基于SHINE的GeV级前向缪子分量的加速器缪子成像模拟研究
Simulation study of accelerator-based muography using the GeV-scale forward muon component at SHINE
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中文总结 AI 辅助
本研究通过Geant4模拟验证了利用SHINE设施3 GeV电子束产生的GeV级前向缪子进行定量缪子成像的可行性，在约6小时内累积3×10^5有效缪子事件即可实现高于0.9的结构相似性指数，且强度远超宇宙射线源。
中文摘要 AI 辅助
缪子成像利用缪子的穿透能力对大尺寸致密物体的内部进行成像，但宇宙射线源仅提供约1 {cm}^{-2} {min}^{-1}的通量且主要来自上方，限制了成像速度和可探测的几何结构。最近，利用激光尾场加速器已演示了电子驱动的缪子产生，但逐发间的波动阻碍了定量加速器缪子成像所需的系统性研究。利用Geant4蒙特卡洛模拟，我们对上海高重频X射线自由电子激光与极端光设施（SHINE）2号竖井的完整实验装置进行了建模，涵盖从3 GeV、50 pC、50 Hz调试电子束与缪子靶相互作用，经过25米束线结构和3米厚混凝土隔离墙的全过程。每束团约有0.28个有效重建单缪子事件，其穿过隔离墙后的剩余动能低于1.2 GeV，到达下游缪子成像测试区（约14 s^{-1}）。隔离墙吸收了大部分能量低于约1 GeV的带电本底粒子，而残余中子可通过其特征探测器能量沉积进行甄别。散射断层扫描模拟表明，在调试速率下约6小时内累积的3×10^{5}个有效缪子事件，可产生高于0.9的结构相似性指数，证明了利用SHINE电子驱动的GeV级前向缪子源进行定量加速器缪子成像的可行性。在8 GeV/50 kHz基准下，预计缪子强度超过5×10^{4} {\u03bc}/s，保守对应探测器处每束团约一个缪子。这比宇宙射线通量高出数个数量级，而SHINE的超导直线加速器为发展电子打靶缪子成像提供了稳定、可控的平台。
英文摘要
Muography exploits the penetrating power of muons to image the interior of large dense objects, but cosmic-ray sources provide only ~1 {cm}^{-2} {min}^{-1} predominantly from above, limiting imaging speed and accessible geometries. Electron-driven muon production has recently been demonstrated with laser-wakefield accelerators, but shot-to-shot fluctuations hinder systematic studies required for quantitative accelerator muography. Using Geant4 Monte Carlo simulations, we model the full experimental setup at Shaft 2 of the Shanghai High repetition rate XFEL and Extreme light facility (SHINE), from a 3 GeV, 50 pC, 50 Hz commissioning electron beam interacting with a muon target through 25 m of beamline structures and a 3 m-thick concrete isolation wall. Approximately 0.28 effective reconstructed single-muon events per bunch, with residual kinetic energies below 1.2 GeV after traversing the wall, reach the downstream muography test area (~14 s^{-1}). The wall absorbs most charged background particles below ~1 GeV, while residual neutrons can be discriminated by their characteristic detector energy deposition. Scattering-tomography simulations show that $3\times 10^{5}$ effective muon events, accumulated in approximately 6 h at the commissioning rate, yield a Structural Similarity Index above 0.9, demonstrating the feasibility of quantitative accelerator-based muography using SHINE's electron-driven GeV-scale forward muon source. At the 8 GeV/50 kHz benchmark, the projected muon intensity exceeds $5 \times 10^{4}$ μ/s, corresponding conservatively to approximately one muon per bunch at the detector. This exceeds the cosmic-ray flux by orders of magnitude, while SHINE's superconducting linac provides a stable, controlled platform for developing electron-on-target muography.
