γ-γ符合测量系统的新型前端读出电路研制

研制了一种新型前端读出电路，用于重离子治癌装置中符合测量原型系统的研究和测试。电路主要包括能量链、时间链和数据处理单元。能量链由截止频率7 MHz的抗混叠滤波器和模数转换器(ADC)组成，形成波形采样电路；时间链由高速比较器构成的定时甄别电路和时间数字转换器（TDC）组成；数据处理单元基于现场可编程门阵列(FPGA)设计实现。电路的线性度优于0.8%，噪声小于0.8 mV（RMS）。配合LaBr3单晶体条测试，能量分辨为4.5%（FWHM），在与LYSO晶体阵列配合测试时，位置映射散点图清晰。该前端读出电路性能优于CAMAC系统，具有较好的实际应用前景。

Development of New Front-end Readout Electronics for γ-γ Coincidence Measurement System

A new front-end readout electronics was developed, which was used for research and testing of the prototype coincidence measurement system in the heavy-ion cancer therapy device. The circuit mainly includes the energy measurement chain, time measurement chain and data processing unit. The energy measurement chain is composed of an anti-aliasing filter with a cut-off frequency of 7 MHz and an analog-to-digital converter (ADC), which forms a waveform sampling circuit. The time measurement chain is composed of a timing discrimination circuit formed by high-speed comparator and a time-to-digital converter (TDC). The data processing unit is designed and implemented based on a field programmable gate array (FPGA). The linearity of the circuit is better than 0.8% and the noise is less than 0.8 mV (RMS). It was tested coupled with a LaBr₃ crystal strip, and the energy resolution is 4.5% (FWHM). Meanwhile, the test was performed with the LYSO crystal detection array, and the position map scatter plot is clear. The performance of the developed front-end readout circuit is superior to the CAMAC system and has a good practical application prospect.