Measurement of nuclear moments in the region of light neutron-rich nuclei

I point out serious flaws in a recent calculation of energies and widths for levels of ¹⁷Na.

Lifetime measurements were performed on low-lying excited states of the neutron-rich isotope ${}^{17}\text{C}$ using the recoil shadow method. The γ-decay mean lifetimes were determined to be $583\pm 21(\text{stat})\pm 35(\text{syst})$ ps for the first excited state at 212 keV and $18.9\pm 0.6(\text{stat})\pm 4.7(\text{syst})$ ps for the second excited state at 333 keV. Based on a comparison with the empirical upper limits for the electromagnetic transition strengths, these decays are concluded to be predominantly M1 transitions. The reduced M1 transition probabilities to the ground state were deduced to be $(1.0\pm 0.1)\times {10}^{\mathrm{-2}}{\mu }_{\mathrm{N}}^2$ and $({8.2}_{\mathrm{-1.8}}^{\mathrm{+3.2}})\times {10}^{\mathrm{-2}}{\mu }_{\mathrm{N}}^2$, respectively, for the first and second excited states. The strongly hindered M1 strength as well as the lowered excitation energy represents unique nature of the 212-keV state.