Design and Manufacture of a Superconducting Solenoid for D-Line of J-PARC Muon Facility

A superconducting solenoid for J-PARC muon facility was newly designed and manufactured. High Energy Accelerator Research Organization (KEK) has been operating the J-PARC Muon Science Establishment (MUSE) since 2008. Among its four muon beam lines, the decay muon line (D-Line) has been extracting and providing surface muons and positive decay muons up to a momentum of 50 MeV/c for various users, utilizing a superconducting solenoid. The D-Line as well as the other J-PARC facility suffered severe damages from the earthquake on March 11, 2011. It necessitated rebuilding of the damaged superconducting solenoid. New design parameter of the solenoid is as follows: length of solenoid: 6 m, diameter of warm bore: 0.2 m, magnetic field of bore center: 3.5 T, rated current: 415 A, superconducting wire: NbTi/Cu, quench protection: quench back heaters. The six-meter-long solenoid consists of twelve pieces of 0.5-meter-long superconducting coils. The entire solenoid is forced-indirectly cooled by supercritical helium flow. This report describes the design and manufacturing process of the newly built superconducting solenoid for D-Line of J-PARC muon facility.