New and Optimized Magnetization Scheme for the Baby Magnetized Iron Neutrino Detector at J-PARC

The Baby-MIND (magnetized iron neutrino detector) collaboration is building a muon detector to be installed downstream of the WAGASCI experiment at J-PARC (Japan). Due to the challenging timeline and space constraints for the installation in the ND280 pit, an innovative magnetization scheme has been developed for the iron plates. The magnetization scheme optimizes flux return for minimum stray field and operating current, while maximizing the useful tracking area with $B > 1.5$ T. The 33 iron plates of the detector are individually magnetized by coils wound on their surface by “sewing” an aluminum conductor through slits cut in the plates. In this paper, we present the details of the magnetization scheme and coil winding procedure as well as the results of magnetization tests performed on a prototype module and the first eighteen detector plates.