Aachen 2019 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 42: Experimentelle Methoden I
T 42.1: Gruppenbericht
Dienstag, 26. März 2019, 16:00–16:20, ST 1
Track reconstruction for the Mu3e experiment — •Alexandr Kozlinskiy for the Mu3e collaboration — Institut für Kernphysik, Johannes Gutenberg-Universität Mainz
The Mu3e experiment is designed to search for the lepton flavour violating decay µ+ → e+e−e+. The aim of the experiment is to reach a branching ratio sensitivity of 10−16. In a first phase the experiment will be performed at an existing beam line providing 108 muons per second at the Paul-Scherrer Institute (Switzerland) which will allow to reach a sensitivity for the branching fraction 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 µm thin silicon pixel sensors. The high granularity of the pixel detector with a pixel size of 80 × 80 µm 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. To deal with such a high occupancy and combinatorics 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.