激光尾波场电子轰击多层靶的正电子产额模拟计算

Simulation of Positron Yield Increased by the Interaction of Laser Wakefield Electrons With Multi-layer Targets

利用超强激光驱动相对论正电子产生时,为提高正电子的产额,提出了基于激光尾波场电子轰击多层靶的方案,将转换靶由单层厚靶替换为多层薄靶,并通过蒙特卡罗程序FLUKA对尾波场电子轰击多层靶及单层靶产生正电子的全过程进行了模拟分析。结果表明,多层靶的正电子总产额约为单层靶的2.4倍,尾场电子的能量利用率是单层靶的1.2倍;对于多层靶,正电子产额最大时,子靶厚度d、靶间距L和靶半径R之间的关系满足RL/d为常数,正电子产额随靶层数的增加而增大,当靶层数大于15时,正电子产额不再明显增加。

To increase the yield of positron,a scheme of bombarding multi-layer targets with laser wakefield electrons(LWFE)is proposed.In this scheme,a single-layer conversion target is replaced by multi-layer targets.The whole process of positron generation with wakefield electrons bombarding on single-layer and multi-layer targets is simulated and analyzed by using Monte Carlo Program FLUKA.The results show that the total positron yield of multi-layer targets is about 2.4 times of that of the single-layer target,and the energy utilization efficiency of wakefield electrons is 1.2 times of that of the single-layer target.In addition,for multi-layer targets,when the positron yield reaches the maximum,the value of RL/dis a constant,and the positron yield increases with the increase of the number of the target layers.When the number of the target layers is more than 15,the positron yield does not increase significantly.