Characterization and optimization of ultra slow muon beam at J-PARC/MUSE: A simulation study

We have been developing an ultra slow muon microscope on the Super-omega muon beamline, called U-line, at the Muon Science Establishment (MUSE), Japan Proton Accelerator Research Complex (J-PARC), Japan. This development is expected to aid studies on nanoscience and three-dimensional visualization of small samples. During commissioning of the ultra slow muon beam, we performed Monte Carlo simulations, the results of which pointed out the significant effect of a stray magnetic field at the muonium chamber on the beam profile at sample position. To minimize this effect, we steered the beam using imbalance tuning of electric quadrupoles. This paper presents the simulation study of beam transportation, optimization, and characterization in terms of beam size, time, and energy distribution at sample position in one of the experimental areas, namely, U1A.