Design, construction and performance of Dai Omega, a large solid-angle axial-focusing superconducting surface-muon channel

An intense surface-muon-producing channel “Dai Omega” was constructed at the KEK Muon science laboratory. Large-aperture superconducting coils are utilized to focus and transport muon beams of 30 MeV/c. A large solid-angle acceptance of 1 sr and axial-focusing beam transportation provide substantial performance enhancement over conventional surface muon channels that utilize quadrupole-magnet focusing. The worldʹs most intense pulsed surface muon beam of 2×104 μ+/pulse is achieved at KEK (500 MeV, 5 μA). Design, construction, and performance of Dai Omega as well as associated equipment are described in this paper.