Speaker
Malte Hildebrandt
(Paul Scherrer Institut)
Description
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.
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Primary author
Malte Hildebrandt
(Paul Scherrer Institut)
