Abstract Silicon PIN (p-type-intrinsic-n-type) photodiodes are well suited as particle detectors. Here the interest is on a low-cost solution by repurposing a commercial device meant to be used as a light sensor. The intended application is to measure the energy spectra of electrons scattered by thin metallic foils covering small angles close to the beam of the accelerator. The main requirements for a suitable device are: 1) a low-cost solution to allow frequent replacements; 2) a small size to avoid as much as possible an unused area that contributes with unnecessary capacitance; 3) a good energy resolution; and 4) an easy repurposing as a charged-particle detector. The photodiode type BPX 65 manufactured by Osram® fulfils well these requirements. Four samples of these commercial devices have been electrically characterised with respect to reverse current and depleted-region capacitance. At the selected working point of 18 V, comfortably below the maximum rating of 20 V recommended by the manufacturer for continuous operation, the total thickness of the depleted and intrinsic regions is estimated to be ( 60 ± 3 ) μm. For the four samples considered, the measured reverse currents for a reverse bias of 18 V are around 0.1 nA, well below the typical value specified by the manufacturer (1 nA). To evaluate the performance of the device as a detector, energy spectra have been acquired for γ-rays with energies from 10 to 140 keV using 241Am, 133Ba, and 57Co radioactive sources. The resolution of the BPX 65 encountered with the γ-rays emitted by 241Am at 59.5-keV is ≈ 2.5 keV (FWHM - Full Width at Half Maximum), which is close to the value obtained with a pulser, showing that its main limitation is the electronic chain employed in the setup. The response function to monoenergetic electrons in the same energy range is studied in the companion paper.

中文翻译：

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低成本小尺寸商用 PIN 光电二极管：I. 电特性和低能光子光谱法

摘要 硅 PIN（p 型本征 n 型）光电二极管非常适合作为粒子探测器。这里的兴趣在于通过重新利用旨在用作光传感器的商业设备来实现低成本解决方案。预期应用是测量被覆盖在靠近加速器光束的小角度的薄金属箔散射的电子的能谱。对合适设备的主要要求是：1) 允许频繁更换的低成本解决方案；2) 小尺寸，尽可能避免产生不必要电容的未使用区域；3）良好的能量分辨率；和 4) 易于重新用作带电粒子探测器。Osram® 制造的 BPX 65 型光电二极管很好地满足了这些要求。这些商业器件的四个样品已经在反向电流和耗尽区电容方面进行了电气表征。在选定的 18 V 工作点，舒适地低于制造商推荐的用于连续操作的最大额定值 20 V，耗尽区和本征区的总厚度估计为 (60 ± 3) μm。对于所考虑的四个样品，在 18 V 反向偏压下测得的反向电流约为 0.1 nA，远低于制造商指定的典型值 (1 nA)。为了评估该装置作为探测器的性能，使用 241Am、133Ba 和 57Co 放射源获取了能量为 10 到 140 keV 的 γ 射线的能谱。遇到 241Am 发射的 59.5 keV γ 射线时，BPX 65 的分辨率约为 2。5 keV（FWHM - 半高全宽），接近使用脉冲发生器获得的值，表明其主要限制是设置中使用的电子链。同伴论文中研究了在相同能量范围内对单能电子的响应函数。