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The coupled-channel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations, defined by nuclear deformations. Proper treatment of such excitations is often essential to the accurate description of reaction experimental data. Previous works have applied different models to specific nuclei with the purpose of determining angular-integrated cross sections. In this work, we present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions in a consistent manner for neutron-induced reactions on nuclei in the rare-earth region. This specific subset of the nuclide chart was chosen precisely because of a clear static deformation pattern. We analyze the convergence of the coupled-channel calculations regarding the number of states being explicitly coupled. Inspired by the work done by Dietrich et al., a model for deforming the spherical Koning-Delaroche optical potential as function of quadrupole and hexadecupole deformations is also proposed. We demonstrate that the obtained results of calculations for total, elastic and inelastic cross sections, as well as elastic and inelastic angular distributions correspond to a remarkably good agreement with experimental data for scattering energies above around a few MeV. [ABSTRACT FROM AUTHOR]

A rigorous approach to study the temporal evolution of physical processes is to follow the development in time of a given initial state, by numerically solving the time-dependent Schrödinger equation. This represents a natural modeling of the dynamical behaviour. We considered the equation in two spatial coordinates, to describe deformed nuclear shapes. The Hamiltonian is discretized by special, functionally fitted difference formulae of the derivatives and then a Crank-Nicolson scheme is applied. The resulting linear system with large sparse matrix is solved by a variant of Conjugate Gradient Method. The numerical solution has been used to the description of the proton decay. We also discuss the treatment of numerical boundary conditions, the preparation of the initial wavefunction and the calculation of the decay rate through the flux. [ABSTRACT FROM AUTHOR]

The evolution of low-lying E1 strength is systematically analyzed in very neutron-rich Sn nuclei, beyond 132Sn until 166Sn, within the Relativistic Quasiparticle Random Phase Approximation. The great neutron excess favors the appearance of a deformed ground state for 142–162Sn. The evolution of the low-lying strength in deformed nuclei is determined by the interplay of two factors, isospin asymmetry and deformation: while greater neutron excess increases the total low-lying strength, deformation hinders and spreads it. Very neutron rich deformed nuclei may not be as good candidates as spherical nuclei like 132Sn for the experimental study of low-lying E1 strength. [ABSTRACT FROM AUTHOR]

We present elements of the construction of a reliable and robust computational package that could allow symmetry-unrestricted large-scale computations within the nuclear energy density functional theory. We summarize the salient features of the theoretical and computational framework and give a detailed description of our numerical codes. We illustrate how our technology can be applied to the spectroscopy of odd-mass nuclei in the rare-earth region. [ABSTRACT FROM AUTHOR]

Within quasiparticle random phase approximation (QRPA), Pyatov-Salamov method for the self-consistent determination of the isovector effective interaction strength parameter, restoring a broken isotopic symmetry for the nuclear part of the Hamiltonian, is used. The isospin admixtures in the ground state of the parent nucleus, and the isospin structure of the isobar analog resonance (IAR) state are investigated by including the pairing correlations between nucleons for 72–80Kr isotopes. Our results are compared with the spherical case and with other theoretical results. [ABSTRACT FROM AUTHOR]

The development of neutron skins as a function of the neutron number is investigated within a self-consistent framework based on deformed Hartree-Fock calculations with density dependent Skyrme forces and pairing correlations in BCS approximation. We study several isotopic chains and consider all the experimentally observed isotopes from neutron-deficient to neutron-rich. We discuss various possibilities to define the neutron skin thickness based on the differences between neutron and proton radii as well as definitions based on comparison of the tails of the neutron and proton density distributions. We finally discuss the effects of deformation on the neutron skin based on the example of Kr isotopes. We study the neutron skins in different directions for oblate and prolate shapes and discuss it in terms of the quadrupole components of the density distributions. [ABSTRACT FROM AUTHOR]

Fine structure in proton emission from the deformed states 141g.s.Ho (T1/2 = 4.1 ms) and 141mHo (T1/2 = 7.4 μs) has been discovered at Oak Ridge by detecting fusion evaporation residues with the Recoil Mass Spectrometer, Si-detectors and digital signal processing electronics. The branching ratios to the first 2+ excited state in 140Dy were measured to be Ipg.s.(2+) = 0.9±0.1% and Ipm(2+) = 1.7±0.5%. A comparison of the available calculations to the experimental values calls for further development of the theoretical models. [ABSTRACT FROM AUTHOR]

Proton decay half-lives can be calculated reliably using the idea of simple tunnelling probabilities within a WKB model. Just as simple, but much more intuitive is the approach of Gurvitz and Kalbermann of splitting the tunnelling potential into internal (bound state) and external (scattering state) parts. This is referred to as the Two-Potential approach to the tunnelling problem. For spherical nuclei there is not much to choose between TPA and WKB, but to extract reliable spectroscopic information from the dripline nuclei of interest, these methods must be extended to deformed potentials. We outline our approach for the case of spherical nuclei starting from a mean field HF potential using the Skyrme interaction and outline a programme of work leading to an extended 3-D TPA model. [ABSTRACT FROM AUTHOR]

Deformed relativistic Hartree (DRH) and relativistic Hartree-Bogoliubov (DRHB) models are developed aiming at a proper description of exotic nuclei, particularly the deformed ones with large spatial extension. In order to give an adequate description of both the contribution of the continuum and the large spatial distribution in some exotic nuclei, the DRH and DRHB equations are solved in a Woods-Saxon basis in which the radial wave functions have proper asymptotic behaviors at large distance from the nuclear center which is crucial for the formation of halo. The formalism and the numerical details of the DRH model and some preliminary results of the DRHB model are presented. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The low-lying 0+ states observed in large abundance in several deformed nuclei are investigated systematically within the microscopic quasiparticle-phonon model. Attention is paid at their quadrupole and pairing collective properties. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We derive the Canonical-basis Time-Dependent Hartree-Fock-Bogoliubov (CbTDHFB) equations using time-dependent variational principle with a special pairing energy functional. We obtain the isoscalar quadrupole strength functions for Neon isotopes with small-amplitude CbTDHFB calculation in the three-dimensional coordinate-space representation. [ABSTRACT FROM AUTHOR]

Recent studies of the backbending phenomenon in medium light weight nuclei near A∼ 60 expanded greatly our interest about how the single particle orbits are nonlinearly affected by the collective motion. As a consequence we have applied a modified version of the exponential model in mass region at A ∼ 60. A firm conclusion is obtained concerning the successful validity of the proposed modified model in describing the backbending phenomenon in this region. Comparison with different theoretical descriptions is discussed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]