Spin and Parity of the First Excited State ofNa23

Abstract

The angular distributions of the 440-kev gamma radiation resulting from the ${\mathrm{Na}}^{23}(p, p^{\prime }\gamma ){\mathrm{Na}}^{23}$ reaction have been measured for proton bombarding energies of 1.288 and 1.460 Mev. Decay by inelastically scattered protons is particularly favorable for these two well-isolated resonances in ${\mathrm{Mg}}^{24}$. The results show a marked anisotropy, thereby ruling out the possibility that the first excited state of ${\mathrm{Na}}^{23}$ has spin $J=\frac{1}{2}$. Otherwise the experiments do not permit a completely unambiguous assignment. Evidence is presented, however, showing that the most plausible assignment is $J=\frac{5}{2}+$.