102 research outputs found
Nuclear Physics with Great Fun
I have studied mainly five interesting subjects in about 50 years from 1961 to the present; these are [I] Gamow-Teller giant resonances with isobaric analog states (1961 - 1967), [II] cluster structure in nuclei (1965 - 1980), [III] hypernuclei (1980 - 1995), [IV] unstable nuclei (1987 - present), and [V] roles of pion (tensor force) in nuclei (2001 - present). The intension of these studies and their key points are summarized briefly
Relativisitic mean field theory of surface pion condensation in finite nuclei
We study the possible occurrence of surface pion condensation in finite
nuclei in the relativistic mean field (RMF) theory. We are led to this
conjecture due to the essential role of pions in few-body systems and the
recent (p,n) experiments performed at RCNP for spin-isospin excitations of
medium and heavy nuclei. We calculate explicitly various N=Z closed shell
nuclei with finite pion mean field in the RMF framework and demonstrate the
actual occurrence of surface pion condensation.Comment: 4 pages, 1 figur
Tensor correlation in 4He and its Effect on the doublet splitting in 5He
We investigate the role of tensor correlation on the structures of
\nuc{4}{He} and its effect on the doublet splitting in \nuc{5}{He}. We perform
a configuration mixing calculation in the shell model type bases to represent
the tensor correlation for He. It is found that our model describes the
characteristics of the tensor correlation, which is represented by an admixture
of the configuration with a spatially modified orbit. For
He, we solve a coupled OCM equation for an extended He+ model, while
taking into account the tensor correlation in the He cluster. It is shown
that the tensor correlation produces the Pauli blocking, in particular, for the
state, and its effect causes about half of the p-wave doublet
splitting in He. This indicates that the strength of the effective
spin-orbit interaction should be reduced by about half from the conventional
one. We obtain a reliable He- interaction, including the tensor
correlation, which further improves the behavior of the - and -wave phase
shifts in the He+ system.Comment: 21 pages, 9 figures, To be published in Progress of Theoretical
Physic
Resonances of 7He in the complex scaling method
We study the resonance spectroscopy of 7He in the 4He+n+n+n cluster model,
where the motion of valence neutrons is described in the cluster orbital shell
model. Many-body resonances are treated on the correct boundary condition as
the Gamow states in the complex scaling method. We obtain five resonances and
investigate their properties from the configurations. In particular, the 1/2-
state is found in a low excitation energy of 1.1 MeV with a width of 2.2 MeV,
while the experimental determination of the position of this state is not so
clear. We also evaluate the spectroscopic factors of the 6He-n components in
the obtained 7He resonances. The importance of the 6He(2+) state is shown in
several states of 7He.Comment: 7 pages, 4 figure
Coulomb breakup reactions of Li in the coupled-channel Li~+~~+~ three-body model
We investigate the three-body Coulomb breakup of a two-neutron halo nucleus
Li. We use the coupled-channel Li + + three-body model,
which includes the coupling between last neutron states and the various
- configurations in Li due to the tensor and pairing correlations.
The three-body scattering states of Li are described by using the
combined methods of the complex scaling and the Lippmann-Schwinger equation.
The calculated breakup cross section successfully reproduces the experiments.
The large mixing of the s-state in the halo ground state of Li is shown
to play an important role in explanation of shape and strength of the breakup
cross section. In addition, we predict the invariant mass spectra for binary
subsystems of Li. It is found that the two kinds of virtual s-states of
Li- and - systems in the final three-body states of Li
largely contribute to make low-lying peaks in the invariant mass spectra. On
the other hand, in the present analysis, it is suggested that the contributions
of the p-wave resonances of Li is hardly confirmed in the spectra.Comment: 26 pages, 11 figures, 2 tables, submitted to Phys. Rev.
Extended 9Li+n+n three-body model of 11Li with the pairing correlation in 9Li
We discuss the binding mechanism of 11Li based on an extended three-body
model of Li+n+n. In the model, we take into account the pairing correlation of
p-shell neutrons in 9Li, in addition to that of valence neutrons outside the
9Li nucleus, and solve the coupled-channel two- and three-body problems of 10Li
and 11Li, respectively. The results show that degrees of freedom of the pairing
correlation in 9Li play an important role in the structure of 10Li and 11Li. In
10Li, the pairing correlation in 9Li produces a so-called pairing-blocking
effect due to the presence of valence neutron, which degenerates s- and p-wave
neutron orbits energetically. In 11Li, on the other hand, the pairing-blocking
effect is surpassed by the core-n interaction due to two degrees of freedom of
two valence neutrons surrounding 9Li, and as a result, the ground state is
dominated by the p-shell closed configuration and does not show a spatial
extension with a large r.m.s. radius. These results indicate that the pairing
correlation is realized differently in odd- and even-neutron systems of 10Li
and 11Li. We further improve the tail part of the 9Li-n interaction, which
works well to reproduce the observed large r.m.s. radius in 11Li.Comment: 24 pages, 7 figures. to be published in Prog. Theor. Phy
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