The decay pattern of the Pygmy Dipole Resonance of 140Ce

The decay properties of the Pygmy Dipole Resonance (PDR) have been investigated in the semi-magic N=82 nucleus Ce-140 using a novel combination of nuclear resonance fluorescence and gamma-gamma coincidence techniques. Branching ratios for transitions to low-lying excited states are determined in a direct and model-independent way both for individual excited states and for excitation energy intervals. Comparison of the experimental results to microscopic calculations in the quasi-particle phonon model exhibits an excellent agreement, supporting the observation that the Pygmy Dipole Resonance couples to the ground state as well as to low-lying excited states. A 10% mixing of the PDR and the [2(1)(+) x PDR] is extracted. (C) 2016 The Authors. Published by Elsevier B.V.