Contribution Oral presentation
The LXe calorimeter and the pixelated timing counter in the MEG II experiment
The purpose of the MEG experiment is to look for a lepton flavor violating μ→eγ decay with an unprecedented sensitivity, and we set an upper limit of the branching ratio for this decay, 5.7×10⁻¹³ at 90% C.L. in 2013 which is twenty times more stringent limit than the previous experiment, MEGA. Since the sensitivity improvement of the MEG experiment was limited by the accidental background, we have considered the major detector upgrade. A proposal was submitted to PSI committee, and was approved by PSI in 2013, which aims for a sensitivity enhancement of one order of magnitude compared to the final MEG result. Here I will mainly introduce you two components of the MEG detector, a gamma-ray calorimeter with 900 l liquid xenon (LXe), and a pixelated timing counter. The LXe detector will be improved by increasing the granularity at the incident face, by replacing the current PMTs with a larger number of smaller photosensors (MPPC) and optimizing the photosensor layout also on the lateral faces. A new highly segmented, fast timing counter array will replace the old system to allow improved timing resolution capabilities.