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

TL;DR

This paper discusses the development of microwave cavities designed for precise measurements of muonium hyperfine structure at J-PARC, enabling more accurate experiments with high-intensity proton beams.

Contribution

It introduces two microwave cavities optimized for muonium HFS measurements and evaluates systematic uncertainties using finite element method simulations.

Findings

Successful design of microwave cavities for muonium HFS measurement

Evaluation of systematic uncertainties from microwave field fluctuations

Preparation for high-precision measurements at J-PARC

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 at 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 systematic uncertainties from such a fluctuation of microwave fields and confirm the requirement of the microwave system, we use a microwave field distribution calculated from the finite element method.