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描述了如何使用蒙特卡罗方法评估产生在加速器屏蔽混凝土中的感生放射性.使用EGS4程序模拟了NaI闪烁探测器测量屏蔽混凝土块表面剂量率时,对于半径和厚度的响应.结果发现,在屏蔽混凝土块半径和厚度分别达到40cm和30cm时,表面剂量率达到饱和.研究了东京大学SF回旋加速器北墙位置8和位置9的表面剂量率,并和使用NaI闪烁探测器的测量结果进行了对比,发现模拟和实验结果符合很好.并且,获得了表面剂量和表面感生放射性之间的转换系数,对于~(60)Co转换系数为0.90(Bq.g~(-1))·(μSv·h~(-1))~(-1),对于~(152)Eu转换系数为1.26(Bq.g~(-1))·(μSv.h~(-1))~(-1)。这样,就可以通过NaI闪烁探测器表面剂量的测量结果简单评估加速器设备屏蔽混凝土中的感生放射性.
Describes how Monte Carlo method can be used to evaluate induced radioactivity in accelerator shielded concrete.The EGS4 program was used to simulate the response to radius and thickness of NaI scintillation detector when measuring the surface dose rate of shielded concrete block.It was found that, The surface dose rate is saturated when the concrete block radius and thickness reach 40cm and 30cm, respectively.The surface dose rate at the 8th and 9th positions of the north wall of the SF cyclotron at the University of Tokyo has been studied and compared with the measurement results using NaI scintillation detector , And found that the simulation and experimental results are in good agreement.And the conversion coefficient between the surface dose and the surface induced radioactivity was obtained.The conversion coefficient of ~ (60) Co was 0.90 (Bq.g -1) · (μSv) · H -1 -1), and the conversion coefficient of ~ (152) Eu was 1.26 (Bq.g -1) · (μSv.h -1) -1 . In this way, it is possible to easily evaluate the induced radioactivity in shielded concrete for accelerator devices by measuring the NaI scintillation detector surface dose.