The Mass of 22Mg

Mass measurements with a relative precision of better than 1.5×10^-8 were performed on ²²Mg and its reaction partners ²¹Na and ²²Na with the ISOLTRAP Penning trap mass spectrometer at CERN, yielding the mass excesses D(²²Mg)=-399.92(27) keV, D(²¹Na)=-2184.71(21) keV, and D(²²Na)=-5181.56(16) keV. The importance of these results is twofold. First, a comparative half-life (Ft value) has been obtained for the superallowed β decay of ²²Mg to further test the conserved-vector-current hypothesis. Second, the resonance energy for the ²¹Na proton capture reaction has been independently determined, allowing direct comparisons of observable γ radiation in nova explosions with the yield expected from models.