Muon source development for the J-PARC muon g-2/EDM experiment
The J-PARC muon g-2/EDM experiment intends to measure the muon anomalous magnetic moment (a_μ = (g-2)/2) and to search for the muon electric dipole moment (μEDM, d_μ) at the world’s best sensitivity using an innovative technique. According to the recent theoretical studies and Fermilab E989 measurements, the long-standing deviation between the a_μ prediction and measurement has been updated to be at a significance of 4.2 standard deviations. The a_μ is certainly one of the best probes for new physics beyond the standard model of particle physics. The d_μ is predicted to be too small for the present experimental sensitivity and, therefore, is another probe for the enhancement due to a new physics contribution. Due to the EDM nature, furthermore, such a contribution would have a new CP-violating source.
The innovative technique of a small-emittance muon beam provides a very different experimental approach from the precedent and on-going measurements, where the dominant experimental conditions and apparatus were inherited, making the J-PARC measurement more valuable. The muon source of such a beam is responsible for generating ultra-slow muons, which are thermalized at room temperature and have a small position-momentum phase-space (“emittance”). The J-PARC muon g-2/EDM experiment is under development/construction and is planned to be launched in the fiscal year of 2025. In this talk, a brief overview of the experiment and the status of the muon source development will be presented.