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 140 Ce using a novel combination of nuclear resonance fluorescence and γ – γ 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 + × PDR ] is extracted. [ABSTRACT FROM AUTHOR]