Speaker
Description
The Mu3e experiment is designed to search for the lepton flavour
violating decay $\mu^+ \rightarrow e^+e^-e^+$.
The aim of the experiment is to reach a branching ratio sensitivity of $10^{-16}$.
At first phase the experiment will be performed at existing beam line
providing $10^8$ muons per second at the Paul-Scherrer Institute (Switzerland)
which will allow to reach sensitivity of $10^{-15}$.
The muons with a momentum of about 28 MeV/c are stopped and decay at
rest on a target.
The decay products (positrons and electrons) with energies below 53 MeV
are measured by a tracking detector consisting of two double layers of
50 $\mu$m thin silicon pixel sensors.
The high granularity of pixel detector with a pixel size of $80\times80$ $\mu$m
allows for a precise track reconstruction in the high occupancy environment of
the Mu3e experiment reaching 100 tracks per reconstruction frame of
50 ns in the final phase of experiment.
The Mu3e track reconstruction uses a novel fit algorithm that in
the simplest case takes into account only the multiple scattering, which allows
fast online tracking on a GPU based filter farm.
The implementation of the 3-dimensional multiple scattering fit based on hit
triplets is described.
The extension of the fit that takes into account energy losses and pixel size
is used for offline track reconstruction.
The algorithm and performance of the offline track reconstruction based on
a full Geant4 simulation of the Mu3e detector are presented.
