The single photon sensitivity of the Adaptive Gain Integrating Pixel Detector
The single photon sensitivity of the Adaptive Gain Integrating Pixel Detector
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自适应增益积分像素探测器的单光子灵敏度
DOI：
10.1016/j.nima.2012.08.008
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
H. Graafsma
中科院分区：
文献类型：
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作者：
J. Becker;D. Greiffenberg;U. Trunk;Xintian Shi;R. Dinapoli;A. Mozzanica;B. Henrich;B. Schmitt;H. Graafsma
单光子灵敏度是某些探测系统的重要特性。本文研究了自适应增益积分像素探测器（AGIPD）的单光子灵敏度及其对探测器噪声值的依赖性。由于欧洲X射线自由电子激光器（XFEL）的特殊要求，AGIPD通过对总信号进行积分来确定每个像素中吸收的光子数。光子计数是在阈值数据集上离线完成的。结果表明，AGIPD对能量为8 keV或更高的单光子敏感（探测效率约为50%，由于每106个像素的噪声，小于1个计数）。如果最终噪声在可能范围的低端（200-400个电子），则也可以在5 keV束能量下实现单光子灵敏度。结果表明，当噪声足够低时，电荷求和方案是有益的。事件的总检测率增加，并且在相邻像素中多次计数单个事件的概率降低高达40倍。AGIPD的进入窗口允许3 keV光子以大约70%的概率到达敏感体积。因此，探索AGIPD的低能量性能，发现在3 keV射束能量下的最大噪声基底低于0.035次/像素/帧。根据噪声水平和所选阈值，该值可以减小约10倍。即使单光子灵敏度，如在这项工作中定义的，没有给出，在这个能量下成像仍然是可能的，允许泊松噪声限制性能的信号显着高于本底噪声。
Single photon sensitivity is an important property of certain detection systems. This work investigated the single photon sensitivity of the Adaptive Gain Integrating Pixel Detector (AGIPD) and its dependence on possible detector noise values. Due to special requirements at the European X-ray Free Electron Laser (XFEL) the AGIPD finds the number of photons absorbed in each pixel by integrating the total signal. Photon counting is done off line on a thresholded data set. It was shown that AGIPD will be sensitive to single photons of 8keV energy or more (detection efficiency ⪢50%, less than 1 count due to noise per 106pixels). Should the final noise be at the lower end of the possible range (200–400 electrons) single photon sensitivity can also be achieved at 5keV beam energy. It was shown that charge summing schemes are beneficial when the noise is sufficiently low. The total detection rate of events is increased and the probability to count a single event multiple times in adjacent pixels is reduced by a factor of up to 40. The entry window of AGIPD allows 3keV photons to reach the sensitive volume with approximately 70% probability. Therefore the low energy performance of AGIPD was explored, finding a maximum noise floor below 0.035 hits/pixel/frame at 3keV beam energy. Depending on the noise level and selected threshold this value can be reduced by a factor of approximately 10. Even though single photon sensitivity, as defined in this work, is not given, imaging at this energy is still possible, allowing Poisson noise limited performance for signals significantly above the noise floor.