Yamaguchi, Hiroshi; Sasaki, Ken-ichi; Tanaka, Toya; Abe, Mitsushi; Flay, David; Kawall, David; Mibe, Tsutomu; Seo, Shun; Shimomura, Koichiro; Ueno, Yasuhiro; Winter, Peter
Muonium spectroscopy experiment using microwave and J-PARC E34 (J-PARC muon g-2/EDM) experiments aim to measure the hyperfine structure of muonium and anomalous magnetic moment of muon, respectively. Both experiments require homogeneous magnetic fields better than 1 ppm. Therefore, we developed a standard probe to calibrate field measurement probes, with a resolution of 1.92±0.18 ppb. Moreover, a shift of the nuclear magnetic resonance frequency of the standard probe was also evaluated, and a total uncertainty of the shift is ±17.7 ppb.