NSF-GACR: Study of Gamma-Ray Generation in High-Intensity Laser-Plasma Interactions at ELI Beamlines

该项目将探索利用超高强度激光有效产生伽马射线。先进光源的发展促进了许多学科的科学技术的重大进步。下一个前沿领域是高效伽马射线的来源——其能量比典型的x射线高出数千倍。这些极端能量的光可用于基础研究，例如物质-反物质的产生和对天体物理多信使源的了解，以及在核材料探测、核废料分析和医疗同位素生产方面的应用。该项目的目的是在捷克共和国的极端光基础设施光束线（ELI-Beamlines）设施中演示使用超高强度激光器有效地产生伽马射线。这项合作由美国国家科学基金会和捷克科学基金会（GACR）之间的合作伙伴关系实现，结合了加州大学圣地亚哥分校所需的理论专业知识，ELI-Beamlines的实验专业知识和通用原子公司的目标制造专业知识。除了研究生培训，该项目还将为来自代表性不足群体的本科生提供专门的暑期实习机会。发射比可见光高100万倍的高能光子，将通过在高密度等离子体中驱动一个千兆高斯的准静态方位磁场来实现，该等离子体被超高强度激光脉冲变得透明。等离子体电子在将激光能量转换成密集的高能伽马射线束的过程中起着中介作用。限制的方位磁场有利于电子从激光中获得能量，而磁场内的电子偏转使电子向激光传播方向发射MeV伽马射线。极强的磁场强度和高电子能量保证了伽马射线发射的高效率。实验将在捷克共和国的ELI-Beamlines激光设备上进行。这些激光器达到超高目标强度的能力是达到理想状态的关键。实验将利用低质量泡沫靶产生致密等离子体，其电子密度远高于经典的截止密度，但低于实验中使用的激光强度的相对论调整截止密度。这种目标密度的选择使激光能够通过等离子体传播，同时也提供了MeV光子的有效产生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will explore efficient gamma-ray generation using ultra-high-intensity lasers. The development of advanced light sources has contributed to significant progress in science and technology across many disciplines. The next frontier are sources of efficient gamma-rays – whose energies are thousands of times higher than those of typical x-rays. Light at these extreme energies can be used in fundamental studies, such as matter-antimatter production and understanding of astrophysical multi-messenger sources, and in applications to nuclear material detection, nuclear waste analysis, and medical isotope production. The aim of this project is to demonstrate efficient gamma-ray generation using ultra-high-intensity lasers at the Extreme Light Infrastructure Beamlines (ELI-Beamlines) facility in the Czech Republic. This collaboration, enabled by the partnership between NSF and the Czech Science Foundation (GACR), combines the required theoretical expertise from UCSD, experimental expertise from ELI-Beamlines, and target fabrication expertise from General Atomics. In addition to graduate student training, the project will also provide dedicated summer internships to undergraduate students from underrepresented groups. The emission of high-energy photons, a million times higher than visible-light, will be achieved by driving a multi-GigaGauss quasi-static azimuthal magnetic field inside a dense plasma that is rendered transparent by an ultra-high-intensity laser pulse. Plasma electrons serve as a mediator in the conversion of laser energy into a dense beam of energetic gamma-rays. The confining azimuthal magnetic field facilitates electron energy gain from the laser, while the electron deflections within the magnetic field cause the electrons to emit MeV gamma-rays in the direction of laser propagation. The extreme magnetic field strength and high electron energy ensure high efficiency of gamma-ray emission. The experiments will be performed at the ELI-Beamlines laser facility in the Czech Republic. The ability of these lasers to reach ultra-high on-target intensity is the key to accessing the desired regime. The experiments will utilize low-mass foam targets to produce a dense plasma whose electron density is well above the classical cutoff density, but below the relativistically adjusted cutoff density for the laser intensities used in the experiments. This choice of target density enables laser propagation through the plasma while also providing efficient generation of MeV photons.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.