paper

Technical design of the phase I Mu3e experiment

arXiv:2009.11690 · doi:10.1016/j.nima.2021.165679

Abstract

The Mu3e experiment aims to find or exclude the lepton flavour violating decay $I^¼ \to eee$ at branching fractions above $1 0^{- 16}$ . A first phase of the experiment using an existing beamline at the Paul Scherrer Institute (PSI) is designed to reach a single event sensitivity of $2 \cdot 1 0^{- 15}$ . We present an overview of all aspects of the technical design and expected performance of the phase~I Mu3e detector. The high rate of up to $1 0^{8}$ muon decays per second and the low momenta of the decay electrons and positrons pose a unique set of challenges, which we tackle using an ultra thin tracking detector based on high-voltage monolithic active pixel sensors combined with scintillating fibres and tiles for precise timing measurements.

117 pages. Minor corrections to the author list. Replaced with published version. Editor: Frank Meier Aeschbacher