The ${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$($2^{\mathrm{-}}$,g.s.)→${}^{16}$O(0 ${}_{}{}^{+}{}_{}{}^{}$,g.s.)${+\mathrm{e}}^{\mathrm{-}}$+ν${¯}_{\mathrm{e}}$ branching ratio is remeasured. A flatfield magnetic spectrometer, instrumented with a multiwire position-sensitive proportional detector, is used. A value for the branching ratio ${\Gamma }_{\beta }$${(2\mathrm{}}^{\mathrm{-}}$→$0^{+}$)/${\Gamma }_{\beta }$${(2\mathrm{}}^{\mathrm{-}}$ )=0.2811±0.0064 is determined. Combining this result with another recent determination produces a best value for this branching ratio. This in turn allows a more precise determination of the beta-decay rate (${\Lambda }_{\beta }$) for the process ${}_{}{}^{16}{}_{}{}^{}N$($0^{\mathrm{-}}$, 120 keV)→${}^{16}$O($0^{+}$,g.s.)${+\mathrm{e}}^{\mathrm{-}}$ +ν${¯}_{\mathrm{e}}$. A value ${\Lambda }_{\beta }$${(0\mathrm{}}^{\mathrm{-}}$→$0^{+}$)=0.489±0. 020 ${\sec }^{\mathrm{-}1}$ is obtained, which agrees with calculation only when pion exchange currents are included in the nucleon axial current.

• Received 11 March 1985

DOI:https://doi.org/10.1103/PhysRevC.31.2190