The COMET Experiment to Search for 𝜇-e Conversion at J-PARC

The COMET experiment at J-PARC is designed to search for muon-to-electron (𝜇-e) conversion in aluminium atoms with unprecedented sensitivity, aiming to uncover physics beyond the Standard Model (BSM). By employing a two-phase approach, the experiment targets single-event sensitivities of 3 × 10⁻¹⁵ in Phase-I and 10⁻¹⁷ in Phase-II. The experimental setup utilises an 8 GeV bunched slow-extraction proton beam from the J-PARC Main Ring, which is transported through the dedicated beamline to the experimental facility. Superconducting solenoidal magnets efficiently collect and transport low-momentum muons to the stopping target. A variety of detector systems are being developed to measure signal electrons with high precision while suppressing dominant backgrounds. Preliminary studies, including Phase-𝛼 commissioning, have validated critical detector and beamline components. The experiment is planned to begin with low-intensity beam commissioning, with subsequent data collection focusing on the 𝜇-e conversion process.