The Timepix3 hybrid-pixel readout chip consists of a matrix made of $256\times256$ square-shaped pixels with a 55- $\mu \text{m}$ pitch, which can be hybridized to several semiconductors, such as silicon (Si) or cadmium telluride (CdTe) with thicknesses up to 5 mm. Working as an event-based readout chip, it simultaneously records the time-over-threshold (ToT) in each pixel, measuring the deposited energy, as well as the time-of-arrival (ToA), with a time resolution of 1.5 ns. In this article, we present the energy calibration of two Timepix3 chips: the first one was bump-bonded with a 300- $\mu \text{m}$ -thick silicon sensor and the second one with a 1-mm-thick CdTe sensor. Both detectors were calibrated with per pixel calibration, using the monochromatic SOurce of Low-Energy X-rays [SOLEX from Henri Becquerel National Laboratory (LNHB) at CEA Saclay] and a set of calibration-grade sealed radioactive sources. Evaluations were carried out over the energy range 6–122 keV for Timepix3 Si and 20 keV–1.332 MeV for Timepix3 CdTe. Based on this experimental procedure, an energy resolution of 2.6 keV (3.4%) at 59.5 keV was observed for Timepix3 Si. For Timepix3 CdTe, this parameter was 5.6 keV (9.4%) at 59.5 keV, 27.24 keV (4.1%) at 661.7 keV, and 47.4 keV (3.5%) at 1.332 MeV. It is the first time that CdTe bump-bonded Timepix3 spectral performances were evaluated for gamma rays above 1 MeV. The reconstruction of the full-energy peak for such high energies is possible due to the ToA information, which allows the identification of all interactions caused by a given gamma ray within the detector.

中文翻译：

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评估Timepix3 Si和CdTe混合像素探测器在X射线和Gamma射线上的光谱性能

Timepix3混合像素读出芯片由一个矩阵组成，该矩阵由 256美元/次256美元 具有55- $ \ mu \ text {m} $ 间距，可以与几种半导体（例如硅（Si）或碲化镉（CdTe））混合使用，厚度可达5毫米。作为基于事件的读取芯片，它可以同时记录每个像素中的阈值时间（ToT），测量沉积的能量以及到达时间（ToA），时间分辨率为1.5 ns 。在本文中，我们介绍了两种Timepix3芯片的能量校准：第一个通过300- $ \ mu \ text {m} $ 厚的硅传感器，第二个带有1毫米厚的CdTe传感器。使用单色低能量X射线[来自CEA Saclay的Henri Becquerel国家实验室（LNHB）的SOLEX]和一组校准级密封放射源，通过每个像素校准对两个探测器进行校准。对Timepix3 Si的能量范围是6–122 keV，对于Timepix3 CdTe的能量范围是20 keV–1.332 MeV。根据该实验程序，对于Timepix3 Si，在59.5 keV处观察到2.6 keV（3.4％）的能量分辨率。对于Timepix3 CdTe，此参数在59.5 keV时为5.6 keV（9.4％），在661.7 keV时为27.24 keV（4.1％），在1.332 MeV时为47.4 keV（3.5％）。这是首次针对1 MeV以上的伽马射线评估CdTe凸点结合的Timepix3光谱性能。