Mg24(O16, C12)Si28 and Mg24(O16, O16)Mg24 reactions at backward angles

Excitation functions of the Mg24(O16, C12)Si28 and Mg24(O16, O16)Mg24 reactions to the ground states and first-excited 2+ states in Si28 and Mg24 have been measured at θc.m.=180°over the energy range 24≤Ec.m.≤40 MeV, where the Mg24(O16, C12)Si28 reaction is known to exhibit a strong resonant behavior at forward angles. The four measured excitation functions show prominent structures, about 1 MeV wide, strongly correlated in the elastic and inelastic channels. Angular distributions in the range 110°≤θc.m. ≤180°were measured at Ec.m.=27.8, 30,8, and 36.2 MeV. At 27.8 and 36.2 MeV, where prominent peaks exist in the (O16, C12) backward-angle excitation function, the angular distributions of the transfer to the 0+ ground state are strongly rising toward 180°and have an oscillatory shape. The partial waves L=(20,22) and 26, respectively, are predominant at these two energies. At 30.8 MeV the data indicate the interference between odd and even partial waves. NUCLEAR REACTIONS Mg24(O16, C12), Mg24(O16, O16) Ec.m.=24-40 MeV; measured σ(E,θ); correlation analysis; DWBA and PL2 analyses; deduced J values.