手持式单板500MHz采样率数字化多道设计  

Design of handheld 500-MHz digital multi-channel analyzer on single board

作　　者：曾国强[1] 欧阳晓平[2] 喻明福 李强[1] 魏世龙[1] 胡传皓 杨剑[1] 葛良全[1] 

机构地区：[1]成都理工大学地学核技术重点实验室,成都610059 [2]西北核技术研究所,西安710024

出　　处：《核技术》2017年第3期27-33,共7页Nuclear Techniques

基　　金：国家自然科学基金(No.41474159);国家863计划项目(No.2012AA061803);四川省科技厅青年基金项目(No.2015JQ0035)资助~~

摘　　要：针对Cs2LiYC16:CE(CLYC)闪烁晶体、掺硼塑料闪烁体等中子/γ探测器的电流脉冲波形的甄别,需要高速数字化多道脉冲幅度分析器。采用直接耦合方式设计高速模拟前端电路,将高速模数转换器(Analog-to-Digital Converter,ADC)配合现场可编程逻辑门阵列(Field-Programmable Gate Array,FPGA)芯片实现数字化设计,在FPGA内部实现了高速数字滤波、脉冲幅度提取、基线扣除、谱线存储与传输等功能。通过嵌入式的Power PC内核,实现替代外部控制器的复杂时序功能,并挂接通用串行总线(Universal Serial Bus,USB)外设芯片实现与外部计算机的高速双向数据传输。本文还设计了低噪声、大电流的开关电源,最终实现了可脱机独立运行的手持式单板高速数字多道。通过实测数字多道的模拟前端电路大信号带宽达110 MHz,小信号带宽达200 MHz,实时采样率为500 MHz,脉冲计数通过率大于107 s-1,线性度达0.999 8,连接NaI(Tl)、掺硼塑料闪烁体、LaBr_3(Ce)等闪烁体探测器实测谱线合理,满足实际使用要求。Background： Rising time discrimination of current pulse signal by using Cs2LiYC16：CE（CLYC）, boron plastic scintillator and other neutron gamma detector, analog multi-channel and common digital multi-channel analyzer can not meet the requirements. Purpose： This study aims to develop a high-speed digital multi-channel analyzer. Methods： In this paper, by using the direct coupling way, a special high-speed analog front end circuit is designed. The high-speed analog-to-digital converter （ADC） is connected with field-programmable gate array （FPGA） could realize digital design well, then the system will finish data filtering, pulse amplitude extraction, baseline restorer, spectrum storage, transmission function and so on in the FPGA chip. The universal serial bus （USB） peripheral hangs on the embedded PowerPC kernel, the system can not only simplify the complex timing function of the external controller, but also realize high-speed data transmission with personal computer software. In this work, low noise and high current switching power supply is also designed, finally implemented a hand-held offiine independent operation of the high speed digital multi-channel single plate. Results： After the experimental tests, we can see that the digital multi-channel analog front end circuit designed in this paper used in NaI（T1）, boron plastic scintillator, LaBr3（Ce） and other scintillation detector can reach to 110 MHz of large signal bandwidth and climb to 200 MHz of small signal bandwidth. Furthermore, it also has real-time sampling rate of 500 MHz, pulse counting rate by more than 10^7 s^-l, and the linearity is up to 0.999 8. Conclusion： The ultimate measured scintillation spectrum in this paper can satisfy the actual requirement.

关 键 词：数字多道 500 MHz高速采样 中子/γ甄别 高计数率能谱 电流脉冲信号 

分 类 号：TL82[核科学技术—核技术及应用]