2,323 research outputs found
Strong coupling effects in near-barrier heavy-ion elastic scattering
Accurate elastic scattering angular distribution data measured at bombarding
energies just above the Coulomb barrier have shapes that can markedly differ
from or be the same as the expected classical Fresnel scattering pattern
depending on the structure of the projectile, the target or both. Examples are
given such as 18O + 184W and 16O + 148,152Sm where the expected rise above
Rutherford scattering due to Coulomb-nuclear interference is damped by coupling
to the target excited states, and the extreme case of 11Li scattering, where
coupling to the 9Li + n + n continuum leads to an elastic scattering shape that
cannot be reproduced by any standard optical model parameter set. The recent
availability of high quality 6He, 11Li and 11Be data provides further examples
of the influence that coupling effects can have on elastic scattering.
Conditions for strong projectile-target coupling effects are presented with
special emphasis on the importance of the beam-target charge combination being
large enough to bring about the strong coupling effects. Several measurements
are proposed that can lead to further understanding of strong coupling effects
by both inelastic excitation and nucleon transfer on near-barrier elastic
scattering. A final note on the anomalous nature of 8B elastic scattering is
presented as it possesses a more or less normal Fresnel scattering shape
whereas one would a priori not expect this due to the very low breakup
threshold of 8B. The special nature of 11Li is presented as it is predicted
that no matter how far above the Coulomb barrier the elastic scattering is
measured, its shape will not appear as Fresnel like whereas the elastic
scattering of all other loosely bound nuclei studied to date should eventually
do so as the incident energy is increased, making both 8B and 11Li truly
"exotic".Comment: Review articl
Calculations of three-body observables in ^8B breakup
We discuss calculations of three-body observables for the breakup of ^8B on a
^{58}Ni target at low energy using the coupled discretised continuum channels
approach. Calculations of both the angular distribution of the ^7Be fragments
and their energy distributions are compared with those measured at several
laboratory angles. In these observables there is interference between the
breakup amplitudes from different spin-parity excitations of the projectile.
The resulting angle and the energy distributions reveal the importance of the
higher-order continuum state couplings for an understanding of the
measurements.Comment: 22 pages (postscript), accepted in Phys. Rev.
Recommended from our members
Influence of the microvasculature on oxygen transport in human brain tissue
This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.Two numerical methods are presented for simulating a micro-stroke: a discretised model and a continuum model, both developed for simulating coupled flow and oxygen transport to the microvasculature. The discrete model treats the microvasculature and the tissue perfusion as two coupled sub-systems governed by Poiseulle flow and mass transport equation respectively. The continuum model regards the blood passage
as a porous media flow and deals with mass transport in terms of a two phase flow system. In our simulations, it has been shown that the microvascular structure has a strong influence on the localized oxygen transport behaviour, contributing to more complex patterns in the tissue oxygen concentration than those found by assuming continuum behaviour
The low-lying spectrum of N=1 supersymmetric Yang-Mills theory
The spectrum of the lightest bound states in N=1 supersymmetric Yang-Mills
theory with SU(2) gauge group, calculated on the lattice, is presented. The
masses have first been extrapolated towards vanishing gluino mass and then to
the continuum limit. The final picture is consistent with the formation of
degenerate supermultiplets.Comment: 6 pages; 3 figures; proceedings of the EPS-HEP Conference 2015, 22-29
July 2015, Vienna, Austri
Open issues in extracting nuclear structure information from the breakup of exotic nuclei
The open issues in the development of models for the breakup of exotic nuclei
and the link with the extraction of structure information from experimental
data are reviewed. The question of the improvement of the description of exotic
nuclei within reaction models is approached in the perspective of previous
analyses of the sensitivity of these models to that description. Future
developments of reaction models are suggested, such as the inclusion of various
channels within one model. The search for new reaction observables that can
emphasise more details of exotic nuclear structure is also proposed.Comment: 18 pages, 4 figures, submitted as a contribution to the Secial Issue
on "Nuclear reaction theory" of the Journal of Physics G, guest edited by
R.C. Johnson and F.M. Nune
Simulating the scalar glueball on the lattice
Techniques for efficient computation of the scalar glueball mass on the
lattice are described. Directions and physics goals of proposed future
calculations will be outlined.Comment: 9 pages, 3 figures, submitted to the proceedings of the SUNYIT Scalar
Mesons workshop (May 2003
A parallel interaction potential approach coupled with the immersed boundary method for fully resolved simulations of deformable interfaces and membranes
In this paper we show and discuss the use of a versatile interaction
potential approach coupled with an immersed boundary method to simulate a
variety of flows involving deformable bodies. In particular, we focus on two
kinds of problems, namely (i) deformation of liquid-liquid interfaces and (ii)
flow in the left ventricle of the heart with either a mechanical or a natural
valve. Both examples have in common the two-way interaction of the flow with a
deformable interface or a membrane. The interaction potential approach (de
Tullio & Pascazio, Jou. Comp. Phys., 2016; Tanaka, Wada and Nakamura,
Computational Biomechanics, 2016) with minor modifications can be used to
capture the deformation dynamics in both classes of problems. We show that the
approach can be used to replicate the deformation dynamics of liquid-liquid
interfaces through the use of ad-hoc elastic constants. The results from our
simulations agree very well with previous studies on the deformation of drops
in standard flow configurations such as deforming drop in a shear flow or a
cross flow. We show that the same potential approach can also be used to study
the flow in the left ventricle of the heart. The flow imposed into the
ventricle interacts dynamically with the mitral valve (mechanical or natural)
and the ventricle which are simulated using the same model. Results from these
simulations are compared with ad- hoc in-house experimental measurements.
Finally, a parallelisation scheme is presented, as parallelisation is
unavoidable when studying large scale problems involving several thousands of
simultaneously deforming bodies on hundreds of distributed memory computing
processors
- …