Development of microwave cavities for measurement of muonium hyperfine structure at J-PARC

• Published in: Progress of theoretical and experimental physics Vol. 2021; no. 5
• Main Authors: Tanaka, K S, Iwasaki, M, Kamigaito, O, Kanda, S, Kawamura, N, Matsuda, Y, Mibe, T, Nishimura, S, Saito, N, Sakamoto, N, Seo, S, Shimomura, K, Strasser, P, Suda, K, Tanaka, T, Torii, H A, Toyoda, A, Ueno, Y, Yoshida, M
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01.05.2021
• Subjects: C31; C07
• ISSN: 2050-3911; 2050-3911
• DOI: 10.1093/ptep/ptab047

Abstract The MuSEUM collaboration is planning measurements of the ground-state hyperfine structure (HFS) of muonium at the Japan Proton Accelerator Research Complex (J-PARC), Materials and Life Science Experimental Facility. The high-intensity beam that will soon be available, the H-line, allows for more precise measurements by one order of magnitude. We plan to conduct two staged measurements. First, we will measure the Mu-HFS in a near-zero magnetic field, and thereafter we will measure it in a strong magnetic field. We have developed two microwave cavities for this purpose. Furthermore, we evaluated the systematic uncertainties from such a fluctuation of microwave fields and confirmed the requirements for the microwave system; we use a microwave field distribution calculated with the finite element method.