紧凑型超快强激光驱动晶体基γ辐射、正电子和中子源

中文摘要 AI 辅助

紧凑型强γ射线、正电子和中子源可以将辐射和粒子束能力带到小型大学级实验室，否则这些实验室将依赖大型加速器设施。在这里，我们提出并模拟了一种紧凑型激光驱动源，该源将激光等离子体尾场加速（LWFA）与取向晶体靶相结合，以增强相对论电子束向高能光子和次级粒子的转换。沿主要晶体学方向排列的电子经历相干相互作用，包括沟道辐射和相干轫致辐射，与非晶靶相比，产生显著增强的光子发射。此外，发射辐射的强角-谱相关性使得能够生成具有减小谱带宽的准直γ射线束。因此，晶体增强发射可以提高粒子产生效率，即通过γ转换为电子-正电子对产生正电子，以及通过光核反应产生中子。使用Geant4模拟，我们研究了300 MeV、1 GeV和3 GeV的电子能量与取向钨晶体的相互作用。晶体取向使γ射线、正电子和中子产额提高高达约2倍，对于200 pC电子束（持续时间为几飞秒），达到约10^24 γ/s、约10^23 e^+/s和约10^21中子/s的产生速率。准直γ射线亮度达到约10^24 γ/s/mm^2/mrad^2/0.1%BW，与随机晶体取向相比增强6-8倍。我们进一步展示了通过薄金刚石晶体中的相干轫致辐射实现可调谐准单色辐射，达到约3.5×10^20 γ/s/mm^2/mrad^2/0.1%BW的亮度。此外，我们讨论了所提出技术的潜在应用。

英文摘要

Compact sources of intense $γ$-rays, positrons and neutrons can bring radiation and particle-beam capabilities to small university-scale laboratories that would otherwise rely on large accelerator facilities. Here we propose and simulate a compact, laser-driven source that combines laser plasma wakefield acceleration (LWFA) with oriented crystalline targets to enhance the conversion of relativistic electron beams into high-energy photons and secondary particles. Electrons aligned with major crystallographic directions undergo coherent interactions, including channeling radiation and coherent bremsstrahlung, producing substantially enhanced photon emission compared with amorphous targets. Moreover, the strong angular-spectral correlation of the emitted radiation enables the generation of collimated $γ$-ray beams with reduced spectral bandwidth. Consequently, crystal-enhanced emission can increase particle-production efficiency, namely that of positrons through $γ$ conversion into electron-positron pairs and of neutrons through photonuclear reactions. Using Geant4 simulations, we investigate electron energies of 300 MeV, 1 GeV and 3 GeV interacting with an oriented tungsten crystal. Crystal orientation increases the $γ$-ray, positron and neutron yields by up to a factor of $\sim2$, reaching production rates of $\sim10^{24}γ/s$, $\sim10^{23}e^+/s$ and $\sim10^{21}neutrons/s$ for a 200 pC electron bunch with a duration of a few fs. The collimated $γ$-ray brightness reaches $\sim10^{24}γ/s/mm^2/mrad^2/0.1\%BW$, with an enhancement of 6-8 compared with random crystal alignment. We further demonstrate tunable quasi-monochromatic radiation through coherent bremsstrahlung in a thin diamond crystal, reaching a brilliance of $\sim3.5\cdot10^{20}γ/s/mm^2/mrad^2/0.1\%BW$. Furthermore, we discuss the potential applications of the technique proposed.

发表机构

• INFN Ferrara Division（意大利国家核物理研究所费拉拉分部）
• Ulsan National Institute of Science and Technology（蔚山科学技术院）
• Gwangju Institute of Science and Technology, Institute for Basic Science（光州科学技术研究院基础科学研究院）
• Université Paris-Saclay, CNRS/IN2P3, IJCLab（巴黎萨克雷大学，法国国家科学研究中心/法国国家原子能研究所）

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