790 research outputs found
Boson Transition Densities Within the Interacting-boson-model Picture - Rotational Limit
No full textRole of the gamma degree of freedom in sub-barrier fusion phenomena and effective barrier distributions
No full textWe investigate sub-barrier fusion phenomena in the presence of triaxial static deformations and under conditions of gamma instability. It is found that the distributions of effective barriers can reflect in a distinct way a general quadrupole profile specified in terms of both beta(2) and gamma. Fusion cross sections as a function of energy are, on the other hand, rather insensitive to the gamma degree of freedom
Excitation Patterns of Gamma-unstable Nuclei
No full textA detailed analysis of the Coulomb excitation of gamma-unstable bands in transitional nuclei is made. Approximate analytic expressions valid in the sudden limit are supplemented with coupled-channel calculations. The population patterns obtained with the quantal or semiclassical treatments are interpreted making use of the stationary phase approximation. A quantitative description of the excitation process is also developed in terms of a classical formalism which incorporates both relative motion and.the intrinsic gamma-degree of freedom. Applications are presented for the reaction Pb-208 + Pt-196
Surface Interaction Between Atomic Clusters
No full textThe effective interaction between metal clusters is calculated within the framework of the local-density Thomas-Fermi approximation. The resulting potentials can be parametrized in a general form valid for different sizes (via the curvatures of the two clusters) and different-systems (via the value of the surface tension). The characteristic features of the structure of the clusters are embodied in a ''universal'' function depending on the separation distance between their surfaces. Long-range contributions arising from the polarization of the two systems are also briefly discussed
Angular-momentum Stability of Small Atomic Clusters
No full textThe limits of stability of small atomic clusters with angular momentum are investigated as a function of the size and charge of the aggregates. Critical angular momenta are obtained in a di-cluster picture from the balance of a cohesive surface-surface interaction and the disruptive centrifugal and electric interactions. The calculation scheme incorporates the mass and charge asymmetry degrees of freedom and it is thus particularly suited to explore cluster-cluster reaction processes. Deformation of the fragments is taken into account
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