Excited-State Half-Lives in ^{130}Cd and the Isospin Dependence of Effective Charges.

The known I^{π}=8_{1}^{+}, E_{x}=2129-keV isomer in the semimagic nucleus ^{130}Cd_{82} was populated in the projectile fission of a ^{238}U beam at the Radioactive Isotope Beam Factory at RIKEN. The high counting statistics of the accumulated data allowed us to determine the excitation energy, E_{x}=2001.2(7)  keV, and half-life, T_{1/2}=57(3)  ns, of the I^{π}=6_{1}^{+} state based on γγ coincidence information.

Partial dynamical symmetry in quantum Hamiltonians with higher-order terms.

A generic procedure is proposed to construct many-body quantum Hamiltonians with partial dynamical symmetry. It is based on a tensor decomposition of the Hamiltonian and allows the construction of a hierarchy of interactions that have selected classes of solvable states. The method is illustrated in the SO(6) limit of the interacting boson model of atomic nuclei and applied to the nucleus 196Pt.

Correlating radii and electric monopole transitions of atomic nuclei.

A systematic analysis of the spherical-to-deformed shape phase transition in even-even rare-earth nuclei from 58Ce to 74W is carried out in the framework of the interacting boson model. These results are then used to calculate nuclear radii and electric monopole (E0) transitions with the same effective operator. The influence of the hexadecapole degree of freedom (g boson) on the correlation between radii and E0 transitions thus established is discussed.

Partial conservation of seniority and nuclear isomerism.

We point out the possibility of the partial conservation of the seniority quantum number when most eigenstates are mixed in seniority but some remain pure. This situation occurs in nuclei for the g(9/2) and h(9/2) shells where it is at the origin of the existence of seniority isomers in the ruthenium and palladium isotopes. It also occurs for f bosons.

Exact solution of the isovector neutron-proton pairing Hamiltonian.

The complete exact solution of the T = 1 neutron-proton pairing Hamiltonian is presented in the context of the SO(5) Richardson-Gaudin model with nondegenerate single-particle levels and including isospin symmetry-breaking terms. The power of the method is illustrated with a numerical calculation for for 64Ge for a pf + g9/2 model space which is out of reach of modern shell-model codes.

Deuteron transfer in N=Z nuclei.

Predictions are obtained for T=0 and T=1 deuteron-transfer intensities between self-conjugate N=Z nuclei on the basis of a simplified interacting boson model which considers bosons without orbital angular momentum but with full spin-isospin structure. These transfer predictions can be correlated with nuclear binding energies in specific regions of the mass table.

Rotating ground states of trapped atoms in a Bose-Einstein condensate with arbitrary two-body interactions.

In a k-dimensional system of weakly interacting Bose atoms trapped by a spherically symmetric and harmonic external potential, an exact expression is obtained for the rotating ground states at a fixed angular momentum. The result is valid for arbitrary interactions obeying minimal physical requirements. Depending on the sign of a modified scattering length, it reduces to either a collective rotation or a condensed vortex state, with no alternative.

Exact level densities for the harmonic oscillator.

The number of levels of a many-fermion system confined by a harmonic-oscillator potential is computed as a function of excitation energy. Because of its exact nature, the formalism accounts for effects of shell structure on the level density. The method is easily extended to a variety of situations as is illustrated with the inclusion of isospin and deformation effects as well as a calculation of the number of spurious states.