Resonant States ofMg24Excited by Protons on Sodium

Abstract

The gamma-ray yield from sodium was measured as a function of proton bombarding energy over the range 1.0 to 2.5 Mev using resolutions of 2.5 kev or better. In addition, the yield of $\alpha$ particles produced by the ${\mathrm{Na}}^{23}(p, \alpha ){\mathrm{Ne}}^{20}$ reaction and leading to the ground state of the residual nucleus was measured for proton energies of 1.0 to 2.2 Mev, with a resolution of 10 kev. Fifty-two resonances were observed in all. The resulting average level spacing is 28 kev at a mean excitation energy of 13.5 Mev in the compound nucleus ${\mathrm{Mg}}^{24}$. The resonances vary in natural width from less than 0.3 kev to 50 kev. The energy spectra of the gamma rays from a number of resonances were investigated with a single-crystal NaI(Tl) scintillation spectrometer. The spectra consist mainly of two gamma rays, with energies of 0.45±0.01 and 1.63±0.02 Mev. These are interpreted as transitions from the first excited states of the residual nuclei formed by the reactions ${\mathrm{Na}}^{23}(p, p^{\prime }){\mathrm{Na}}^{23}$ and ${\mathrm{Na}}^{23}(p, {\alpha }^{\prime }){\mathrm{Ne}}^{20}$, respectively.