Parity assignments in Ce140 up to 7 MeV using Compton polarimetry

Parity quantum numbers of J=1 states up to 7 MeV in the region of the Pygmy Dipole Resonance in Ce-140 were determined model independently by combining the methods of Nuclear Resonance Fluorescence and Compton polarimetry. For the first time the well-established method of Compton polarimetry was applied at such high energies. The experiment was performed using a fourfold segmented HPGe clover detector for the detection of the scattered photons. For all investigated dipole transitions asymmetries are found which correspond to negative parity of the excited states.