Neutron skyshine from Linac Coherent Light Source II 4 GeV electron beam operation at SLAC National Accelerator Laboratory can contribute to prompt radiation exposure to the public at distances far beyond the accelerator tunnel housing. One of the shielding design requirements at SLAC is that the annual dose to a member of the public is no more than 0.05 mSv y. This study uses Monte Carlo code FLUKA to simulate the generation of neutrons from 4 GeV electron beam losses on a thick copper target inside a generalized geometry of the Linac Coherent Light Source II Beam Transport Hall accelerator tunnel section. The effective dose from neutron skyshine was characterized as a function of both distance from the tunnel wall (up to 1 km away) and angle relative to the beam direction (between 0° and 180°). This new methodology for evaluating neutron skyshine dose is applicable to high-energy GeV-range electron accelerator facilities both at SLAC and elsewhere.

中文翻译：

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通过加速器装置评估天照：取决于距离和角度

SLAC国家加速器实验室的Linac相干光源II 4 GeV电子束操作产生的中子天光可以促使辐射在远离加速器通道的地方迅速暴露给公众。SLAC的屏蔽设计要求之一是，对公众的年度剂量不得超过0.05 mSv y。这项研究使用Monte Carlo代码FLUKA来模拟直线加速器相干光源II束传输大厅加速器隧道截面的广义几何形状内厚铜靶上4 GeV电子束损失产生的中子。来自中子天窗的有效剂量的特征是距隧道壁的距离（最远1 km）和相对于射束方向的角度（0°至180°之间）的函数。