Title: First operation of the FAMU experiment at the RIKEN-RAL high intensity muon beam facility Show Chinese title

Title: FAMU实验在RIKEN-RAL高强μ子束流设施中的首次操作

Abstract: The FAMU experiment, supported and funded by the Italian Institute of Nuclear Physics (INFN) and by the Science and Technology Facilities Council (STFC), aims to perform the first measurement of the ground-state hyperfine splitting (1S-hfs) of muonic hydrogen ($\mu H$). This quantity is highly sensitive to the proton's Zemach radius $R_Z$. An experimental determination of $R_Z$ provides significant constraints on the parametrization of the proton form factors as well as on theoretical models describing the proton's electromagnetic structure. Following years of technological and methodological development, the FAMU experiment began operations in 2023 at Port 1 of the RIKEN-RAL muon beam line at the ISIS Neutron and Muon Source facility (Didcot, UK). In this paper, we first describe the unique detection technique employed by FAMU to determine the 1S-hfs of muonic hydrogen, followed by a detailed presentation of the final experimental layout. Finally, we report the first outcome from the 2023 commissioning run and from the initial physics runs performed in 2023 and 2024. Show Chinese abstract

Abstract: 由意大利核物理研究所（INFN）和科学技术设施理事会（STFC）支持和资助的FAMU实验，旨在对缪子氢的基态超精细分裂（1S-hfs）进行首次测量（$\mu H$）。该量对质子的泽马半径（$R_Z$）非常敏感。对$R_Z$的实验测定为质子形式因子的参数化以及描述质子电磁结构的理论模型提供了重要的约束。在多年的技术和方法发展之后，FAMU实验于2023年在ISIS中子和缪子源设施（英国迪克特）的RIKEN-RAL缪子束流线的端口1开始运行。在本文中，我们首先描述FAMU用于确定缪子氢的1S-hfs的独特探测技术，随后详细介绍了最终的实验布局。最后，我们报告了2023年调试运行以及2023年和2024年进行的初始物理运行的首次结果。