Development of a polarization monitor for the J-PARC muon g − 2/EDM experiment

Abstract

In the J-PARC Muon $g-2$/EDM experiment, the Polarization Monitor plays a crucial role in assessing the quality of muon beams by measuring the spin polarization of muons in the muonium production chamber. This is achieved through analyzing the asymmetry in muon decay, which serves as an indicator of beam quality. The development of this detector system is segmented into three distinct phases. The initial two phases have undergone validation using atmospheric muons. A significant aspect of Phase 1 is the simulation study, which, when integrated with energy deposition calibration derived from experimental data, effectively minimizes background noise caused by muon decays within the scintillator. Furthermore, the construction of the Phase 1 apparatus has been completed, and preliminary data collection has revealed a notable difference in asymmetry between polarized and unpolarized muons. This finding is instrumental in advancing the development of Phases 2 and 3 of the detector system.