Precise energy calibration of pixel detector working in time-over-threshold mode
Precise energy calibration of pixel detector working in time-over-threshold mode
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DOI：
10.1016/j.nima.2010.06.183
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发表时间：
2011-05-01
影响因子：
1.4
通讯作者：
Jakubek, Jan
中科院分区：
文献类型：
--
作者：
Jakubek, Jan
半导体像素探测器Timepix（256 x 256像素，间距为55 μ m）是Medipix 2设备的后继产品。每个Timepix像素都可以在三种可能的模式中独立操作：（1）计数检测到的粒子;（2）测量粒子能量;（3）测量相互作用的时间。第二模式中的能量测量经由确定“超过阈值的时间”（TOT）来执行。在TOT模式下使用Timepix探测器进行能量测量需要了解矩阵每个像素的能量校准。这种校准在低能量范围内是非常非线性的，并且可以通过取决于四个参数的替代函数来描述。所有这些参数的确定可以通过测量和评估至少四个校准点中每个像素的响应来执行。该过程要求极高：它需要分析至少25万个光谱和33万个最小二乘拟合的性能。在这篇文章中，它表明，甚至更好的结果可以实现只有两个或三个校准点减半的最小二乘拟合所需的数量。该方法是基于对光谱峰形状的精确分析。本文还讨论了重带电粒子谱仪能量校准装置的性能。(C)2010 Elsevier B. V.保留所有权利。
The semiconductor pixel detector Timepix (256 x 256 pixels with pitch of 55 mu m) is a successor of the Medipix2 device. Each Timepix pixel can be independently operated in one of three possible modes: (1) counting of the detected particles; (2) measurement of the particle energy; and (3) measurement of the time of interaction. The energy measurement in the second mode is performed via the determination of the "time-over-threshold" (TOT). The energy measurement with the Timepix detector in TOT mode requires knowledge of the energy calibration of each pixel of the matrix. Such calibration is very nonlinear in the low energy range and can be described by a surrogate function depending on four parameters. The determination of all these parameters can be performed by measurement and evaluation of the response of each pixel in at least four calibration points. The procedure is extremely demanding: it requires the analysis of at least 250 thousand spectra and the performance of 330 thousand least-squares fits. In this article, it is demonstrated that even better result can be achieved with only two or three calibration points halving the number of least-squares fits needed. The method is based on precise analysis of the shape of spectral peaks. The article also discusses the performance of energy calibrated device for spectrometry of heavy charged particles. (C) 2010 Elsevier B.V. All rights reserved.