Gamma Rays from the 1.83-Mev Resonance in the ReactionMg24(p, γ)Al25

Abstract

The ${\mathrm{Mg}}^{24}(p, \gamma ){\mathrm{Al}}^{25}$ reaction has been studied in the range of proton energies from 1.66 Mev to 2.02 Mev. A new resonance at 1.833±0.007 Mev was observed which corresponds to an excited state of 4.047±0.010 Mev in ${\mathrm{Al}}^{25}$. The new excited state was observed to decay by the emission of 4.01±0.04, 2.43±0.04, and 1.62±0.03 Mev gamma rays. The last two gamma rays were observed to be in coincidence and the intensity ratio of the first two gamma rays was found to be 60±10:40±10. The experimental value of $\omega \gamma =\frac{(J+\frac{1}{2}){\Gamma }_p{\Gamma }_{\gamma }}{\Gamma }$, for the ground state transition was found to be 3×${10}^{-3\mathrm{}}$ ev and an upper limit of 10 kev was estimated for $\Gamma$ the total width of the resonance. Angular distribution measurements have shown that the angular momentum of the new state is either $\frac{5}{2}$ or $\frac{9}{2}$ with the latter value favored. On the basis of the observed dipole-quadrupole admixtures found for the gamma rays the parity of the new state is probably even. A discussion is given of the place of the new state in the rotational-like bands of ${\mathrm{Al}}^{25}$.