The Coulomb excitation experiment to study electromagnetic properties of the heaviest stable Mo isotope, 100 Mo, was performed using a 76 MeV 32 S beam from the Warsaw cyclotron U-200P. Magnitudes and relative signs of 26 E1, E2, E3, and M1 matrix elements coupling nine low-lying states in 100 Mo were determined using the least-squares code GOSIA. Diagonal matrix elements (related to the spectroscopic quadrupole moments) of the 2 + 1 , 2 + 2 , and 2 + 3 states as well as the 4 + 1 state were extracted. The resulting set of reduced E2 matrix elements was complete and precise enough to obtain, using the quadrupole sum rules approach, quadrupole deformation parameters of 100 Mo in its two lowest 0 + states: ground and excited. The overall deformation of the 0 + 1 and 0 + 2 states in 100 Mo is of similar magnitude, in both cases larger compared to what was found for the neighboring isotopes 96 Mo and 98 Mo. At the same time, the asymetry parameters obtained for both states strongly differ, indicating a triaxial shape of the 100 Mo nucleus in the ground state and a prolate shape in the excited 0 + state. Low-energy quadrupole excitations of the 100 Mo nucleus were studied in the frame of the general quadrupole collective Bohr Hamiltonian model (GBH). The potential energy and inertial functions were calculated using the adiabatic time-dependent Hartree-Fock-Bogoliubov (ATDHFB) method starting from two possible variants of the Skyrme effective interaction: SIII and Sly4. The overall quadrupole deformation parameters resulting from the GBH calculations with the SLy4 variant of the Skyrme interaction are slightly closer to the experimentally obtained values than those obtained using SIII.

Article:Bree, N., Wrzosek-Lipska, K., Petts, A. et al. (67 more authors) (2014) Shape coexistence in the neutron-deficient even-even 182-188Hg isotopes studied via Coulomb excitation.

Lifetimes of states in the ground-state bands of (70)Se and (72)Se were measured using the recoil-distance Doppler shift method. The results deviate significantly from earlier measurements, requiring a revision of the conclusions drawn from a recent Coulomb excitation experiment concerning the shape of (70)Se. The new results lead to a coherent picture of shape coexistence in the neutron-deficient selenium and krypton isotopes. The coexistence and evolution of oblate and prolate shapes in this mass region is for the first time consistently described by new Hartree-Fock-Bogolyubov-based configuration-mixing calculations which were performed using the Gogny D1S interaction.

No abstract

No abstract

No abstract

No abstract

The results of the Doppler-shift attenuation method lifetime measurements in partner bands of 128Cs and 132La are presented. Experimental reduced transition probabilities in 128Cs are compared with theoretical calculations done in the frame of the core-quasiparticle coupling model. The electromagnetic properties, energy and spin of levels belonging to the partner bands show that 128Cs is the best known example revealing the chiral symmetry breaking phenomenon.