Wang Zhonghai, Sun Xishan, Lou Kai, Joseph Meier, Zhou Rong, Yang Chaowen, Zhu Xiaorong, Shao Yiping
College of Physical Science and Technology, Key Laboratory of Radiation Physics and Technology, Ministry of Education, Sichuan University, Chengdu, China.
Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Nucl Instrum Methods Phys Res A. 2016 Apr 21;816:40-46. doi: 10.1016/j.nima.2016.01.081. Epub 2016 Feb 4.
One technical challenge in developing a large-size scintillator detector with multiple Silicon Photomultiplier (SiPM) arrays is to read out a large number of detector output channels. To achieve this, different signal multiplexing circuits have been studied and applied with different performances and cost-effective tradeoffs. Resistor-based multiplexing circuits exhibit simplicity and signal integrity, but also present the disadvantage of timing shift among different channels. In this study, a resistor-based multiplexing circuit for a large-sized SiPM array readout was developed and evaluated by simulation and experimental studies. Similarly to a multiplexing circuit used for multi-anode PMT, grounding and branching resistors were connected to each SiPM output channel. The grounding resistor was used to simultaneously reduce the signal crosstalk among different channels and to improve timing performance. Both grounding and branching resistor values were optimized to maintain a balanced performance of the event energy, timing, and positioning. A multiplexing circuit was implemented on a compact PCB and applied for a flat-panel detector which consisted of a 32×32 LYSO scintillator crystals optically coupled to 5×5 SiPM arrays for a total 20×20 output channels. Test results showed excellent crystal identification for all 1024 LYSO crystals (each with 2×2×30 mm size) with Na flood-source irradiation. The measured peak-to-valley ratio from typical crystal map profile is around 3:1 to 6.6:1, an average single crystal energy resolution of about 17.3%, and an average single crystal timing resolution of about 2 ns. Timing shift among different crystals, as reported in some other resistor-based multiplexing circuit designs, was not observed. In summary, we have designed and implemented a practical resistor-based multiplexing circuit that can be readily applied for reading out a large SiPM array with good detector performance.
开发具有多个硅光电倍增管（SiPM）阵列的大型闪烁体探测器时面临的一个技术挑战是读出大量探测器输出通道。为实现这一目标，人们研究并应用了不同的信号复用电路，它们在性能和性价比方面各有不同的权衡。基于电阻的复用电路具有简单性和信号完整性，但也存在不同通道之间定时偏移的缺点。在本研究中，通过仿真和实验研究开发并评估了一种用于大型SiPM阵列读出的基于电阻的复用电路。与用于多阳极光电倍增管的复用电路类似，接地电阻和分支电阻连接到每个SiPM输出通道。接地电阻用于同时减少不同通道之间的信号串扰并改善定时性能。对接地电阻和分支电阻的值进行了优化，以保持事件能量、定时和定位的平衡性能。在一块紧凑型印刷电路板上实现了一个复用电路，并将其应用于一个平板探测器，该探测器由32×32的LYSO闪烁体晶体组成，这些晶体与5×5的SiPM阵列进行光学耦合，总共20×20个输出通道。测试结果表明，在钠源照射下，对于所有1024个LYSO晶体（每个晶体尺寸为2×2×30 mm）都有出色的晶体识别能力。从典型晶体图谱轮廓测得的峰谷比约为3:1至6.6:1，平均单晶能量分辨率约为17.3%，平均单晶定时分辨率约为2 ns。未观察到如其他一些基于电阻的复用电路设计中所报道的不同晶体之间的定时偏移。总之，我们设计并实现了一种实用的基于电阻的复用电路，它可轻松应用于读出大型SiPM阵列，并具有良好的探测器性能。
