Narrow Results

The scissors mode plays a crucial role in the study of the unitary Fermi gas. In this paper, we simulate the scissors mode by solving the hydrodynamic equations with appropriate initial conditions, and then extract the flow field of the gas. The flow fields in different regimes are found to be essentially different. The characteristic differences in the flow patterns between the superfluid and the normal viscous fluid are presented. Irrotational flow signals superfluidity, while rotational one indicates normal hydrodynamical behavior. These different characteristics can be visualized by the velocity portraits of the flow, which provide an intuitive way to discriminate the states of the Fermi gas.

The scissors mode structure is studied in the actinides within the Wigner Function Moments method. The theory predicts a splitting of the scissors mode into three branches due to spin degrees of freedom. The excitation energies and $B(M1)$ transition probabilities for the scissors states are calculated for even–even axial nuclei of the actinide mass region. The origin of the double-humped structure of the scissors spectrum observed in the lightest actinides is discussed. The energy centroids and integrated $M1$ strengths for the transuranium nuclides up to ${}^{256}$No are predicted. The results of calculations for ${}^{232}$Th, ${}^{238}$U and ${}^{254}$No are compared with available experimental data.

This contribution reports on progress in the measurement of the full dipole excitation strength in ⁷⁶Se.The experiments used the nuclear resonance fluorescence technique at two facilities, the photon scattering setup at the S-DALINAC at the TU Darmstadt, and the polarization setup at HIGS at TUNL. Data indicates sub-structure of the pygmy dipole resonance, and reveals a candidate for the scissors mode in ⁷⁶Se. The final aim of the study is the determination of dipole strength distributions in the double-beta decay partners ⁷⁶Se and ⁷⁶Ge.