高计数率α、β粒子辐射检测方法研究与实现

Research and implementation of high counting rate α-and β-particle radiation detecting method

提出一种用单探测器实现α、β粒子辐射同时检测的方法和系统。设计出纹波小于20 mV的±12 V、±5 V直流电源,保证了耦合输出信号的灵敏度;改用检波电路将信噪比提高了12.1 dB,同时将反冲信号由-700 mV抑制到+200 mV以内,还彻底抑制了比较器产生的反串信号,省去"极零相消"电路。采用双路单稳态触发器实现α道对β道的有效屏蔽。经实测,本检测系统对302cps源的β粒子辐射计数率可达79%,提高了22%;β道对α道的串道比为1%,降低了1%;对6190cps源的α粒子辐射计数率可达54%,提高了9%;α道对β道的串道比为12%,降低了17%。

A radiation detecting method and system was developed,which can detect the α-and β-particles simultaneously with single detector. The ± 12 V and ±5 V DC power supply modules with ripple voltage less than 20mV were designed to increase the coupler output signal sensitivity. With the detecting circuit, the SNR is increased by 12.1 dB and the recoil signal is restrained from -700 mV to under ＋200 mV. The crosstalk signal from the comparator is thoroughly restrained and the pole-zero cancellation circuits are also omitted. Two channel monostable trig-gers are used to realize the effective shielding of the α channel to β channel. The experiments results indicate that the count rate of the proposed detecting system can reach to 79% for β-particle radiation from 302 cps source, which is increased by 22% , and the cross-talk ratio of β channel to α channel is 1% , which is decreased by 1%. While the count rate can reach to 54% for α-particle radiation from 6190 cps source, which increased by 9% , and the cross-talk ratio of α channel to β channel is 12% ,which is decreased by 17%.