System overview of liquid xenon calorimeter for the MEG experiment

MEG experiment aims to search for lepton flavor violating μ+→e+γμ+→e+γ decay with a sensitivity of 10-1310-13 branching ratio. To detect 52.8 MeV γ'sγ's, we have been developing a new photon detector with 900 L of liquid xenon viewed by 8462 in. photomultiplier tubes. Construction of the detector was finished in 2007, and the methods to keep liquid xenon stably were confirmed during the engineering run. In 2008, a calibration was done by using 55 MeV γ-raysγ-rays from π0π0 decays to estimate the detector performance. In autumn, MEG experiment has started taking physics data. The detector stability had been monitored by using 17.6 MeV γ'sγ's from Li(p,γ)BeLi(p,γ)Be reaction, etc. I will summarize here the detector preparation, operation, calibration, and monitoring methods, mainly concentrating on the hardware related things.