472 research outputs found
Low-momentum nucleon-nucleon interaction and shell-model calculations
We discuss the use of the low-momentum nucleon-nucleon NN interaction V-low-k
in the derivation of the shell-model effective interaction and emphasize its
practical value as an alternative to the Brueckner G-matrix method. We present
some selected results of our current study of exotic nuclei around closed
shells, which have been obtained starting from the CD-Bonn potential. We also
show some results of calculations performed with different phase-shift
equivalent NN potentials, and discuss the effect of changes in the cutoff
momentum which defines the V-low-k potential.Comment: 5 pages, 5 figures, 1 table, Talk presented at CDN05, 31 Jan - 4 Feb
2005, University of Tokyo, Japa
Nuclear Structure Calculations and Modern Nucleon-Nucleon Potentials
We study ground-state properties of the doubly magic nuclei 4He, 16O, and
40Ca employing the Goldstone expansion and using as input four different
high-quality nucleon-nucleon (NN) potentials. The short-range repulsion of
these potentials is renormalized by constructing a smooth low-momentum
potential V-low-k. This is used directly in a Hartree-Fock approach and
corrections up to third order in the Goldstone expansion are evaluated.
Comparison of the results shows that they are only slightly dependent on the
choice of the NN potential.Comment: 5 pages, submitted to Physical Review
Proton-Neutron Interaction near Closed Shells
Odd-odd nuclei around double shell closures are a direct source of
information on the proton-neutron interaction between valence nucleons. We have
performed shell-model calculations for doubly odd nuclei close to Pb,
Sn and Sn using realistic effective interactions derived from
the CD-Bonn nucleon-nucleon potential. The calculated results are compared with
the available experimental data, attention being focused on particle-hole and
particle-particle multiplets. While a good agreement is obtained for all the
nuclei considered, a detailed analysis of the matrix elements of the effective
interaction shows that a stronger core-polarization contribution seems to be
needed in the particle-particle case.Comment: 8 pages, 6 figures, Proccedings of the International Conference
"Nuclear Structure and Related Topics", Dubna, Russia, September 2-6, 2003,
to be published in Yadernaia Fizika (Physics of Atomic Nuclei
Realistic shell-model calculations: current status and open problems
The main steps involved in realistic shell-model calculations employing
two-body low-momentum interactions are briefly reviewed. The practical value of
this approach is exemplified by the results of recent calculations and some
remaining open questions and directions for future research are discussed.Comment: 12 pages, 2 figures, contribution to J. Phys G, Special Issue, Focus
Section: Open Problems in Nuclear Structur
Realistic Shell-Model Calculations for Proton-Rich N=50 Isotones
The structure of the N=50 isotones 98Cd, 97Ag, and 96Pd is studied in terms
of shell model employing a realistic effective interaction derived from the
Bonn-A nucleon-nucleon potential. The single-hole energies are fixed by
resorting to an analysis of the low-energy spectra of the isotones with A>= 91.
Comparison shows that our results are in very satisfactory agreement with the
available experimental data. This supports confidence in the predictions of our
calculationsComment: 8 pages, 3 figures, to be published on Journal of Physics
Neutron-proton interaction in rare-earth nuclei: Role of tensor force
We investigate the role of the tensor force in the description of doubly odd
deformed nuclei within the framework of the particle-rotor model. We study the
rare-earth nuclei 174Lu, 180Ta, 182Ta, and 188Re using a finite-range
interaction, with and without tensor terms. Attention is focused on the lowest
K=0 and K=1 bands, where the effects of the residual neutron-proton interaction
are particularly evident. Comparison of the calculated results with
experimental data evidences the importance of the tensor-force effects.Comment: 8 pages, 5 figures, to be published on Physical Review
Low momentum nucleon-nucleon potential and shell model effective interactions
A low momentum nucleon-nucleon (NN) potential V-low-k is derived from meson
exhange potentials by integrating out the model dependent high momentum modes
of V_NN. The smooth and approximately unique V-low-k is used as input for shell
model calculations instead of the usual Brueckner G matrix. Such an approach
eliminates the nuclear mass dependence of the input interaction one finds in
the G matrix approach, allowing the same input interaction to be used in
different nuclear regions. Shell model calculations of 18O, 134Te and 135I
using the same input V-low-k have been performed. For cut-off momentum Lambda
in the vicinity of 2 fm-1, our calculated low-lying spectra for these nuclei
are in good agreement with experiments, and are weakly dependent on Lambda.Comment: 5 pages, 5 figure
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
Coexistence of 'alpha+ 208Pb' cluster structures and single-particle excitations in 212Po
Excited states in 212Po have been populated by alpha transfer using the
208Pb(18O,14C) reaction at 85MeV beam energy and studied with the EUROBALL IV
gamma multidetector array. The level scheme has been extended up to ~ 3.2 MeV
excitation energy from the triple gamma coincidence data. Spin and parity
values of most of the observed states have been assigned from the gamma angular
distributions and gamma -gamma angular correlations. Several gamma lines with
E(gamma) < 1 MeV have been found to be shifted by the Doppler effect, allowing
for the measurements of the associated lifetimes by the DSAM method. The
values, found in the range [0.1-0.6] ps, lead to very enhanced E1 transitions.
All the emitting states, which have non-natural parity values, are discussed in
terms of alpha-208Pb structure. They are in the same excitation-energy range as
the states issued from shell-model configurations.Comment: 21 pages, 19 figures, corrected typos, revised arguments in Sect.
III
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