Liu Junlong, Hong Xu, Huang Haixi, Song Xinru, Li Lin, Zhou Chengzhuo
The College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu, 610059, China.
The College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu, 610059, China.
Appl Radiat Isot. 2024 Jul;209:111321. doi: 10.1016/j.apradiso.2024.111321. Epub 2024 Apr 11.
In nuclear radiation detection, some measured radiation counts are lost due to dead time. Estimation of dead time is necessary to restore the counting information in quantitative analysis. This study aims to propose a method for estimating dead time at high counting rate. First of all, a measurement system of pulse interval distribution was used to estimate the true input counting rate of the detection system and implemented in FPGA. Then, a digital pole-zero cancellation technique was introduced in the measurement system to decrease the decay time constant of pulse. This was aimed at mitigating the impact of pile-up on the pulse interval distribution spectrum, especially at high counting rate. The feasibility of this measurement system at high counting rate was verified by the experimental platform of EDXRF. The dead time was calculated using the measured counting rate and the estimated true input counting rate. The accuracy of the dead time relies on the precision of the estimated true count rate. When the counting rate reaches 600 kCPS, the relative error between the theoretical counting rate and the estimated true input counting rate is less than 5%.
在核辐射检测中，由于死时间的存在，一些测量到的辐射计数会丢失。在定量分析中，估计死时间对于恢复计数信息是必要的。本研究旨在提出一种在高计数率下估计死时间的方法。首先，使用脉冲间隔分布测量系统来估计检测系统的真实输入计数率，并在现场可编程门阵列（FPGA）中实现。然后，在测量系统中引入数字零极点对消技术，以减小脉冲的衰减时间常数。这旨在减轻堆积对脉冲间隔分布谱的影响，特别是在高计数率时。通过能量色散X射线荧光光谱仪（EDXRF）实验平台验证了该测量系统在高计数率下的可行性。利用测量的计数率和估计的真实输入计数率计算死时间。死时间的准确性依赖于估计真实计数率的精度。当计数率达到600千计数每秒（kCPS）时，理论计数率与估计的真实输入计数率之间的相对误差小于5%。
