FRAGMENTATION OF LOW-LYING DIPOLE STRENGTH IN THE ODD-MASS NUCLEUS CS-133

The fragmentation of low-lying dipole strength in the odd-mass nucleus Cs-133 has been investigated in nuclear resonance fluorescence (NRF) experiments performed at the bremsstrahlung beam of the Stuttgart Dyna mitron accelerator at an end-point energy of 4.1 MeV. In the excitatio n energy range 2.3 - 3.7 MeV in total 22 new dipole excitations were o bserved. From the high-resolution gamma-ray spectra measured by three high-efficiency Ge detectors the reduced excitation probabilities B(E1 )up arrow or B(M1)up arrow were deduced. The fragmentation and absolut e total strengths of the detected dipole excitations are compared with results for the neighboring even-even, gamma-soft nucleus Ba-134, whe re both, rather strong scissors mode-like M1 and two-phonon E1 excitat ions are known from recent NRF experiments.