Energy-loss correction in charge sharing events for improved performance of pixellated compound semiconductors
Energy-loss correction in charge sharing events for improved performance of pixellated compound semiconductors
复制标题
DOI：
10.1016/j.nima.2019.06.017
复制
发表时间：
2019-10-01
影响因子：
1.4
通讯作者：
Lees, J. E.
中科院分区：
文献类型：
--
作者：
Bugby, S. L.;Koch-Mehrin, K. A.;Lees, J. E.
多个像素之间的电荷共享会显著降低小像素化化合物半导体探测器的能量分辨率。本文介绍了一种能量校准和重建技术，以纠正吸收的能量是分裂在两个相邻的像素，定义为双像素事件。结果得到了与1毫米厚的碲化镉探测器与250 μ m的像素间距和像素间的间距为50 μ m，使用STFC HEXITEC ASIC。电荷共享事件的比例被发现是54%的光子在59.5千电子伏时，施加3千电子伏的噪声阈值。在整个调查的能量范围内，双像素是占主导地位的共享事件类型和共享事件的绝对分数被发现是依赖于所使用的噪声thresholds.The重建技术描述减少了由于在双像素事件中的电荷共享相比，简单的电荷共享求和技术的能量分辨率的退化。与仅使用孤立事件相比，这提高了计数效率，并且与像素相加技术相比提高了能量分辨率。当仅包括孤立的像素时，在140.5 keV处的1.42 keV的FWHM能量分辨率是可实现的;包括使用像素加法的双像素事件导致3.33 keV的能量分辨率，而这里描述的重建技术导致2.14 keV的能量分辨率。当双像素事件与单像素事件相结合时，Tc-99 m的140.5keV峰内的计数增加超过100%。
The sharing of charge between multiple pixels can significantly degrade the energy resolution of small pixelated compound semiconductor detectors. This paper describes an energy calibration and reconstruction technique to correct for absorbed energy that is split over two neighbouring pixels, defined as bipixel events. Results were obtained with a 1 mm thick CdTe detector with 250 mu m pixel pitch and an inter-pixel spacing of 50 mu m, using the STFC HEXITEC ASIC.The proportion of charge sharing events was found to be 54% for photons at 59.5 keV when applying a noise threshold of 3 keV. Across the energy range investigated, bipixels were the predominant shared event type and the absolute fraction of shared events was found to be dependent on the noise threshold used.The reconstruction technique described reduces the degradation of energy resolution due to charge sharing in bipixel events compared to simple charge sharing summing techniques. This improved counting efficiency compared to using only isolated events and improved energy resolution compared to pixel addition techniques. When only isolated pixels were included, a FWHM energy resolution of 1.42 keV at 140.5 keV was achievable; inclusion of bipixel events using pixel addition results in an energy resolution of 3.33 keV whereas the reconstruction technique described here results in an energy resolution of 2.14 keV. When bipixel events are combined with single pixel events, the number of counts within the 140.5 keV photopeak of Tc-99m increased by over 100%.