A Novel Experiment Searching for the Lepton Flavor Violating Decay \mu \rightarrow eee
D. Wiedner, Heiko Christian Augustin, S. Bachmann, Niklaus Berger, M. Kiehn, Ivan Peric, Ann-Kathrin Perrevoort, André Schöning · 2013
The Mu3e experiment is aimed at the measurement or exclusion of the charged lepton flavor violating decay µ + → e + e -e + with a branching ratio (BR) sensitivity of 10 -16 .The decay µ + → e + e -e + is strongly suppressed in the standard model with a BR of 10 -50 , but enhanced to observable levels in many models for new physics.To reach this sensitivity the Mu3e detector has to have high rate capabilities of >10 9 events per second and excellent momentum, spacial and time resolution to suppress background.Two double layers of pixel sensors around a large stopping target in a 1 T field allow for precise vertex and momentum determination.As the decay electrons have a low momentum (≤ 53 MeV/c), an extremely light pixel detector design with X/X 0 ≤ 0.1 % per layer will be realized with the help of high voltage monolithic active pixel sensors (HV-MAPS) thinned to 50 µm in order to minimize the effects of multiple scattering.The detector is complemented by two timing systems, which allow to suppress combinatorial background even at high muon stop rates > 1 GHz.