Michael D Chapman

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 μ 3 ) 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 π0 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.

Measurement of Γ(Kμ3)/Γ(Ke3) ratio using stopped positive kaons

Abstract The ratio of the K + → π 0 μ + ν ( K μ 3 + ) and K + → π 0 e + ν ( K e 3 + ) decay widths, Γ ( K μ 3 )/ Γ ( K e 3 ), has been measured with stopped positive kaons. K μ 3 + and K e 3 + samples containing 2.4×10 4 and 4.0×10 4 events, respectively, were analyzed. The Γ ( K μ 3 )/ Γ ( K e 3 ) ratio was obtained to be 0.671±0.007(stat.)±0.008(syst.) calculating the detector acceptance by a Monte Carlo simulation. The coefficient of the q 2 dependent term of the f 0 form factor was also determined to be λ 0 =0.019±0.005(stat.)±0.004(syst.) with the assumption of μ – e universality in K l 3 + decay. The agreement of our result with the λ 0 value obtained from K μ 3 + Dalitz plot analyses supports the validity of the μ – e universality.

High-precision magnetic field mapping with a three-dimensional Hall probe for a T-violation experiment in Kμ3 decay

Abstract High-precision magnetic-field mapping was performed for an experiment to search for a violation of time-reversal invariance in the K + → π 0 μ + ν μ decay at the KEK proton synchrotron. A commercially available three-dimensional Hall probe was used in conjunction with a specially designed mapping device and a goniometer system. Details concerning the measurement principle, calibration, actual measurements and analysis are described.

New experimental limits onKL0→μe andKL0→ee branching ratios

A search for the decays {ital K}{sub {ital L}}{sup 0}{r arrow}{mu}e and {ital K}{sub {ital L}}{sup 0}{r arrow}ee has produced no examples of either process. When normalized to the decay {ital K}{sub {ital L}}{sup 0}{r arrow}{pi}{sup +}{pi}{sup {minus}}, the 90%-C.L. upper limits on the branching ratios are {ital B}({ital K}{sub {ital L}}{sup 0}{r arrow}{mu}e){lt}2.2{times}10{sup {minus}10} and {ital B}({ital K}{sub {ital L}}{sup 0}{r arrow}ee){lt}3.2{times}10{sup {minus}10}.