The new trigger and data acquisition system for LFV searches in the MEG II experiment

The MEG II experiment aims at a factor 10 improvement in the branching ratio limit of the muon to electron plus photon decay; it follows the path traced by its previous phase (known as MEG I) which already produced the world best upper limit of <= 4.2 10^-13 @ 90% C.L. The new experimental apparatus is currently in its commissioning phase at Paul Scherrer Institute in Switzerland. In this thesis a novel Trigger and Data acquisition (TDAQ) system, named WaveDAQ, is described with the goal of fulfilling the requirements of the experiment upgrade, the most stringent one being the readout of ~8000 channels at GHz speeds. The single event size will be therefore in the order of 12 MB without any compression or zero-supperession, thus a very selective yet efficient online event selection needs to be operated to maintain the throughput at a reasonable level (< 24 Hz). The first results of the new apparatus in 2018 and 2019 pre-engineering run are reported validating the full design of the TDAQ system toward its final production in 2020. Having the capabilities to increase the the event speed in dedicated runs up to few 100 Hz, exotic Lepton Flavor Violating channels in reach of MEG II are presented and sensitivity on the muon to electron plus invisible was studied. Results show a very huge effect of momentum scale uncertainty on the measurement which needs to be fixed below the 5 keV/c level in order for MEG II to be competitive with current limits of ~10^-5 by the TWIST collaboration.