Wide-gap spark-chamber study ofKL0→π+e+νdecay

Abstract

A wide-gap spark chamber operated in a magnetic field has been used to measure the energy dependence of the form factor ${f}_{+}({q}^{2}) \mathrm{in} {K}_{L}^{0}\ensuremath{\rightarrow}\ensuremath{\pi}+e+\ensuremath{\nu}$ decay. Decays of ${K}_{L}^{0}$ mesons in vacuum were detected in the -30\ifmmode^\circ\else\textdegree\fi{} neutral beam of the AGS at Brookhaven National Laboratory. ${K}_{e3}^{0}$ decays were identified by electromagnetic showers produced in a lead radiator plate between the two 12-inch gaps of the chamber. The linear parameter ${\ensuremath{\lambda}}_{+}$ in the form factor ${f}_{+}({q}^{2})$ was determined to be 0.040 \ifmmode\pm\else\textpm\fi{} 0.012, where the error includes uncertainties in the corrections for systematic effects. A study of these systematic effects and the resulting errors is presented.