With the increasingly common use of large area PMTs (photomultiplier tubes) for nuclear and particle physics experiments, information on the position dependent magnetic field effects across the PMT's photocathode is important to effectively analyze and understand data collected from PMTs. Using an automated two-dimensional scanner, we have measured the PMT response to an external magnetic field as a function of the cathode position impinged by a collimated light source. This study shows a clear dependence on the cathode position in both collection efficiency and gain of the PMT in the presence of a magnetic field. In particular, a pronounced valley in the collection efficiency is observed for certain locations of the cathode when the magnetic field is transverse to the PMT axis. The pattern of the position dependence is presented for several different magnitudes and orientations of the magnetic field relative to the PMT.
Position-Sensitive Silicon Photomultiplier Array with Enhanced Position Reconstruction by means of a Deep Neural Network
Université de Genève（日内瓦大学）；Fondazione Bruno Kessler（布鲁诺·凯斯勒基金会）；Geneva University Hospital（日内瓦大学医院）；University of Groningen, University Medical Center Groningen（格罗宁根大学，格罗宁根大学医学中心）；University of Southern Denmark（南丹麦大学）；Obuda University（奥比达大学）
Response of a Li-glass/multi-anode photomultiplier detector to $α$-particles from $^{241}$Am
测量了位置敏感锂玻璃闪烁体探测器对来自准直$^{241}$ Am源的$α$粒子的响应。闪烁光由8 X 8像素多阳极光电倍增管读出，并且对于扫描上的每个位置记录每个像素的信号幅度。像素信号强烈地依赖于位置，并且通常几个像素将记录高于给定阈值的信号（命中）。研究了该阈值对命中多重性的影响，以优化检测器的单次命中效率。
Common Iron Passive Magnetic Shielding for Scintillator Array Photomultiplier Tubes
Joint Institute for Nuclear Research（俄罗斯核联合研究所）；Institute of Nuclear Physics, Ministry of Energy of the Republic of Kazakhstan（哈萨克斯坦共和国能源部核物理研究所）；Lomonosov Moscow State University（莫斯科罗蒙诺索夫国立大学）；Massachusetts Institute of Technology（麻省理工学院）；Tel-Aviv University（特拉维夫大学）；Tsinghua University（清华大学）
Iterative reconstruction of SiPM light response functions in a square-shaped compact gamma camera
具有正方形单片闪烁体晶体和硅光电倍增器（SiPM）阵列的紧凑型伽马相机正在积极地开发用于诸如小动物成像、癌症诊断和放射性示踪剂引导的外科手术的领域中的应用。位置重建的统计方法，这是潜在的优于传统的质心方法，需要准确的知识，每个光电倍增管的空间响应。使用两个蒙特卡罗模拟和实验数据获得的相机原型，我们表明，所有的光电倍增管（光响应函数）的空间响应可以参数化与轴对称函数迭代获得的洪水场照射数据。该研究使用配备有30 x 30 x 2 mm3 LYSO晶体和8 x 8 SiPM阵列的相机原型进行，用于140 keV伽马射线。模拟表明，使用迭代方法获得的响应，用极大似然方法重建的图像仅表现出微小的失真：在22 x 22 mm 2的中心区域，X和Y方向上重建的位置与真实位置之间的平均差异不超过0.2 mm，在相机的外围不超过0.4 mm。一个类似的水平的图像失真的实验与相机原型。
Realistic Detector Geometry Modeling and Its Impact on Event Reconstruction in JUNO
Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）
Machine-Learning based photon counting for PMT waveforms and its application to the improvement of the energy resolution in large liquid scintillator detectors
