We report the first direct measurement of the 14O superallowed Fermi β-decay QEC-value, the last of the so-called "traditional nine" superallowed Fermi β-decays to be measured with Penning trap mass spectrometry. 14O, along with the other low-Z superallowed β-emitter, 10C, is crucial for setting limits on the existence of possible scalar currents. The new ground state QEC value, 5144.364(25) keV, when combined with the energy of the 0+ daughter state, Ex(0+)=2312.798(11)~keV [Nucl. Phys. A {\bf{523}}, 1 (1991)], provides a new determination of the superallowed β-decay QEC value, QEC(sa)=2831.566(28) keV, with an order of magnitude improvement in precision, and a similar improvement to the calculated statistical rate function f. This is used to calculate an improved Ft-value of 3073.8(2.8) s.
@article{arxiv.1503.08124,
title = {First direct determination of the superallowed $\beta$-decay $Q_{EC}$-value for $^{14}$O},
author = {A. A. Valverde and G. Bollen and M. Brodeur and R. A. Bryce and K. Cooper and M. Eibach and K. Gulyuz and C. Izzo and D. J. Morrissey and M. Redshaw and R. Ringle and R. Sandler and S. Schwarz and C. S. Sumithrarachchi and A. C. C. Villari},
journal= {arXiv preprint arXiv:1503.08124},
year = {2015}
}