Development and commissioning of the 30 ps time resolution MEG II pixelated Timing Detector

The MEG II experiment is designed to improve by an order of magnitude the sensitivity of $4.2\times 10^{-13}$ reached by MEG on the search for ${\mu }^{+}\to e^{+}\gamma$ decay. A pixelated Timing Counter (pTC) has been developed to improve the time resolution by measuring the positron time information independently with several counters. We constructed and installed the pTC and performed commissioning runs at the $\pi$E5 beam line at PSI. A resolution of 38.5 ps is obtained with commissioning run data.