152 research outputs found
Complementary reaction analyses and the isospin mixing of the 4- states in 16O
Data from the inelastic scattering of electrons, and of intermediate energy
protons and pions leading to ``stretched'' configuration 4- states near 19 MeV
excitation in 16O as well as from charge exchange (p,n) scattering to an
isobaric analogue (4-) state in 16F have been analyzed to ascertain the degree
of isospin mixing contained within those states and of the amount of
d_{5/2}-p_{3/2}^{-1} particle-hole excitation strength they exhaust. The
electron and proton scattering data have been analyzed using microscopic models
of the structure and reactions, with details constrained by analyses of elastic
scattering data.Comment: 25 pages, 12 figure
Is friction responsible for the reduction of fusion rates far below the Coulomb barrier?
The fusion of two interacting heavy ions traditionally has been interpreted
in terms of the penetration of the projectile into the target. Observed rates
well below the Coulomb barrier are considerably lower than estimates obtained
from penetration factors. One approach in the analysis of the data invokes
coupling to non-elastic channels in the scattering as the source of the
depletion. Another is to analyze those data in terms of tunneling in
semi-classical models, with the observed depletion being taken as evidence of a
``friction'' under the barrier. A complementary approach is to consider such
tunneling in terms of a fully quantal model. We investigate tunneling with both
one-dimensional and three-dimensional models in a fully quantal approach to
investigate possible sources for such a friction. We find that the observed
phenomenon may not be explained by friction. However, we find that under
certain conditions tunneling may be enhanced or diminished by up to 50%, which
finds analogy with observation, without the invocation of a friction under the
barrier.Comment: 18 pages, 15 figures embedde
Total reaction cross sections for neutron-nucleus scattering
Neutron total reaction cross sections at 45, 50, 55, 60, 65, and 75 MeV from
nuclei 12C, 28Si, 56Fe, 90Zr, and 208Pb have been measured and are compared
with (microscopic) optical model predictions. The optical potentials were
obtained in coordinate space by full folding effective nucleon-nucleon
interactions with realistic nuclear ground state density matrices. Good to
excellent agreement is found.Comment: 5 pages, 1 figure, RevTeX
- …