Speaker
Hajime Nishiguchi
(Uni Tokyo)
Description
We have been developing an innovative spectrometer for the MEG
experiment at the Paul Scherrer Institute (PSI) in Switzerland. This
experiment searches for a lepton flavour violating decay μ + → e+ γ with a
sensitivity of 10 −13 in order to explore the region predicted by
supersymmetric extensions of the standard model. The MEG positron
spectrometer consists of a superconducting solenoidal magnet, a drift
chamber system, and a time measuring counter system. In the MEG
experiment, the spectrometer must cope stably with very high muon
stopping rate up to 10 8 sec−1. Our special superconducting solenoidal
magnet which has a highly graded magnetic field allows a background of
lower energy Michel positrons to be swept away more effectively from the
fiducial tracking volume. Furthermore, the ultimately low-mass drift
chambers, which cause much less multiple scattering, ensure precision
measurements of 52.8MeV/c positrons. They also help to reduce annihilation
gamma-ray background for the gamma-ray detector. The commissioning
run of the MEG positron spectrometer will be performed in the end of 2006.
This innovative positron spectrometer and the commissioning run are
described here.
Author
Hajime Nishiguchi
(Uni Tokyo)
