Surface muon production at J-PARC muon facility

The Muon Science Establishment (MUSE) at the Japan Proton Accelerator Research Complex (J-PARC) introduced an intense pulse surface muon beam for material science in late 2017. This development at MUSE enables researchers to utilize this highly controlled muon beam to study materials with enhanced accuracy and reliability. Our work aims to investigate proton transmission, surface muon production, contamination on a surface muon beam, and characteristics of the beam at surface muon beamline. Using Monte Carlo simulation programs, GEANT4 and G4beamline, to study interactions between the 3 GeV proton beam and the muon target. The results showed 95.43% proton transmission through the muon target. At the S-line entrance, the surface muon yield is 1.43 \(\varvec{\times }\) $\mathbf{\times }$ 10 \(^{-\text {7}}\) ${}^{-\text{7}}$ . The transverse positional distribution and phase space of the surface muon beam were also provided in this study. Our findings present an asymmetry along the horizontal axis and the beam entering the S-line is characterized as divergent, increasing in its transverse size. In summary, the primary proton beam loss at the muon target is 4.57%, which falls within the acceptable range for neutron facility operations that share the proton beam with the muon facility. The characteristics of the surface muon beam will be used for beam dynamic calculation and compared with the result considering the leakage magnetic fields from neighboring beamlines.