Mg26(t,He3)reaction and a spherical-shell-model description ofNa26

The ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}(t,{}_{}{}^3{}_{}{}^{}\mathrm{He})$ reaction at an incident energy of 23.5 MeV has been used to measure the ground-state mass and the energies of the excited states of ${}_{}{}^{26}{}_{}{}^{}\mathrm{Na}$. The measured mass excess (-6.903 ± 0.020 MeV) is in agreement with that measured using the ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$(${}_{}{}^7{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$) reaction and with the most recent $\beta$-decay end-point measurement. The spectrum of low-lying levels together with a recent assignment of $3^{+}$ for the ground-state spin are not consistent with a rotational interpretation for ${}_{}{}^{26}{}_{}{}^{}\mathrm{Na}$. These data, however, can be explained in terms of the spherical shell model.