics, environmental monitoring and medicine imaging system. In recent years, there is a rapid rise of attention for the investigation of CZT pixel arrays detector. And then, the research of CZT pixel arrays detector becomes a very hot issue on the radiation detection field.This paper analyzes and summarizes the recent achievement of scholars in and abroad for the CZT nuclear detection. The CZT pixel arrays nuclear radiation detection is studied in detail and the main research work is summarized as follows: Firstly, it has been studied the CZT pixel arrays nuclear radiation detector and has analyzed the characteristic of CZT crystal and the principle of CZT detector. Then, the fabrications of various parts of the system are also discussed. Secondly, the readout circuit especially for the CZT pixel arrays detector is presented in detail. The charge sensitive preamplifier is determined based on the requirement of the system characteristic and detector parameters. The designment of the shaper amplifier is accomplished based on the analysis of the preamplifier signal characteristic. The shaper amplifier is comprised of the amplification, the pole-zero cancellation, the DC offset adjust, Sallen-Key filter, 50Ωline driver and power supply filtering. In order to meet the requirement of CZT detector system, experimental results show that the shaper amplifier is to turn irregular pulse signals to standard quasi-gauss pulse signals. The simulation result of this circuit is in good accordance with the experimental result.Thirdly, the performance of the detector imaging system which includes the energy resolution and the peak efficiency has been also tested by using 662 keV Cs¹³⁷ gamma source. Experimental results show that the energy resolution of the CZT pixel arrays detector system distributes in the range of 6.25% and 7.50% for Cs¹³⁷. The photon peak efficiency which centers at about 67.5% mainly distributes between 65.0% and 72.5%. The performance of the detector imaging system meets the imaging requirements.Fourthly, the imaging experiment with a circular Cs137gamma source has been accomplished, meanwhile in order to evaluate the imaging system, modulation transfer function has been tested. Experimental results indicate that the source image can be obtained accurately, although there is lateral spread distribution which reduces from the noise.Lastly, the Lucy-Richardson algorithm, which has been also compared and analyzed, is adopted to restore the image degraded. The algorithm can properly retrieve various kinds of edges. Inner area spatial resolution has been obviously. The estimated source diameter has an error of 0.5 mm.