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Title: Beyond the Nuclear Shell Model

Abstract

Nuclei, the fuel that burns in stars, make up 99.9% of all baryonic matter in the universe. The complex nature of the nuclear forces among protons and neutrons generates a broad range and diversity of nuclear phenomena. Developing a comprehensive description of nuclei and their reactions represents one of the great intellectual opportunities for physics. As nuclear physicists have seen during the past 10 years, success will require theoretical and experimental investigations of isotopes with unusual neutron-to-proton ratios. Such nuclei, which are typically not found on Earth, are called exotic or rare.

Authors:
 [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
971566
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics Today; Journal Volume: 60; Journal Issue: 11
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; NEUTRONS; NUCLEAR FORCES; NUCLEI; PHYSICS; PROTONS; SHELL MODELS; STARS; UNIVERSE

Citation Formats

Dean, David Jarvis. Beyond the Nuclear Shell Model. United States: N. p., 2007. Web. doi:10.1063/1.2812123.
Dean, David Jarvis. Beyond the Nuclear Shell Model. United States. doi:10.1063/1.2812123.
Dean, David Jarvis. Mon . "Beyond the Nuclear Shell Model". United States. doi:10.1063/1.2812123.
@article{osti_971566,
title = {Beyond the Nuclear Shell Model},
author = {Dean, David Jarvis},
abstractNote = {Nuclei, the fuel that burns in stars, make up 99.9% of all baryonic matter in the universe. The complex nature of the nuclear forces among protons and neutrons generates a broad range and diversity of nuclear phenomena. Developing a comprehensive description of nuclei and their reactions represents one of the great intellectual opportunities for physics. As nuclear physicists have seen during the past 10 years, success will require theoretical and experimental investigations of isotopes with unusual neutron-to-proton ratios. Such nuclei, which are typically not found on Earth, are called exotic or rare.},
doi = {10.1063/1.2812123},
journal = {Physics Today},
number = 11,
volume = 60,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Experimental information on the energy distribution of states in the lowest lying configurations of selected odd-odd nuclei just beyond {sup 208}Pb is summarized. In {sup 210}Bi the {pi}0h{sub 9/2}{circle_times}{nu}1g{sub 9/2} configuration and other low lying configurations all have the inverted parabola shape in a plot of energy versus spin. When additional pairs of protons and/or neutrons are added, leading to heavier odd-odd nuclei, the inverted parabola becomes more compressed. Before these trends can be completed, however, quadrupole-octupole deformation sets in. Using the generalized intermediate coupling model, it is possible to reproduce these experimental trends and then to carry them tomore » completion in the reversed parabola (of energy versus spin) resulting from the configuration {pi}0h{sub 9/2}{circle_times}{nu}(1g{sub 9/2}){sup {minus}1} or {pi}(0h{sub 9/2}){sup {minus}1}{circle_times}{nu}1g{sub 9/2}. {copyright} {ital 1997} {ital The American Physical Society}« less
  • The No Core Shell Model (NCSM) is an ab initio method for calculating the properties of light nuclei, up to about A = 20, in which all A nucleons are treated as being active. It is difficult to go to larger A values due to the rapid grow of the basis spaces required in order to obtain converged results. In this presentation we briefly discuss three new techniques for extending the NCSM to heavier mass nuclei.
  • Van der Waals (vdW) coefficients can be accurately generated and understood by modelling the dynamic multipole polarizability of each interacting object. Accurate static polarizabilities are the key to accurate dynamic polarizabilities and vdW coefficients. In this work, we present and study in detail a hollow-sphere model for the dynamic multipole polarizability proposed recently by two of the present authors (JT and JPP) to simulate the vdW coefficients for inhomogeneous systems that allow for a cavity. The inputs to this model are the accurate static multipole polarizabilities and the electron density. A simplification of the full hollow-sphere model, the single-frequency approximationmore » (SFA), circumvents the need for a detailed electron density and for a double numerical integration over space. We find that the hollow-sphere model in SFA is not only accurate for nanoclusters and cage molecules (e.g., fullerenes) but also yields vdW coefficients among atoms, fullerenes, and small clusters in good agreement with expensive time-dependent density functional calculations. However, the classical shell model (CSM), which inputs the static dipole polarizabilities and estimates the static higher-order multipole polarizabilities therefrom, is accurate for the higher-order vdW coefficients only when the interacting objects are large. For the lowest-order vdW coefficient C{sub 6}, SFA and CSM are exactly the same. The higher-order (C{sub 8} and C{sub 10}) terms of the vdW expansion can be almost as important as the C{sub 6} term in molecular crystals. Application to a variety of clusters shows that there is strong non-additivity of the long-range vdW interactions between nanoclusters.« less