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arXiv 1903.06147physics.ins-det
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光谱光子计数像素探测器的死时间校正

Dead-time correction for spectroscopic photon counting pixel detectors

Gabriel Blaj

摘要:

在过去的十年中,现代光子计数像素探测器在同步加速器光源和其他光源的应用中实现了革命。当前探测器的局限性之一是由于导致光子堆积的死区时间而导致计数线性度降低或甚至在高计数率下瘫痪。现有的死时间和堆积模型无法再现死时间对光子计数的影响的复杂性,导致在最好的特定探测器的经验校准,不精确的线性化方法,或没有线性化。随着许多同步加速器光源计划进行显著的亮度升级,并且自由电子激光计划转向准连续操作模式,这个问题在未来将会增加。我们在这里提出了第一个模型,其使用具有恒定电流放电的光谱光子计数像素检测器中的模拟前置放大器的实际行为(例如,Medipix系列探测器)推导出更精确的分析模型和最佳线性化方法。特别是,对于每个像素至少有两个计数器的探测器,我们完全消除了校准的需要,或以前的知识的探测器和光束参数(死区时间,积分时间,大套同步加速器填充模式)。这是总结在几个模型越来越复杂和准确性。最后,我们提出了一个一般的经验方法适用于任何特定的情况下,分析方法是不够精确。

英文摘要:

Modern photon counting pixel detectors enabled a revolution in applications at synchrotron light sources and beyond in the last decade. One of the limitations of current detectors is reduced counting linearity or even paralysis at high counting rates, due to dead-time which results in photon pile-up. Existing dead-time and pile-up models fail to reproduce the complexity of dead-time effects on photon counting, resulting in empirical calibrations for particular detectors at best, imprecise linearization methods, or no linearization. This problem will increase in the future as many synchrotron light sources plan significant brilliance upgrades and free-electron lasers plan moving to a quasi-continuous operation mode. We present here the first models that use the actual behavior of the analog pre-amplifiers in spectroscopic photon counting pixel detectors with constant current discharge (e.g., Medipix family of detectors) to deduce more accurate analytical models and optimal linearization methods. In particular, for detectors with at least two counters per pixel, we completely eliminate the need of calibration, or previous knowledge of the detector and beam parameters (dead-time, integration time, large sets of synchrotron filling patterns). This is summarized in several models with increasing complexity and accuracy. Finally, we present a general empirical approach applicable to any particular cases where the analytical approach is not sufficiently precise.

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