【摘要】 编码孔径相机是一种定位放射性物质的设备,对丢失放射性物质的寻找以及监测具有重要的意义。为了满足编码孔径相机对核突发事故的污染区进行实时定位,并获得污染面积和污染程度等信息,采用大面积CsI(Tl)晶体阵列与光电倍增管(PhotoMultiplier Tube,PMT)阵列耦合的方式构建高灵敏度编码相机的探测器,以此提高探测效率并减少探测时间。该探测器由121根CsI(Tl)晶体构成11×11的阵列,每根晶体的尺寸为15 mm×15 mm×15 mm,通过光导与3×3的光电倍增管阵列耦合为一个探测器模块;由4个探测器模块组成2×2的阵列作为探头部件,采用自主设计的放大滤波成型以及单端转差分电路实现探测器信号的读出处理。通过测试发现,该探测器模块在662 keV的γ射线激发下,能很好地实现各个晶体条的位置分辨,且其平均能量分辨率为9.4%。测试结果表明:该探测器在位置分辨、能量分辨率、峰位一致性以及探测效率一致性等性能方面均能够满足高灵敏度编码相机成像的设计要求。更多还原

【Abstract】 [Background] The traditional gamma camera cannot locate the contaminated area of nuclear accident,and cannot obtain the information of the contaminated area and degree in real time. [Purpose] This study aims to develop a coded aperture gamma camera detector system with large area and high sensitivity. [Methods] A detector module of large area CsI(Tl) crystal array coupled with photomultiplier tube array was proposed. It consisted of 121 CsI(Tl) crystals at the size of 15 mm×15 mm×15 mm, and 2×2 array composed of 4 detector modules was taken as γcamera detector. Multi-channel readout electronics composed of amplification, filter shaping and single-todifferential conversion circuit was independently designed for readout processing of detector signals. Finally, the performance of this detector system was evaluated by experimental tests. [Results] The results indicate that the detector module can achieve the position resolution, and its average energy resolution is 9.4% under the excitation of 662 keV γ-ray. [Conclusions] The detector system can satisfied the design requirements of coded aperture γ camera of high sensitivity in terms of position resolution, energy resolution, uniformity of peak position and detection efficiency.更多还原