2,057 research outputs found
Continuum QRPA in the coordinate space representation
We formulate a quasi-particle random phase approximation (QRPA) in the
coordinate space representation. This model is a natural extension of the RPA
model of Shlomo and Bertsch to open-shell nuclei in order to take into account
pairing correlations together with the coupling to the continuum. We apply it
to the Sn nucleus and show that low-lying excitation modes are
significantly influenced by the pairing effects although the effects are
marginal in the giant resonance region. The dependence of the pairing effect on
the parity of low-lying collective mode is also discussed.Comment: RevTex, 21 pages, 10 eps figure
Odd-even staggering of reaction cross sections for 22,23,24O isotopes
The interaction cross sections of O nuclei at 900 MeV/nucleon have
been measured recently by Kanungo {\it et al.}. We show that the odd-even
staggering parameter of interaction cross sections deduced from these new data
agrees well with the theoretical systematics expected for the neutron
separation energy of =2.740.120 MeV for O. We also discuss
briefly the energy dependence of the staggering parameter.Comment: 2 pages, 1 figur
Interplay between isoscalar and isovector correlations in neutron-rich nuclei
The interplay between isoscalar and isovector correlations in the 1
states in neutron-rich (NZ) even-even nuclei is studied, taking examples
of the nuclei, O and O. The excitation
modes explored are isovector dipole and isoscalar compression dipole modes. The
self-consistent Hartree-Fock plus the random-phase approximation with the
Skyrme interaction, SLy4, is solved in coordinate space so as to take properly
into account the continuum effect. The isovector peak induced by isoscalar
correlation, the isoscalar peak induced by isovector correlation, and the
possible collective states made by both isoscalar and isovector correlations,
("iS-iV pigmy resonance"), are shown. The strong neutron-proton interaction in
nuclei can be responsible for controlling the isospin structure of normal
modes. It is explicitly shown that in the scattering by isoscalar (isovector)
particles on NZ even-even nuclei isovector (isoscalar) strength in
addition to isoscalar (isovector) strength may be populated.Comment: 20 pages,7 figure
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