Measurement of the Branching Ratio for the Beta Decay of ${}^{14}$O

Abstract

We present a new measurement of the branching ratio for the decay of ${}^{14}$O to the ground state of ${}^{14}$N. The experimental result, ${\lambda }_0/{\lambda }_{\mathrm{total}}=(4.934\pm 0.040(stat.)\pm 0.061(syst.))\times 10^{-3}$, is significantly smaller than previous determinations of this quantity. The new measurement allows an improved determination of the partial halflife for the superallowed $0^{+}\to 0^{+}$ Fermi decay to the ${}^{14}$N first excited state, which impacts the determination of the $V_{ud}$ element of the CKM matrix. With the new measurement in place, the corrected ${}^{14}$O $\mathcal{F}t$ value is in good agreement with the average $\mathcal{F}t$ for other superallowed $0^{+}\to 0^{+}$ Fermi decays.

8 pages, 4 figures