We present an analysis of the signal properties of a position-sensitive solid-state photomultiplier (PS-SSPM) that has an integrated resistive network for position sensing. Attractive features of PS-SSPMs are their large area and ability to resolve small scintillator crystals. However, the large area leads to a high detector capacitance, and in order to achieve high spatial resolution a large network resistor value is required. These inevitably create a low-pass filter that drastically slows what would be a fast micro-cell discharge pulse. Significant changes in the signal shape of the PS-SSPM cathode output as a function of position are observed, which result in a position-dependent time delay when using traditional time pick-off methods such as leading edge discrimination and constant fraction discrimination. The timing resolution and time delay, as a function of position, were characterized for two different PS-SSPM designs, a continuous 10 mm × 10 mm PS-SSPM and a tiled 2 × 2 array of 5 mm × 5 mm PS-SSPMs. After time delay correction, the block timing resolution, measured with a 6 × 6 array of 1.3 × 1.3 × 20 mm3 LSO crystals, was 8.6 ns and 8.5 ns, with the 10 mm PS-SSPM and 5 mm PS-SSPM respectively. The effect of crystal size on timing resolution was also studied, and contrary to expectation, a small improvement was measured when reducing the crystal size from 1.3 mm to 0.5 mm. Digital timing methods were studied and showed great promise for allowing accurate timing by implementation of a leading edge time pick-off. Position-dependent changes in signal shape on the anode side also are present, which complicates peak height data acquisition methods used for positioning. We studied the effect of trigger position on signal amplitude, flood histogram quality, and depth-of-interaction resolution in a dual-ended readout detector configuration. We conclude that detector timing and positioning can be significantly improved by implementation of digital timing methods and by accounting for changes in the shape of the signals from PS-SSPMs.
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机译：我们介绍了位置敏感型固态光电倍增管（PS-SSPM）的信号特性分析，该传感器具有用于位置传感的集成电阻网络。 PS-SSPM的吸引人的特点是它们的面积大且能够分辨小的闪烁体晶体。然而，大面积导致高检测器电容，并且为了实现高空间分辨率，需要大的网络电阻器值。这些不可避免地会产生一个低通滤波器，从而极大地减慢快速的微电池放电脉冲的速度。观察到PS-SSPM阴极输出的信号形状随位置发生显着变化，这在使用传统的时间提取方法（如前沿辨别和恒定分数辨别）时会导致位置相关的时间延迟。对于两种不同的PS-SSPM设计，表征了时间分辨率和时间延迟（随位置而定），这是一种连续的10 mm×10 mm PS-SSPM和一个平铺的2×2阵列的5 mm×5 mm PS-SSPM。经过时间延迟校正后，采用6×6阵列的1.3×1.3×20 mm 3 LSO晶体测得的块时序分辨率为8.6 ns和8.5 ns，采用10 mm PS-SSPM和PS-SSPM分别为5毫米。还研究了晶体尺寸对时序分辨率的影响，与预期相反，当将晶体尺寸从1.3 mm减小到0.5 mm时，测得很小的改进。对数字计时方法进行了研究，并显示出通过实现最先进的时间拾取来实现精确计时的巨大希望。还存在阳极侧上信号形状随位置变化的情况，这使用于定位的峰高数据采集方法变得复杂。我们研究了在双端读出检测器配置中触发位置对信号幅度，泛洪直方图质量和交互深度分辨率的影响。我们得出结论，通过实施数字定时方法并考虑到PS-SSPM信号形状的变化，可以显着改善探测器的定时和定位。
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