69 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.
Monte Carlo integration in Glauber model analysis of reactions of halo nuclei
Reaction and elastic differential cross sections are calculated for light
nuclei in the framework of the Glauber theory. The optical phase-shift function
is evaluated by Monte Carlo integration. This enables us to use the most
accurate wave functions and calculate the phase-shift functions without
approximation. Examples of proton nucleus (e.g. p-He, p-Li) and
nucleus-nucleus (e.g. HeC) scatterings illustrate the effectiveness
of the method. This approach gives us a possibility of a more stringent
analysis of the high-energy reactions of halo nuclei.Comment: 20 pages, 8 figure
Non-diffractive mechanisms in the meson photoproduction on nucleons
We examine the non-diffractive mechanisms in the meson photoproduction
from threshold up to a few GeV using an effective Lagrangian in a constituent
quark model. The new data from CLAS at large angles can be consistently
accounted for in terms of {\it s}- and {\it u}-channel processes. Isotopic
effects arising from the reactions and , are investigated by comparing the cross sections and polarized beam
asymmetries. Our result highlights an experimental means of studying
non-diffractive mechanisms in meson photoproduction.Comment: 4 eps figures, version accepted by Phys. Lett.
Coulomb and nuclear breakup effects in the single neutron removal reaction 197Au(17C,16C gamma)X
We analyze the recently obtained new data on the partial cross sections and
parallel momentum distributions for transitions to ground as well as excited
states of the 16C core, in the one-neutron removal reaction 197Au(17C,16C
gamma)X at the beam energy of 61 MeV/nucleon. The Coulomb and nuclear breakup
components of the one-neutron removal cross sections have been calculated
within a finite range distorted wave Born approximation theory and an eikonal
model, respectively. The nuclear contributions dominate the partial cross
sections for the core excited states. By adding the nuclear and Coulomb cross
sections together, a reasonable agreement is obtained with the data for these
states. The shapes of the experimental parallel momentum distributions of the
core states are described well by the theory.Comment: Revtex format, two figures included, to appear in Phys. Rev. C.
(Rapid communications
Radiative capture and electromagnetic dissociation involving loosely bound nuclei: the B example
Electromagnetic processes in loosely bound nuclei are investigated using an
analytical model. In particular, electromagnetic dissociation of B is
studied and the results of our analytical model are compared to numerical
calculations based on a three-body picture of the B bound state. The
calculation of energy spectra is shown to be strongly model dependent. This is
demonstrated by investigating the sensitivity to the rms intercluster distance,
the few-body behavior, and the effects of final state interaction. In contrast,
the fraction of the energy spectrum which can be attributed to E1 transitions
is found to be almost model independent at small relative energies. This
finding is of great importance for astrophysical applications as it provides us
with a new tool to extract the E1 component from measured energy spectra. An
additional, and independent, method is also proposed as it is demonstrated how
two sets of experimental data, obtained with different beam energy and/or
minimum impact parameter, can be used to extract the E1 component.Comment: Submitted to Phys. Rev. C. 10 pages, 7 figure
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