FOR 5199:  Searching for charged lepton flavour violation with the Mu3e experiment

• Subject Area: Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 443478861

The Mu3e experiment searches for the charged lepton flavour violating decay μ→eee, in its first phase aiming for a single event sensitivity (SES) of BR(μ→eee) ≈ 2-3 ∙1015, corresponding to a factor 200 improvement compared to the existing bound. A novel detector concept using ultra-thin high-voltage monolithic active pixel sensors, scintillating fibers and tiles for accurate timing measurements and a triggerless data acquisition combined with online reconstruction using graphics cards allows to reach this sensitivity goal. The experiment is currently under construction at the Paul Scherrer Institute (PSI) in Switzerland as a collaboration of German, Swiss and UK institutes. The German institutes play key roles in the experiment by providing the pixel sensors and building the vertex tracker, providing the timing chip and building the scintillating tile detector and by providing the data acquisition and filter farm as well as by making key contributions to the simulation, reconstruction and analysis software. In the second funding period, the detector will be assembled and commissioned, allowing for a first data taking and a competitive search for μ→eee decays. PSI will build a new high-intensity muon beamline starting in 2027. This will provide around 2∙109 muons/s to Mu3e and thus allows reaching the ultimate sensitivity of O(10-16). A focused R&D program tackles the challenges posed by the 20 time higher rates in the second phase of the experiment by developing pixel sensors with a better time resolution and an ultra-fast silicon pixel detector to replace the scintillating fibre detector as well as by fast data transfer out of the detector and advanced reconstruction algorithms.

• DFG Programme: Research Units

Projects

• Coordination Funds (Applicant Schöning, André )
• Searching for charged lepton flavour violation with the Mu3e experiment -- Data Acquisition (Applicant Berger, Niklaus )
• Searching for charged lepton flavour violation with the Mu3e experiment -- Pixel Sensor (Applicant Peric, Ivan )
• Searching for charged lepton flavour violation with the Mu3e experiment - Pixel Tracking Detector (Applicant Schöning, André )
• Searching for charged lepton flavour violation with the Mu3e experiment - Scintillating Tile Detector (Applicant Schultz-Coulon, Hans-Christian )

• Spokesperson: Professor Dr. André Schöning