Apparatus for a search for T-violating muon polarization in stopped-kaon decays

Abstract

The detector built at KEK to search for T-violating transverse muon polarization in K +→ π 0 μ +ν μ ( K μ3 ) decay of stopped kaons is described. Sensitivity to the transverse polarization component is obtained from reconstruction of the decay plane by tracking the μ + through a toroidal spectrometer and detecting the π 0 in a segmented CsI(Tl) photon calorimeter. The muon polarization was obtained from the decay positron asymmetry of muons stopped in a polarimeter. The detector included features which minimized systematic errors while maintaining high acceptance.