The Timing Counter of the MEG experiment: Design and commissioning

In the MEG experiment, the Timing Counter detector is designed to deliver trigger information and to accurately measure the time of flight of the e + for searching the exotic decay μ → e + γ . It consists of two sectors up and down stream the decay target. Each sector is made of two layers: scintillating fibers read by APD for trigger and track reconstruction in the inner side, scintillating bars with PMT readout for trigger and time measurement in the outer one. The design criteria and fabrication methods of the detector and electronics, the integration in the MEG apparatus and its performance in the qualification test are presented.