Calculations for diabolic pair-transfer below the Coulomb barrier

Abstract

Calculations of the probabilities for two-neutron transfer in the reaction²⁰⁸Pb +¹⁶²Dy at bombarding energies below the Coulomb barrier are presented. The reaction is dominated by the strong Coulomb excitation of the rotational bands in¹⁶²Dy and¹⁶⁴Dy, while the transfer process is a weak perturbation. The presence of a diabolic point in the interval [10⁺–12⁺] in the rotational sequence, above which the transfer matrix elements change sign, leads to a reduction in the total probability for transfer of up to 25%. The relative populations of the spin states above the diabolic point exhibit an even more pronounced variation.