The muon to electron conversion process and the Mu2e experiment at Fermilab

Abstract

The Mu2e experiment at Fermi National Accelerator Laboratory will search for the Charged Lepton Flavour Violating (CLFV) neutrino-less coherent conversion of a muon into an electron in the eld of a nucleus with a single event sensitivity of 3 ·10−17, which is an improvement of four order of magnitude over the existing limits. The muon conversion probes new physics at a scale that cannot be reached with direct searches at present or planned colliders and complements similar searches for CLFV performed by the MEG-II experiment at Paul Scherrer Institut. In this paper, we report on the Mu2e physics motivations, the design of the muon beamline and the detectors employed by the experiment, which include a tracking spectrometer, a calorimeter and a cosmic ray veto. Mu2e is currently being constructed at the Fermilab Muon Campus and is expected to begin data taking in 2025 (Run 1) with a reduced average beam intensity. Run 1 will continue for two years. After a shutdown for the upgrade of Fermilab accelerator complex, Mu2e data taking will be resumed at full beam intensity in 2029 (Run 2).