4,995 research outputs found
Geometry of Borromean Halo Nuclei
We discuss the geometry of the highly quantal nuclear three-body systems
composed of a core plus two loosely bound particles. These Borromean nuclei
have no single bound two-body subsystem. Correlation plays a prominent role.
From consideration of the value extracted from electromagnetic
dissociation, in conjunction with HBT-type analysis of the two valence-halo
particles correlation, we show that an estimate of the over-all geometry can be
deduced. In particular we find that the opening angle between the two neutrons
in He and Li are, respectively, and . These angles are
reduced by about 12% to and
if the laser spectroscopy values of the rms charge
radii are used to obtain the rms distance between the cores and the center of
mass of the two neutrons. The opening angle in the case of Li is more
than 20% larger than recently reported by Nakamura \cite{Nak06}. The analysis
is extended to Be and the two-proton Borromean nucleus Ne where
complete data is still not available. Using available experimental data and
recent theoretical calculations we find,
and , respectively.Comment: 5 pages, one figure, version to appear in PRC, Rapid Communication
Exit Doorway Model for Nuclear Breakup of Weakly Bound Projectiles
We derive closed expressions for the nuclear breakup cross sections in the
adiabatic limit using the Austern-Blair theory. These expressions are
appropriate for the breakup of weakly bound nuclei. The concept of an exit
doorway that mediates the coupling between the entrance channel and the breakup
continuum is used. We prove the validity of the scaling law that dictates that
the nuclear breakup cross section scales linearly with the radius of the
target. We also compare our results for the nuclear breakup cross section of
Be, B on several targets with recent CDCC calculation.Comment: 5 pages, 1 figur
The Coulomb phase shift revisited
We investigate the Coulomb phase shift, and derive and analyze new and more
precise analytical formulae. We consider next to leading order terms to the
Stirling approximation, and show that they are important at small values of the
angular momentum and other regimes. We employ the uniform approximation.
The use of our expressions in low energy scattering of charged particles is
discussed and some comparisons are made with other approximation methods.Comment: 13 pages, 5 figures, 1 tabl
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