Liquid xenon gamma ray detector for MEG

The MEG experiment searches for the rare muon decay μ + → e + γ , which is forbidden in the standard model. The detection of this muon decay is a probe for new physics beyond the standard model. In order to improve the sensitivity of the experiment, a liquid xenon detector is used for measuring energy, position and time of gamma rays. The detector consists of 800 l of liquid xenon and 846 photo-multiplier tubes. We have performed beam tests and evaluated resolutions by using a prototype.