3,012 research outputs found
Non-adiabatic corrections to elastic scattering of halo nuclei
We derive the formalism for the leading order corrections to the adiabatic
approximation to the scattering of composite projectiles. Assuming a two-body
projectile of core plus loosely-bound valence particle and a model (the core
recoil model) in which the interaction of the valence particle and the target
can be neglected, we derive the non-adiabatic correction terms both exactly,
using a partial wave analysis, and using the eikonal approximation. Along with
the expected energy dependence of the corrections, there is also a strong
dependence on the valence-to-core mass ratio and on the strength of the
imaginary potential for the core-target interaction, which relates to
absorption of the core in its scattering by the target. The strength and
diffuseness of the core-target potential also determine the size of the
corrections. The first order non-adiabatic corrections were found to be smaller
than qualitative estimates would expect. The large absorption associated with
the core-target interaction in such halo nuclei as Be11 kills off most of the
non-adiabatic corrections. We give an improved estimate for the range of
validity of the adiabatic approximation when the valence-target interaction is
neglected, which includes the effect of core absorption. Some consideration was
given to the validity of the eikonal approximation in our calculations.Comment: 14 pages with 10 figures, REVTeX4, AMS-LaTeX v2.13, submitted to
Phys. Rev.
One-neutron halo structure by the ratio method
We present a new observable to study halo nuclei. This new observable is a
particular ratio of angular distributions for elastic breakup and scattering.
For one-neutron halo nuclei, it is shown to be independent of the reaction
mechanism and to provide significant information about the structure of the
projectile, including binding energy, partial-wave configuration, and radial
wave function of the halo. This observable offers new capabilities for the
study of nuclear structure far from stability.Comment: 9 pages, 4 figure
Nature of the Missing Near-side Amplitude in Calculations of Intermediate Energy (d,p) and (p,d) Reactions
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
Forbidden transitions in the helium atom
Nonrelativistically forbidden, single-photon transition rates between low
lying states of the helium atom are rigorously derived within quantum
electrodynamics theory. Equivalence of velocity and length gauges, including
relativistic corrections is explicitly demonstrated. Numerical calculations of
matrix elements are performed with the use of high precision variational wave
functions and compared to former results.Comment: 11 pages, 1 figure, submitted to Phys. Rev.
The influence of chop location on pork loin quality
Pork longissimus muscle quality characteristics were evaluated on 109 center cut boneless loins. After 21 d aging, loins were cut into 1-inch chops and allowed to bloom for 30 minutes before visual measurements (color, marbling and firmness) and instrumental color were recorded for each chop. Overall, visual color was the lightest on the anterior and posterior ends and was the darkest from approximately 50% to 80% of the length of the loin. Marbling was the highest at the posterior end, lowest in mid-loin, then higher toward the anterior end. Loins were the softest at the anterior end and became firmer toward the posterior end. From the anterior to approximately 40-
50% of the loin length, chops became darker
(lower L*), redder (higher a*), and less yellow (lower b*). Near the center of the loin, color was constant, but became lighter (higher L*) and more yellow (higher b*) at the posterior end. Chops located at 25% (anterior), 50% (middle) and 75% (posterior) of the length of each loin were collected and further analyzed. Section chops within loins had similar pH values. The chop from the anterior section contained the highest percentage of crude fat, followed by the posterior section chop, and the middle section chop contained the lowest percentage.
The middle section chop contained the highest percentage of moisture. The posterior
section chop had more moisture display loss than the anterior and middle section chops. The anterior section chop had more cooking loss than the posterior section chop. Chops became progressively less tender the more posterior the section location
Addition Spectra of Quantum Dots in Strong Magnetic Fields
We consider the magnetic field dependence of the chemical potential for
parabolically confined quantum dots in a strong magnetic field. Approximate
expressions based on the notion that the size of a dot is determined by a
competition between confinement and interaction energies are shown to be
consistent with exact diagonalization studies for small quantum dots. Fine
structure is present in the magnetic field dependence which cannot be explained
without a full many-body description and is associated with ground-state level
crossings as a function of confinement strength or Zeeman interaction strength.
Some of this fine structure is associated with precursors of the bulk
incompressible states responsible for the fractional quantum Hall effect.Comment: 11 pages, 3 figures (available from [email protected]). Revtex
3.0. (IUCM93-010
Universal Holographic Chiral Dynamics in an External Magnetic Field
In this work we further extend the investigation of holographic gauge
theories in external magnetic fields, continuing earlier work. We study the
phenomenon of magnetic catalysis of mass generation in 1+3 and 1+2 dimensions,
using D3/D7- and D3/D5-brane systems, respectively. We obtain the low energy
effective actions of the corresponding pseudo Goldstone bosons and study their
dispersion relations. The D3/D7 system exhibits the usual
Gell-Mann--Oakes--Renner (GMOR) relation and a relativistic dispersion
relation, while the D3/D5 system exhibits a quadratic non-relativistic
dispersion relation and a modified linear GMOR relation. The low energy
effective action of the D3/D5 system is related to that describing magnon
excitations in a ferromagnet. We also study properties of general Dp/Dq systems
in an external magnetic field and verify the universality of the magnetic
catalysis of dynamical symmetry breaking.Comment: 41 pages, 11 figures, references adde
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