185 research outputs found
Halo Excitation of He in Inelastic and Charge-Exchange Reactions
Four-body distorted wave theory appropriate for nucleon-nucleus reactions
leading to 3-body continuum excitations of two-neutron Borromean halo nuclei is
developed. The peculiarities of the halo bound state and 3-body continuum are
fully taken into account by using the method of hyperspherical harmonics. The
procedure is applied for A=6 test-bench nuclei; thus we report detailed studies
of inclusive cross sections for inelastic He(p,p')He and
charge-exchange Li(n,p)He reactions at nucleon energy 50 MeV. The
theoretical low-energy spectra exhibit two resonance-like structures. The first
(narrow) is the excitation of the well-known three-body resonance. The
second (broad) bump is a composition of overlapping soft modes of
multipolarities whose relative weights depend on
transferred momentum and reaction type. Inelastic scattering is the most
selective tool for studying the soft dipole excitation mode.Comment: Submitted to Phys. Rev. C., 11 figures using eps
Computations of Three-Body Continuum Spectra
We formulate a method to solve the coordinate space Faddeev equations for
positive energies. The method employs hyperspherical coordinates and analytical
expressions for the effective potentials at large distances. Realistic
computations of the parameters of the resonances and the strength functions are
carried out for the Borromean halo nucleus 6He (n+n+alpha) for J = 0+, 0-, 1+,
1-, 2+,2-. PACS numbers: 21.45.+v, 11.80.Jy, 31.15.Ja, 21.60.GxComment: 10 pages, 3 postscript figures, LaTeX, epsf.sty, corrected misprints
in the caption of Fig.
Three-body continuum energy correlations in Borromean halo nuclei. III. Short-range external fields
Excitations in the Halo Nucleus He-6 Following The Li-7(gamma,p)He-6 Reaction
A broad excited state was observed in 6-He with energy E_x = 5 +/- 1 MeV and
width Gamma = 3 +/- 1 MeV, following the reaction Li-7(gamma,p)He-6. The state
is consistent with a number of broad resonances predicted by recent cluster
model calculations. The well-established reaction mechanism, combined with a
simple and transparent analysis procedure confers considerable validity to this
observation.Comment: 3 pages of LaTeX, 3 figures in PostScript, approved for publication
in Phys. Rev. C, August, 200
НЕОБЫЧНОЕ ИНОРОДНОЕ ТЕЛО НОСА
ABSTRACT. The authors present the clinic case: rare traumatic injury of the face with the big foreign body in the nose as a knife. РЕЗЮМЕ. Авторы представляют случай из практики: редкое травматическое повреждение лица с наличием в носу крупного инородного тела в виде ножа
Three-body resonances in He-6, Li-6, and Be-6, and the soft dipole mode problem of neutron halo nuclei
Using the complex scaling method, the low-lying three-body resonances of
He, Li, and Be are investigated in a parameter-free microscopic
three-cluster model. In He a 2, in Li a 2 and a 1, and in
Be the 0 ground state and a 2 excited state is found. The other
experimentally known 2 state of Li cannot be localized by our present
method. We have found no indication for the existence of the predicted 1
soft dipole state in He. We argue that the sequential decay mode of He
through the resonant states of its two-body subsystem can lead to peaks in the
excitation function. This process can explain the experimental results in the
case of Li, too. We propose an experimental analysis, which can decide
between the soft dipole mode and the sequential decay mode.Comment: REVTEX, Submitted to Phys. Rev. C, 12 pages, 2 postscript figures are
available upon request. CALTECH, MAP-16
Total Photoabsorption Cross Sections of A=6 Nuclei with Complete Final State Interaction
The total photoabsorption cross sections of 6He and 6Li are calculated
microscopically with full inclusion of the six-nucleon final state interaction
using semirealistic nucleon-nucleon potentials. The Lorentz Integral Transform
(LIT) method and the effective interaction approach for the hyperspherical
formalism are employed. While 6Li has a single broad giant resonance peak,
there are two well separated peaks for 6He corresponding to the breakup of the
neutron halo and the alpha core, respectively. The comparison with the few
available experimental data is discussed.Comment: LaTeX, 8 pages, 3 ps figure
Comment on ``Large-space shell-model calculations for light nuclei''
In a recent publication Zheng, Vary, and Barrett reproduced the negative
quadrupole moment of Li-6 and the low-lying positive-parity states of He-5 by
using a no-core shell model. In this Comment we question the meaning of these
results by pointing out that the model used is inadequate for the reproduction
of these properties.Comment: Latex with Revtex, 1 postscript figure in separate fil
- …