First direct determination of the superallowed $\beta $-decay Q$_{EC}$-value for $^{14}$O

Superallowed 0$^{+}\to $0$^{+}$ nuclear $\beta $ transitions provide a sensitive test of the conserved vector current (CVC) hypothesis. While the CVC hypothesis calls for a constant corrected \textit{Ft}-value for all superallowed 0$^{+}\to $0$^{+} \beta $-decays, if there is a scalar interaction, an additional term approximately inversely proportional to Q$_{EC}$ would be present in \textit{Ft}. Hence the sensitivity to the presence of a scalar current would be larger for smaller Q$_{EC}$; i.e. for low-Z nuclei. Of the 14 \textit{Ft}-values that are used to calculate the world average, only the Q$_{EC}$ for $^{14}$O has not been measured in a Penning trap, despite multiple attempts at other facilities. We have performed the first direct measurement of the ground state $\beta $-decay Q$_{EC}$-value at the LEBIT facility. An order of magnitude improvement in precision makes it the most precisely known Q$_{EC}$-value for determining \textit{Ft} used in testing the CVC hypothesis.