18 research outputs found
Self-Consistent Nuclear Shell-Model Calculation Starting from a Realistic NN Potential
First self-consistent realistic shell-model calculation for the light p-shell
nuclei is performed, starting from the high-precision nucleon-nucleon (NN)
CD-Bonn potential. This realistic potential is renormalized deriving a
low-momentum NN potential V-low-k that preserves exactly the two-nucleon
low-energy physics. This V-low-k is suitable to derive a self-consistent
Hartree-Fock basis that is employed to derive both effective single-particle
energies and residual two-body matrix elements for the shell-model hamiltonian.
Results obtained show the reliability of such a fundamental microscopic
approach.Comment: 4 pages, 1 figure, 8 tables, to be published on Physics Letters
Simple approximation for the starting-energy-independent two-body effective interaction with applications to 6Li
We apply the Lee-Suzuki iteration method to calculate the linked-folded
diagram series for a new Nijmegen local NN potential. We obtain an exact
starting-energy-independent effective two-body interaction for a multi-shell,
no-core, harmonic-oscillator model space. It is found that the resulting
effective-interaction matrix elements can be well approximated by the Brueckner
G-matrix elements evaluated at starting energies selected in a simple way.
These starting energies are closely related to the energies of the initial
two-particle states in the ladder diagrams. The ``exact'' and approximate
effective interactions are used to calculate the energy spectrum of 6Li in
order to test the utility of the approximate form.Comment: 15 text pages and 2 PostScript figures (available upon request).
University of Arizona preprint, Number unassigne
Suppression of core polarization in halo nuclei
We present a microscopic study of halo nuclei, starting from the Paris and
Bonn potentials and employing a two-frequency shell model approach. It is found
that the core-polarization effect is dramatically suppressed in such nuclei.
Consequently the effective interaction for halo nucleons is almost entirely
given by the bare G-matrix alone, which presently can be evaluated with a high
degree of accuracy. The experimental pairing energies between the two halo
neutrons in He and Li nuclei are satisfactorily reproduced by our
calculation. It is suggested that the fundamental nucleon-nucleon interaction
can be probed in a clearer and more direct way in halo nuclei than in ordinary
nuclei.Comment: 11 pages, RevTex, 2 postscript figures; major revisions, matches
version to appear in Phys. Rev. Letter
Nuclear Shell Model Calculations with Fundamental Nucleon-Nucleon Interactions
Some fundamental Nucleon-Nucleon interactions and their applications to
finite nuclei are reviewed. Results for the few-body systems and from
Shell-Model calculations are discussed and compared to point out the advantages
and disadvantages of the different Nucleon-Nucleon interactions. The recently
developed Drexel University Shell Model (DUSM) code is mentioned.Comment: 16 pages, 4 figures. To appear in Phys. Rep. 199
SMMC method for two-neutrino double beta decay
Shell Model Monte Carlo (SMMC) techniques are used to calculate two-neutrino
double beta decay matrix elements. We validate the approach against direct
diagonalization for Ca in the complete -shell using the KB3
interaction. The method is then applied to the decay of Ge in the
model space using a newly calculated realistic
interaction. Our result for the matrix element is MeV, in
agreement with the experimental value.Comment: 10 pages, 3 figures available at
http://www.krl.caltech.edu/preprints/MAP.htm
Bonn Potential and Shell-Model Calculations for 206,205,204Pb
The structure of the nuclei 206,205,204Pb is studied interms of shell model
employing a realistic effective interaction derived from the Bonn A
nucleon-nucleon potential. The energy spectra, binding energies and
electromagnetic properties are calculated and compared with experiment. A very
good overall agreement is obtained. This evidences the reliability of our
realistic effective interaction and encourages use of modern realistic
potentials in shell-model calculations for heavy-mass nuclei.Comment: 4 pages, 4 figures, submitted to Physical Review
Realistic shell-model calculations for proton particle-neutron hole nuclei around 132Sn
We have performed shell-model calculations for nuclei with proton particles
and neutron holes around 132Sn using a realistic effective interaction derived
from the CD-Bonn nucleon-nucleon potential. For the proton-neutron channel this
is explicitly done in the particle-hole formalism. The calculated results are
compared with the available experimental data, particular attention being
focused on the proton particle-neutron hole multiplets. A very good agreement
is obtained for all the four nuclei considered, 132Sb, 130Sb, 133Te and 131Sb.
We predict many low-energy states which have no experimental counterpart. This
may stimulate, and be helpful to, future experiments.Comment: 8 pages, 6 figures, to be published on Physical Review
Microscopic description of nuclei in the middle of the pf-shell by a shell model calculation with G-matrix interaction
Energy levels and electromagnetic properties of with nuclides
are studied in terms of a large-scale shell model calculation, which contains
no newly adjusted parameters. The Kuo-Brown -matrix interaction is shown to
reproduce energy levels of 205 low-lying states of these nuclei. We evaluate
effective charges by incorporating the core-polarization effects caused by the
coupling to GQR's. We then compute E2 moments and transition probabilities. The
M1 moments and transition rates are calculated by quoting the effective
-factors of Towner, which are obtained by taking into account the
meson-exchange and the core-polarization mechanisms. By this microscopic
calculation most of the E2 properties and the magnetic moments are reproduced.
Although there are agreements and disagreements in the M1 transition rates, the
general tendency is reproduced. The and excitation from the
ground state to some low-lying states is also discussed.Comment: 63 pages (LaTeX, to be published in Nucl. Phys. A
Shell-model calculations and realistic effective interactions
A review is presented of the development and current status of nuclear
shell-model calculations in which the two-body effective interaction is derived
from the free nucleon-nucleon potential. The significant progress made in this
field within the last decade is emphasized, in particular as regards the
so-called V-low-k approach to the renormalization of the bare nucleon-nucleon
interaction. In the last part of the review we first give a survey of realistic
shell-model calculations from early to present days. Then, we report recent
results for neutron-rich nuclei near doubly magic 132Sn and for the whole
even-mass N=82 isotonic chain. These illustrate how shell-model effective
interactions derived from modern nucleon-nucleon potentials are able to provide
an accurate description of nuclear structure properties.Comment: 71 pages, to be published in Progress in Particle and Nuclear Physic
Effective shell-model hamiltonians from realistic nucleon-nucleon potentials within a perturbative approach
This paper discusses the derivation of an effective shell-model hamiltonian
starting from a realistic nucleon-nucleon potential by way of perturbation
theory. More precisely, we present the state of the art of this approach when
the starting point is the perturbative expansion of the Q-box vertex function.
Questions arising from diagrammatics, intermediate-states and order-by-order
convergences, and their dependence on the chosen nucleon-nucleon potential, are
discussed in detail, and the results of numerical applications for the p-shell
model space starting from chiral next-to-next-to-next-to-leading order
potentials are shown. Moreover, an alternative graphical method to derive the
effective hamiltonian, based on the Z-box vertex function recently introduced
by Suzuki et al., is applied to the case of a non-degenerate (0+2) hbaromega
model space. Finally, our shell-model results are compared with the exact ones
obtained from no-core shell-model calculations.Comment: 40 pages, 22 figures, 4 tables. Accepted for publication in Annals of
Physic