Angular Distributions of Neutrons fromAl27(d, n)Si28

Abstract

By using the method of proton recoils in nuclear emulsions, angular distributions of neutrons emitted to low-lying states of ${\mathrm{Si}}^{28}$ in the reaction ${\mathrm{Al}}^{27}(d, n){\mathrm{Si}}^{28}$ have been obtained at deuteron energies of 2.16 and 6.00 Mev. As might be expected, the angular distributions obtained at $E_d=2.16\mathrm{}$ Mev show considerable deviations from the predictions of the simple Butler stripping theory. The angular distributions obtained at $E_d=6.00\mathrm{}$ Mev have been analyzed by means of the Butler theory to obtain parities and limits on the spins of ${\mathrm{Si}}^{28}$ states. These results are, for the ground state, $J^{\pi }=0^{+}, 1^{+}, 4^{+}, or 5^{+}$; 1.78-Mev state, $J^{\pi }=2^{+} or 3^{+}$; 4.62-Mev state, $J^{\pi }=1^{-} \mathrm{to} 4^{-}$; 6.24-Mev state, $J^{\pi }=2^{+} or 3^{+}$; 6.88-Mev state, $J^{\pi }=\left(1^{-} \mathrm{to} 4^{-}\right)$; 7.90-Mev state, $J^{\pi }=2^{+} or 3^{+}$; 8.57-Mev state, $J^{\pi }=2^{+} or 3^{+}$; 9.39-Mev state, $J^{\pi }=2^{+} or 3^{+}$. It is pointed out that the odd parity of the 4.62-Mev state of ${\mathrm{Si}}^{28}$ is consistent with the possible shell-model states of a spheroidal nucleus.