流气式正比计数管低本底α/β测量仪测定总α与总β放射性时的串道消除方法探究

Cross-talk elimination in determination of grossαand grossβactivities using a low-background α/β gas-flow proportional counter

目的 探索流气式正比计数管低本底α/β测量仪测定总α与总β放射性时的串道消除方法。方法 在CLB-104型低本底α/β测量仪(流气式正比计数管低本底α/β测量仪)上,首先提高α阈值消除β粒子在α道引起的串道计数;其次下调α-β反符合阈值消除低能α粒子在β道引起的串道计数,并对β计数进行修正消除内转换电子在β道引起的计数;最后测定不同放射性水平的非盐碱水样品总α、总β放射性,并与BH 1 227型低本底α/β测量仪(固体闪烁探测器低本底α/β测量仪)上测定同一样品总α、总β放射性相比较以验证串道消除方法的有效性。结果 经消除β、α粒子在α、β道的串道计数及扣除内转电子在β道的计数后,CLB-104型低本底α/β测量仪测定同一样品的总α、总β放射性与BH1227型低本底α/β测量仪测定的总α、总β放射性一致。结论 低能α粒子、β粒子串道可通过调整相应的阈值消除,内转换电子在β道的计数可通过修正消除。

Objective To explore cross-talk elimination method in the determination of grossαand grossβactivities using a low-backgroundα/βgas-flow proportional counter.Methods A CLB-104 low-backgroundα/βgas-flow proportional counter was used in this study.First,theαthreshold was increased to eliminate the cross-talk counting caused byβparticles in theαchannel.Then,theα-βanticoincidence threshold was reduced to eliminate the cross-talk counting induced by lowenergyαparticles in theβchannel,andβcounts were corrected to eliminate the counts induced by internal convention electrons in theβchannel.Finally,grossαand grossβactivities of non-saline water samples with different activity levels were determined and compared with grossαand grossβactivities of the same samples determined on a BH1227 low-backgroundα/βsolid scintillation counter,in order to verify effectiveness of the cross-talk elimination method.Results By eliminating the cross-talk counts ofβparticles in theαchannel and the cross-talk counts ofαparticles in theβchannel,and deducting the counts of internal convention electrons in theβchannel,the grossαand grossβactivities of the same samples determined by CLB-104 were consistent with the values determined by BH1227.Conclusion Cross-talk counts induced by low-energyαparticles orβparticles can be eliminated by threshold adjustment,and the counts caused by internal convention electrons in theβchannel can be eliminated by correction.