E-320 experiment at FACET-II

本提案旨在支持贝尔法斯特女王大学的Gianluca Sarri博士和他的博士生Niall Cavanagh先生参与斯坦福直线加速器（SLAC） FACET-II光束线的E-320实验活动。该提案的研究人员是世界领先的大学和研究机构的国际合作的核心成员，包括普林斯顿大学，斯坦福大学，巴黎综合理工学院，马克斯普朗克核物理研究所和加州大学洛杉矶分校，最近在竞争激烈的环境中获得了FACET-II的一系列突破性强场量子电动力学（SFQED）实验的光束时间。简而言之，实验旨在研究FACET-II加速器提供的13 GeV电子束在通过已安装并运行的20 TW激光系统焦点时的动力学。峰值强度超过1 × 1020 Wcm^-2是可以实现的，这使得在电子的剩余框架中，峰值电场达到施温格场或QED临界场的70%。这个值大大超过了上世纪90年代末在SLAC获得的结果，也超过了最近由PI和合作者在英国中央激光设施使用Gemini激光器获得的结果。我们计划进一步推进先前的工作，通过进行精确的测量和收集广泛的数据集，以提供足够的统计数据来详细研究SFQED中的标志性现象，如量子辐射反应，强非线性康普顿散射和对产生。收集的数据将揭示当前高功率激光的强度前沿，允许人们不仅测试目前在这种物理制度中使用的数值和分析模型，而且还优化实验技术，为下一代超强激光设施的操作。

The present proposal is intended to support the participation of Dr. Gianluca Sarri and his PhD student, Mr. Niall Cavanagh, of The Queen's University of Belfast to the experimental campaign E-320 at the FACET-II beamline of the Stanford Linear Accelerator (SLAC). The investigator of this proposal is a central member of an international collaboration of world-leading Universities and research institutes, including Princeton, Stanford, Ecole Polytechnique, the Max-Planck institute for Nuclear Physics, and UCLA that recently was awarded, in an extremely competitive environment, beam time at FACET-II for a series of ground-breaking experiments on Strong-Field Quantum ElectroDynamics (SFQED). In a nutshell, the experiments aim at studying the dynamics of the 13 GeV electron beam provided by the FACET-II accelerator as it propagates through the focus of a 20 TW laser system, already installed and operational. Peak intensities exceeding 1x1020 Wcm^-2 can be realistically achieved, allowing to reach a peak electric field, in the rest frame of the electrons, of the order of 70% of the Schwinger field, or critical field of QED. This value significantly exceeds what previously obtained at SLAC in the late 90s and, more recently, by the PI and collaborators using the Gemini laser at the Central Laser Facility in the UK. We plan to further advance previous work by performing precision measurements and collecting extensive data sets to provide sufficient statistics to study in detail iconic phenomena in SFQED, such as quantum radiation reaction, strongly non-linear Compton scattering, and pair production. The collected data will shed light at the current intensity frontier of high-power lasers, allowing one not only to test numerical and analytical models currently used in this physical regime, but also to optimise experimental techniques for the operation of the next generation of ultra-intense laser facilities.