Superconducting curved transport solenoid with dipole coils for charge selection of the muon beam

•Superconducting curved transport solenoid.•Muon charge selection by superimposed dipole field.•World strongest pulsed muon source. At the J-PARC Muon Science Facility (MUSE) the Super-Omega muon beamline is now under construction in the experimental hall No. 2 of the Materials and Life Science Facility building. Muons up to 45MeV/c will be extracted with a large acceptance solid angle to produce the world highest intensity pulsed muon beam. This beamline comprises three parts, a normal-conducting capture solenoid, a superconducting curved transport solenoid and an axial focusing solenoid. Since only solenoids are used, both surface μ+ and cloud μ− are extracted simultaneously. To accommodate future experiments that would only require either μ+ or μ− beam, two dipole coils located on the straight section of the curved solenoid provide the muon charge selection by directing one of the beam onto the solenoid inner-wall. The design parameters, the construction status and the initial beam commissioning are reported.