用20—1020 keV单能质子刻度CR-39固体核径迹探测器

Calibration of solid state nuclear track detector CR-39 with monoenergetic protons

用北京师范大学2×1.7MV串列加速器和400kV高压倍加器产生的20—1020keV单能质子束对CR-39固体核径迹探测器进行了刻度.为了保证质子的单能性和固体核径迹探测器上径迹密度不能超过106/cm2的要求,对两台加速器分别采用了不同方法控制质子辐照数量.在串列加速器上采用了狭缝加转盘的方法,在高压倍加器上采用了100ns单次高压脉冲扫描束流的方法,既保持了质子的单色性,又达到了质子注量小于106/cm2的要求.刻度说明CR-39记录质子径迹的阈能为约20keV(或略低于20keV);给出了CR-39测定20—1020keV质子的刻度曲线(径迹直径与蚀刻时间和质子能量的关系),可用于核反应或激光打靶产生的质子的数目、能量和角分布的测定.对高能量质子(320—1020keV)径迹的蚀刻动力学进行了研究,用理论模型计算,得到了与实验结果一致的曲线.本文采用的控制质子束流的方法,可用于类似的加速器实验刻度.

Calibration of solid state nuclear track detector CR-39 was carried out with monoenergetic protons from 2 × 1. 7 MV Tandem accelerator and 400 kV Cockcroft Walton accelerator in Beijing Normal University. To ensure the protons to have monoenergetic energy and reduce the track density to 106 cm -2,two different methods were adopted. On the tandem accelerator a slit plus rotating target plate were used to achieve the required low density irradiation while a high voltage pulse generator with pulse duration of 100 ns was used on the Cockcroft Walton accelerator. The calibration shows that the registration threshold energy of protons in CR-39 is about or a little lower than 20 keV. The response curve of track diameter vs. etching time and proton energy for protons with energy from 20 keV to 1020 keV can be used to determine the number ,energy and angular distribution of the protons produced by nuclear reaction and laser plasma acceleration. Etching dynamics of high energy protons （ 320—1020 keV） was studied. The theoretical curve is consistent with experimental data. This method of controling the proton intensity employed in this paper could also be used in similar accelerator calibration.