Role of the Mechanism of Heavy Cluster Stripping in a 27Al(р, α)24Mg Reaction

Resumo

The contribution from the mechanism of heavy ²³Na cluster stripping from a ²⁷Al(5/2⁺) initial nucleus to a cross section of the ²⁷Al(р, α)²⁴Mg(0⁺, 2⁺) reaction is calculated at E_p = 7.4 MeV and angles of α‑particle emission of 25°–160° (laboratory). Calculations are made with the FRESCO code using the contribution from the 3/2⁺ ground state of ²³Na. Spectroscopic amplitudes at decay vertices of ²⁷Al(5/2⁺) → ²³Na(3/2⁺) + α and ²⁴Mg(0⁺, 2⁺) → ²³Na(3/2⁺) + р reactions are determined from wave functions in the context of the Nilsson model, depending on their deformation. Cross sections calculated for the 0⁺ and 2⁺ levels of the ²⁴Mg nucleus are two orders of magnitude lower than those found experimentally. The cross section for the 0⁺ level grows at θ_α ∼ 180° in the back semi-sphere, while the one for the 2⁺ level exhibits a maximum at θ_α > 140°. The slight contribution from the mechanism of heavy cluster stripping is due to the spectroscopic amplitudes at the decay vertices of the initial and final nuclei owing to a weak overlap of wave functions of ²⁷Al, ²³Na, and ²⁴Mg(0⁺, 2⁺) nuclei in the Nilsson model.