XG-Ⅲ装置ps激光束线所致感生放射性评估研究

Study on Residual Radioactivity Evaluation of ps Laser Beam Line of XG-Ⅲ Device

利用PIC与蒙特卡罗模拟方法对XG-Ⅲ装置在ps激光束线驱动的X射线源和中子源等多种工作模式下进行了剂量学评估,使用PIC模拟确定了高能电子源项后,将其作为蒙特卡罗软件FLUKA的输入数据,通过模拟计算得到了不同靶材在实验结束后不同时刻的感生放射性核素活度及在靶周围所致的剂量。模拟结果表明,对于激光驱动的轫致辐射X射线源,在每次打靶完成并冷却10 min后,在距靶表面1 cm处的感生放射性剂量率约为4 mSv/h,而在距靶表面30 cm处的感生放射性剂量率则已降低到15μSv/h。对于激光驱动的光核反应产生的光中子源,冷却10 min后在距靶表面1 cm处的感生放射性剂量率小于10μSv/h。除了靶的材料,靶厚度也会对靶周围的感生放射性剂量率变化情况产生影响,因此有必要在不同的照射环境下,针对不同的靶材及靶厚采取不同的辐射防护方案。本文研究结果可为超短超强激光设施的辐射风险分析及辐射防护工作提供相关参考。

The PIC and Monte Carlo simulation methods were used to evaluate the dose of X-ray source and neutron source driven by the ps laser beam line of the XG-Ⅲ device. After using PIC to determine the high-energy electron source term, it was used as input data of Monte Carlo software FLUKA to obtain the residual radioactivity and the residual dose around different targets at different time after the experiment. The simulation results show that for the laser-driven bremsstrahlung X-ray source, after the experiment is completed and cooled for 10 min, the residual dose rate at 1 cm from the target surface is about 4 mSv/h, and 15 μSv/h at 30 cm from target surface. For the photo-neutron source generated by the laser-driven photonuclear reaction, the residual dose rate at 1 cm from the target surface is less than 10 μSv/h after the experiment is completed and cooled for 10 min. In addition to the type of target material, the variation of the residual dose rate around the target will also be affected by the thickness of the target. Therefore, in different irradiation environments, it is necessary to adopt different radiation protection schemes for targets with different materials and thicknesses. The results of this study can provide relevant reference for radiation risk analysis of protective measures of ultra-short ultra-intense laser facility.