11-15 February 2013
Vienna University of Technology
Europe/Vienna timezone

Performance of the low-mass drift chamber system of the MEG experiment

Not scheduled
Vienna University of Technology

Vienna University of Technology

Gußhausstraße 25-29, 1040 Wien (Vienna), Austria
Board: 28
Poster Gaseous Detectors


Malte Hildebrandt (Paul Scherrer Institut)


The MEG experiment searches for the lepton flavour violating decay mue → e + gamma and is located at the Paul Scherrer Institut (PSI) in Switzerland. The analysis of the combined data sample from 2009 and 2010 gives an upper limit of 2.4•10-12 (90% C.L.) on the branching ratio which is the most stringent limit up to date. The drift chamber system is designed to ensure precision measurements of 52.8 MeV/c positrons. The system consists of 16 drift chamber modules and is part of the innovative positron spectrometer of the MEG experiment. The chamber construction is a low-mass construction in order to reduce multiple scattering and therefore minimize effects on tracking resolution in the sensitive area. The total amount of material sums up to a radiation length of only 0.026 % per module and in average of only 0.2 % along the positron trajectory. To reach the required spatial resolution the method of charge division on the anode wires is used in combination with cathode Vernier pattern readout. A single hit resolution of 680 micron was achieved in axial and on average of 230 micron in transverse direction. The back tracking capability of the positron spectrometer allows a vertex resolution at the muon stopping target of ~7 mrad in phi and ~11 mrad in theta, respectively, corresponding to a resolution of ~1.5 mm for the decay vertex coordinates. The momentum resolution of 0.6 % was determined by using the high momentum edge of the Michel positron spectrum.
quote your primary experiment MEG

Primary author

Malte Hildebrandt (Paul Scherrer Institut)

Presentation Materials