一种高计数率的能损探测器方案研究  

A Methodological Research on the High-rate Energy Loss Measurement Detector

作　　者：卢奋华 唐述文[1,2] 傅圣威 闫铎 马朋[1,2] 杨海波[1,2] 余玉洪 章学恒[1,2] 王世陶 张永杰[1] 方芳 刘拓琦[1,2] 徐颖锋 李治垚[1,2] 刘相满 魏啸宝[1,4] 孙志宇[1,2] LU Fenhua;TANG Shuwen;FU Shengwei;YAN Duo;MA Peng;YANG Haibo;YU Yuhong;ZHANG Xueheng;WANG Shitao;ZHANG Yongjie;FANG Fang;LIU Tuoqi;XU Yingfeng;LI Zhiyao;LIU Xiangman;WEI Xiaobao;SUN Zhiyu(Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China;School of Physics,Henan Normal University,Xinxiang 453007,Henan,China)

机构地区：[1]中国科学院近代物理研究所,兰州730000 [2]中国科学院大学,北京100049 [3]兰州大学核科学与技术学院,兰州730000 [4]河南师范大学物理学院,河南新乡453007

出　　处：《原子核物理评论》2024年第1期460-466,共7页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(12375186)。

摘　　要：正在建设中的强流重离子加速器装置HIAF配备了一条先进的放射性束流线HFRS,建成后将为中国高能放射性核束物理研究提供新的机遇。HFRS的特点是流强极高(初级束流强度1×10^(11) ppp),这对用于粒子鉴别的能损探测器提出了非常高的计数率要求。传统的能损探测器对信号处理一般依次采用电荷灵敏前放、主放大器、ADC的技术路线。该方案存在电子学响应速度较慢、灵活性较差、难以处理高计数率下信号堆积严重等问题。我们对此提出一种新的适用于高计数率的能损探测器方案:以耐辐照的多次取样电离室为能损探测器,优化结构和读出方式提高探测器响应速度,使用快电荷灵敏前放对能损探测器信号初步放大后、直接用波形数字化仪采集波形再进行后续数字算法处理。并利用放射源和束流对该方案进行了验证测试。利用3组分α源测试时,对采集的波形使用数字成形算法处理,能量分辨率(FWHM)可达1.31%。在放射性次级束流线RIBLL2提供300 MeV/u的~(56)Fe束流测试中,采用时间常数τ_(f)=2μs的快电荷灵敏前放在计数率接近1 MHz时仍未发生明显堆积。HFRS(High energy FRagment Separator),an advanced in-flight radioactive separator at HIAF(High Intensity heavy ion Accelerator Facility),which is a new accelerator facility under construction in China,will provide promising opportunities for the high-energy radioactive beam physics research.The beam intensity of HFRS is extremely high(1×10^(11) ppp for the primary beam),so that the energy loss measurement detectors used for particles identification should be able to operate at very high counting rate.However,the conventional energy loss detectors suffer from slow electronics response,severe pulse pile-up,and it is difficult to operate at high counting rate.In this paper,we propose a method to measure the energy loss at higher counting rate.We use a radiation-resistant multiple sampling ionization chamber as the energy loss measurement detector,and optimize the detector structure and readout methods to enhance detector response speed,then employ fast chargesensitive preamplifiers for preliminary signal amplification,directly sample the pulse waveforms with a waveform digitizer.Finally,better performance can be obtained with subsequent digital algorithms.The method was validated and tested using both radioactive sources and beams.During the test with a compound componentsαsource,a good energy resolution(FWHM)of 1.31%was achieved.During the test with a 56Fe beam(300 MeV/u)provided by RIBLL2(the second Radioactive lon Beam Line in Lanzhou),no significant pulse pile-up was found at high counting rate even close to IMHz,when a suitable time constant(T_(f)=2μs)of the preamplifier was set.

关 键 词：HFRS 电离室 高计数率 快电荷灵敏前放 波形采样 数字成形算法 

分 类 号：O571.53[理学—粒子物理与原子核物理]