Development of the muon beam monitor for the T2K Long Baseline Neutrino Oscillation Experiment

We have developed the muon monitor for the T2K experiment. The muon monitor measures the profile of muons produced with neutrinos and provides real-time information of the neutrino beam. The monitor system consists of arrays of ionization chambers and solid state pad detectors. We conducted a beam test with an electron beam and a long term test at the NuMI beam line in FNAL. The prototype detectors worked stably for more than a half year in a “real” neutrino beam line. Based on the results, we finalized the design and produced the real muon monitor system.