1,237 research outputs found
Comparison of Transfer-to-Continuum and Eikonal Models of Projectile Fragmentation Reactions
Spectroscopic properties of nuclei are accessible with projectile
fragmentation reactions, but approximations made in the reaction theory can
limit the accuracy of the determinations. We examine here two models that have
rather different approximations for the nucleon wave function, the target
interaction, and the treatment of the finite duration of the reaction. The
nucleon-target interaction is treated differently in the eikonal and the
transfer-to-continuum model, but the differences are more significant for light
targets. We propose a new parameterization with that in mind. We also propose a
new formula to calculate the amplitude that combines the better treatment of
the wave function in the eikonal model with the better treatment of the target
interaction in the transfer-to-continuum model.Comment: 21 pages, latex file including 3 tables. 5 figures. Submitted to
Phys. Rev.
Viscoelastic Multicomponent Fluids in confined Flow-Focusing Devices
The effects of elasticity on the break-up of liquid threads in microfluidic
cross-junctions is investigated using numerical simulations based on the
"lattice Boltzmann models" (LBM). Working at small Capillary numbers, we
investigate the effects of non-Newtonian phases in the transition from droplet
formation at the cross-junction (DCJ) and droplet formation downstream of the
cross-junction (DC) (Liu & Zhang, , 082101
(2011)). Viscoelasticity is found to influence the break-up point of the
threads, which moves closer to the cross-junction and stabilizes. This is
attributed to an increase of the polymer feedback stress forming in the corner
flows, where the side channels of the device meet the main channel.Comment: 4 pages, 2 figures, AIP Conference Proceedings, 201
Initial State Dependence of the Breakup of Weakly Bound Carbon Isotopes
The one-neutron nuclear breakup from the Carbon isotopes C and
C, is calculated as an example of application of the theory of transfer
to the continuum reactions in the formulation which includes spin coupling.
The effect of the energy sharing between the parallel and transverse neutron
momentum distributions is taken into account thus resulting in a theory which
is more general than sudden eikonal approaches. Both effects are necessary to
understand properly the breakup from not too weakly bound orbitals.
Breakup which leaves the core into an excited state below particle threshold is
also considered. The core-target interaction is treated in the smooth cut-off
approximation. By comparing to presently available experimental data we show
how to make some hypothesis on the quantum numbers and occupancy of the neutron
initial state. Possible ambiguities in the interpretation of inclusive cross
sections are discussed.Comment: 22 RevTeX pages,3 ps figures. Phys. Rev. C, accepte
Recommended from our members
Debundling and Selective Enrichment of SWNTs for Applications in Dye-Sensitized Solar Cells
We present an overview of the recent developments in de-bundling and sorting of Single-Wall Carbon Nanotubes (SWNTs), which are useful for hi-tech applications in dye sensitized solar cells (DSSCs). Applications of SWNTs as transparent and conductive films, catalyst, and scaffold in DSSCs are also reviewed.Peer Reviewe
Imaginary part of the C 9 â Be 9 single-folded optical potential
In a recent publication we have argued that using two very successful n\text{\ensuremath{-}}^{9}\mathrm{Be} optical potentials [A. Bonaccorso and R. J. Charity, Phys. Rev. C 89, 024619 (2014)] and microscopic projectile densities, it is possible to build a single-folded (light-) nucleus- imaginary optical potential which is more accurate than a double-folded optical potential. By comparing to experimental reaction cross sections, we showed for , and projectiles, that a very good agreement between theory and data could be obtained with such a ``bare'' potential, at all but the lowest energies where a small semimicroscopic surface term was added to the single-folded potential to take into account projectile breakup. In this paper we extend this study to the case of projectiles and assess the sensitivity to the projectile density used. We then obtained the modulus of the nucleus-nucleus matrix and parametrize it in terms of a strong-absorption radius and finally extracted the phenomenological energy dependence of this radius. This approach could be the basis for a systematic study of optical potentials for light exotic nuclei scattering on light targets and/or parametrizations of the matrix. Furthermore our study will serve to make a quantitative assessment of the description of the core-target part of knockout reactions, in particular their localization in terms of impact parameters
Ultrafast Carrier Recombination and Generation Rates for Plasmon Emission and Absorption in Graphene
Electron-hole generation and recombination rates for plasmon emission and
absorption in Graphene are presented. The recombination times of carriers due
to plasmon emission have been found to be in the tens of femtoseconds to
hundreds of picoseconds range. The recombination times depend sensitively on
the carrier energy, carrier density, temperature, and the plasmon dispersion.
Carriers near the Dirac point are found to have much longer lifetimes compared
to carriers at higher energies. Plasmons in a Graphene layer on a polar
substrate hybridize with the surface optical phonons and this hybridization
modifies the plasmon dispersion. We also present generation and recombination
rates of carriers due to plasmon emission and absorption in Graphene layers on
polar substrates.Comment: 7 Pages, 11 Figures, To appear in Phys. Rev. B (2011
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
- âŠ