First direct determination of the superallowed $\beta $-decay QEC-value for O-14 via Penning trap mass spectrometry at the LEBIT facility

Low-Z, superallowed $\beta $-emitters like O-14 are particularly significant for setting limits on the existence of scalar currents in the electroweak interaction. While the Conserved Vector Current (CVC) hypothesis states that Ft should be the same for all superallowed 0$+ \quad \to $ 0$+ \quad \beta $-decays, if there is a scalar interaction, an additional term approximately inversely proportional to QEC would be present in Ft. As QEC-values are smaller for lower-Z isotopes, these isotopes would be most sensitive to the presence of a scalar current, showing the largest deviation in Ft. To date, 14 Ft values are used to calculate the world average. Of these 14 decays, only O-14 had not been measured in a Penning trap, despite multiple attempts at other facilities. At LEBIT we have performed the first direct measurement of the ground state $\beta $-decay QEC value. This measurement provides an order of magnitude improvement in precision, and it no longer makes a significant contribution to the uncertainty of its associated Ft value.