强激光与固体靶相互作用产生的硬X射线已被证实为一种新的电离辐射源,其辐射防护问题引起国内外相关领域的广泛关注。为了便于开展这类电离辐射源的屏蔽设计,研究了强激光打靶所致硬X射线在常用屏蔽材料中的剂量衰减曲线和十值层(TVL)。利用蒙特卡罗程序FLUKA建立了强激光打靶所致硬X射线的屏蔽计算模型,开发了专门的统计程序,解决了屏蔽层之间由于粒子反散射造成的重复统计问题,使得可以通过一次模拟得到不同屏蔽厚度下的光子剂量。计算结果表明: 当电子温度为0.5~10 MeV时,X射线在混凝土中的十值层从24 cm到56 cm不等。其中X射线的十值层会随着电子温度的增加而增加,并逐渐趋于饱和。而对于铅屏蔽,除了第一个十值层(TVL1)外,平衡十值层随电子温度的变化较小,在4.7~5.4 cm范围内。另外,当电子温度较高时,探测器到屏蔽体的距离不同会使得TVL1值存在明显的差异。

Previous experiments have shown that high-intensity laser interaction with a solid target can be regarded as a new ionizing radiation source. The radioprotection issue attracts a growing concern worldwide. In order to effectively control the radiological hazard from the X-ray produced by high-intensity laser interaction with solid targets, transmission curves and tenth-value layer (TVL) values in common shielding materials are studied. In this paper, a shielding calculation model was established using Monte Carlo code FLUKA. A specialized routine was developed to solve the problem of repeated scoring caused by the backscattering of particles. Transimitted doses were then obtained for various shielding thicknesses in a single run. The results show that for electron temperatures of 0.5-10 MeV, the TVL value in concrete increases with the electron temperature and ranges from 24 to 56 cm; In lead, except for the first TVL, the equilibrium TVL value shows less correlation with the electron temperature and ranges from 4.7-5.4 cm. In addition, for the high electron temperature, the first TVL value is significantly affected by the distance between the shielding material and the detector.