Bulletin of the American Physical Society
2010 Fall Meeting of the APS Division of Nuclear Physics
Volume 55, Number 14
Tuesday–Saturday, November 2–6, 2010; Santa Fe, New Mexico
Session CC: Mini-symposium on Nuclear Structure Theory and Experiments for Rare Isotopes I |
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Chair: Walid Younes, Lawrence Livermore National Laboratory Room: Sweeny C |
Thursday, November 4, 2010 8:30AM - 9:06AM |
CC.00001: Structure Theory for FRIB Invited Speaker: The forthcoming Facility for Rare Isotope Beams (FRIB) will produce nuclei close the limits of stability. Understanding and predicting the existence of these nuclei require pushing the nuclear structure theory to new limits. In my talk I will review the present status of the nuclear structure theory and its direction for the forthcoming years. I will emphasize the role of the configuration interaction method and its outcomes, which includes low-lying state spectroscopy, electromagnetic transitions amplitudes, spectroscopic factors, charge-exchange amplitudes, nuclear level densities, spectroscopic factors, and (double) beta decays. [Preview Abstract] |
Thursday, November 4, 2010 9:06AM - 9:18AM |
CC.00002: Renormalized Interactions with EDF Single-Particle Basis States Angelo Signoracci, Alex Brown, Morten Hjorth-Jensen We calculate renormalized interactions starting from nucleon-nucleon interactions such as N3LO for the sd and pf model spaces. The new aspect of our method is to use single-particle energy spectra and single-particle radial wavefunctions derived from energy-density functionals, in place of the conventional harmonic-oscillator basis. We find that two-body matrix elements derived for these model spaces are sensitive to the basis and can change depending on the core nucleus. In particular, the two-body matrix elements are reduced if they involve weakly bound orbitals. This is important for nuclei near the neutron drip line. [Preview Abstract] |
Thursday, November 4, 2010 9:18AM - 9:30AM |
CC.00003: Configuration Interactions Constrained by Energy Density Functionals Alex Brown, Angelo Signoracci, Morten Hjorth-Jensen A new method for constructing a Hamiltonian for configuration interaction calculations with constraints to energies of spherical configurations obtained with energy-density-functional (EDF) methods is presented. This results in a unified model that reproduces the EDF binding-energy results in the limit of single-Slater determinants, but can also be used for obtaining energy spectra and correlation energies with renormalized nucleon-nucleon interactions. The three-body and/or density-dependent terms that are necessary for good nuclear saturation properties are contained in the EDF. Applications to binding energies and spectra in the region of $^{208}$Pb are given. [Preview Abstract] |
Thursday, November 4, 2010 9:30AM - 9:42AM |
CC.00004: Making Effective Interactions More Effective Calvin Johnson Modern effective interactions for nuclear structure calculations use phase-equivalent potentials, connected by specific choices of unitary transformations. I consider the most general transformation and constrain the generators with many-body data, aided by singular value decomposition. In a nontrivial application to a two-component fermion gas at the unitary limit; I get significant improvement with many-body data--up to a ten-fold reduction in the root-mean-square error on the ground state energies. I will also discuss the application to nuclear structure. [Preview Abstract] |
Thursday, November 4, 2010 9:42AM - 9:54AM |
CC.00005: Triples Counting and Three-Nucleon Forces in Light Nuclei Robert B. Wiringa, Steven C. Pieper, Ivan Brida We report Green's function Monte Carlo studies of three-nucleon forces (3NF) in light nuclei. The 3NF components studied include the two-pion $s$-wave and $p$-wave terms (both anticommutator and commutator pieces) and one-pion/short- and short-/short-range phenomenological terms. (In chiral effective field theories, these correspond to the $c_1$, $c_3$, $c_4$, $c_D$, and $c_E$ terms, respectively.) Their contributions to the energy of light ($A~\leq~10$) nuclei is broken down by total spin $S$ and isospin $T$ = 1/2 or 3/2 and both the uncorrelated and correlated distributions of these triples are counted. We also study the energy dependence on the short-range cutoffs of the 3NF component functions and examine various projections to isolate specific contributions of 3NF to halo nuclei. [Preview Abstract] |
Thursday, November 4, 2010 9:54AM - 10:06AM |
CC.00006: The Importance Truncated No-Core Shell Model applied to the 0p-shell Michael Kruse, Petr Navratil, Bruce Barrett The No-Core Shell Model (NCSM) is a powerful ab-initio tool, used to calculate observables in light nuclei ($A<16$), starting from realistic two- and three-body forces. However, most of these calculations become increasingly difficult to perform as the number of nucleons is inreased. Even when soft, unitary transformed interactions (SRG etc) are used, a basis space of several oscillators shells is required ($N_{max}=14-20$), to reach convergence for $A>7$. Currently, the size of the model space is computationally impossible. Importance truncation selects a-priori, which basis states should be kept in the calculation, and which should be discarded. This procedure reduces the basis dimension considerably, yet captures enough of the physics to accurately describe the low-lying states in detail. In the case of the 0p-shell, several interesting nuclei lie near the neutron-drip lines, for which we will show results. The possibility to study reactions in the IT-NCSM/RGM framework will also be presented. [Preview Abstract] |
Thursday, November 4, 2010 10:06AM - 10:18AM |
CC.00007: Relativistic effects in intermediate-energy reactions involving halo nuclei Pierre Capel, Filomena Nunes The advent of radioactive-ion beams in the mid 80s has led to the discovery of halo nuclei. Several reaction models have been developed to infer information about this exotic nuclear structure from measurements. These models rely on different assumptions: semiclassical [1] or eikonal [2] approximations, or a discretization of the continuum [3]. Though these models are usually in fair agreement with experiment, there remain some disagreements between their predictions. In order to better understand these difference, and in particular the role played by relativistic effects at these energies, we analyse various corrections found in the literature, and compare their effects within these different reaction models.\\[4pt] [1] H. Esbensen and G. F. Bertsch, Nucl. Phys. A 600, 37 (1996).\\[0pt] [2] D. Baye, P. Capel, and G. Goldstein, Phys. Rev. Lett. 95, 082502 (2005).\\[0pt] [3] J. A. Tostevin, F. M. Nunes, and I. J. Thompson, Phys. Rev. C 63, 024617 (2001). [Preview Abstract] |
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