ELECTRIC AND MAGNETIC DIPOLE EXCITATIONS TO BOUND-STATES IN GE-70,GE-72,GE-74,GE-76

The nuclei Ge-70,Ge-72,Ge-74,Ge-76 were studied by nuclear resonance fluorescence (NRF) experiments. Partially linearly polarized and unpolarized bremsstrahlung of 9 to 14 MeV endpoint energy was used at the Giessen 65 MeV electron linear accelerator; unpolarized bremsstrahlung of 4 MeV endpoint energy was used at the Stuttgart Dynamitron. The scattered photons were detected by Ge gamma-ray spectrometers with high energy resolution. Multipolarities were determined by measuring the angular correlations between the beam and the scattered gamma rays at different scattering angles. Precise excitation energies and ground-state decay widths of numerous (> 120) previously unknown spin-1 states were extracted. For 65 ground-state transitions (20 M1 transitions, 45 E1 transitions) parities were assigned, in a model-independent way, by polarized bremsstrahlung. A detailed distribution of electric and magnetic dipole strength in the even Ge isotopes was established.