Precise branching ratio measurements in ${}^{19}$Ne beta decay and fundamental tests of the weak interaction

Abstract

We used the 8$\ddot{I}€$ ${\hat{I}}^3$-ray spectrometer at the TRIUMF-ISAC radiocative ion beam facility to obtain high-precision branching ratios for ${}^{19}$Ne $β^+$ decay to excited states in ${}^{19}$F. Together with other previous work, our measurements determine the superallowed $1/2^{+}\to 1/2^{+}$ beta branch to the ground state in ${}^{19}$F to be 99.9878(7)\%, which is three times more precise than known previously. The implications of these measurements for testing a variety of weak interaction symmetries are discussed briefly.