Comparison of direct and indirect positron-generation by an ultra-intense femtosecond laser
Comparison of direct and indirect positron-generation by an ultra-intense femtosecond laser
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DOI：
10.1063/1.4826219
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发表时间：
2013-10
影响因子：
2.2
通讯作者：
Yonghong Yan;Bo Zhang;Yuchi Wu;K. Dong;Yuqiu Gu;Z. Yao
中科院分区：
文献类型：
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作者：
Yonghong Yan;Bo Zhang;Yuchi Wu;K. Dong;Yuqiu Gu;Z. Yao
用二维胞内粒子模拟和蒙特卡罗模拟对超强飞秒激光产生的正电子束在直接方案和间接方案下的特性进行了广泛的比较。结果表明，间接方案产生的正电子束比直接方案产生的正电子束具有更高的产额(10{sup 10})、更高的温度(28.8 MeV)、更短的脉冲宽度(5ps)和更小的发散(8°)。此外，还发现间接方案的正电子/伽马比比直接方案高一个数量级，这表明在正电子探测中有较高的信噪比。然而，直接产生方法仍然有其独特的优势，即所谓的靶法向鞘加速，它可以产生可能用于某些特殊应用的准单能正电子束。
An extensive comparison of the properties of positron beams produced by an ultra-intense femtosecond laser in direct and indirect schemes has been performed with two-dimensional particle-in-cell and Monte Carlo simulations. It is shown that the positron beam generated in the indirect scheme has a higher yield (10{sup 10}), a higher temperature (28.8 MeV), a shorter pulse duration (5 ps), and a smaller divergence (8°) than in the direct case (10{sup 9} yield, 4.4 MeV temperature, 40 ps pulse duration, and 60° divergence). In addition, it was found that the positron/gamma ratio in the indirect scheme is one order of magnitude higher than that in the direct one, which represents a higher signal/noise ratio in positron detection. Nevertheless, the direct generation method still has its own unique advantage, the so-called target normal sheath acceleration, which can result in quasi-monoenergetic positron beams that may serve in some specialized applications.