Inverse kinematics Coulomb excitation of isovector quadrupole excitations of heavy nuclei for the investigation of the proton-neutron interaction in the valence space

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The proton-neutron degree of freedom and its role in the formation of collective quantum phenomena is one of the main interests of nuclear structure physics. Strong magnetic dipole (M1) transitions between nuclear excited states are a signature of their structural differences in terms of pn-symmetry. This project is dedicated to the identification of pn-non-symmetric quadrupole-collective states with quantum numbers Jpi = 2+. Their properties are sensitive to the pn-interaciton in the valence space. The levels of interest are populated by means of projectile-Coulomb excitation of heavy-ion beams delivered by the ATLAS accelerator at the Argnonne National Laboratory (ANL) on light-ion targets; their gamma decays are detected with the 4pi-gamma-spectrometer Gammasphere. Our approach to pn-non-symmetric 2+ states has proven very effective since it has been applied for the first time in an experiment in 2005. 14 subsequent experiments have been performed. Another seven experiments are planned to be performed within this project. We apply for funding for their execution and the data analysis. The results will contribute to an improved understanding of the deformation-dependence of vibrational excitations in heavy nuclei.