高计数率下的实时梯形成形算法  

Real time trapezoidal shaping algorithm at high count rates

作　　者：黄宇雁[1] 宫辉[1] 李荐民[1] 

机构地区：[1]清华大学工程物理系,粒子技术与辐射成像教育部重点实验室,北京100084

出　　处：《清华大学学报（自然科学版）》2017年第5期521-524,共4页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金资助项目(11475094)

摘　　要：针对常见的指数型核脉冲信号,研究了高计数率下的梯形成形算法,特别针对计数率增大所带来的堆积问题进行了研究。提出了一种利用反卷积定位信号到达时刻的算法,有效提升了对堆积脉冲的识别能力,降低了堆积效应对能量分辨率的影响。结合上位机中用LabVIEW编写的采集软件,搭建了一套完整可靠的脉冲幅度分析系统,将梯形成形、堆积判别、能谱构建等一系列功能在现场可编程门阵列(FPGA)中实时实现。将该系统实际应用于使用硅漂移探测器的X射线衍射仪上,获得了良好的结果,在1.8×105 cps(每s计数)的条件下,所得能量分辨率达2.46%。A trapezoidal shaping algorithm was developed for common exponential nuclear signals and the pile-up effect at high count rate was studied. Deeonvolution was used for time of-arrival estimates to effectively improve the ability to recognize pile-up pulses and reduce the pile-up effect on the energy resolution. A complete pulse height analyzer was built in LabVIEW to realize real time trapezoidal shaping, pile up recognition and spectrum construction in the field-programmable gate array （FPGA）. Measurements with an X-ray diffraetometer with a silicon drift detector （SDD） give a 2.46% energy resolution at a count rate of 1.8 ×10^5 cps （counts per second）.

关 键 词：实时梯形成形 高计数率 堆积效应 X射线衍射仪 

分 类 号：TL82[核科学技术—核技术及应用]