Search For The Pygmy Dipole Resonance In Ni-68 At 600 Mev/Nucleon

The gamma decay from Coulomb excitation of Ni-68 at 600 MeV/nucleon on a Au target was measured using the RISING setup at the fragment separator of GSI. The Ni-68 beam was produced by a fragmentation reaction of Kr-86 at 900 MeV/nucleon on a Be-9 target and selected by the fragment separator. The gamma rays produced at the Au target were measured with HPGe detectors at forward angles and with BaF2 scintillators at backward angles. The measured spectra show a peak centered at approximately 11 MeV, whose intensity can be explained in terms of an enhanced strength of the dipole response function (pygmy resonance). Such pygmy structure has been predicted in this unstable neutron-rich nucleus by theory.