Search

A first level scheme of ${}^{68}\mathrm{Se}$ with five states up to 4.2 MeV excitation energy and tentative spins ${6}^{+}$ and ${7}^{\ensuremath{-}}$ has been established from \ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\gamma} coincidences measured with six EUROBALL Cluster detectors in close geometry. The level scheme is interpreted in comparison with neutron deficient nuclei of the $A\ensuremath{\approx}70$ region and cranking model calculations. In a similar experiment a triple coincidence between the ${}^{72}\mathrm{Kr}$ transitions 710, 611, and 792 keV has been proven.

High spin states in the neutron deficient isotopes Ru90 and Ru91 have been studied in the 2p2n and 2pn exit channels of the reaction Ar-36 + Ni-58 using the 149 MeV Ar-36 beam at VICKSI and the OSIRIS array. By gating the gammagamma coincidences with evaporated neutrons and protons, excited states in Ru90 were identified for the first time and the level scheme of Ru-91 was extended. In both nuclei, the level energies and branching ratios follow the predictions of shell model calculations performed within the (1g9/2,2p1/2) single-particle space.

Mean lifetimes of high-spin states of Kr-74 have been determined using the Doppler-shift attenuation method. The high-spin states were studied using the Ca-40(Ca-40, alpha 2p) reaction at a beam energy of 160 MeV with the GASP gamma-ray spectrometer. The ground-state band and negative parity side band show the presence of three different configurations in terms of transitional quadrupole deformations. A dramatic shape change was found along the ground-state band after the S-band crossing. The deduced quadrupole deformation changes are well reproduced by cranked Woods-Saxon Strutinsky calculations.

The electromagnetic dipole response of ${}^{138}\mathrm{Ba}$ was measured up to 6.7 MeV excitation energy in a photon scattering experiment. Two Euroball Cluster detectors were used to detect the scattered photons under 94 and 132 degrees. The Cluster at 94 degrees served as a Compton polarimeter. The total observed dipole cross section is in good agreement with previous tagged photon data, but in the present experiment the transition strength and the electric character of most of the transitions has been determined on a state-by-state basis. The data show a concentration of $E1$ strength around 6 MeV. For one of the strongest excitations $M1$ character is suggested. The results of model calculations using the quasiparticle phonon model (QPM) agree with the observed electric dipole strength distribution.