8,998 research outputs found
Spatial distribution of local density of states in vicinity of impurity on semiconductor surface
We present the results of detailed theoretical investigations of changes in
local density of total electronic surface states in 2D anisotropic atomic
semiconductor lattice in vicinity of impurity atom for a wide range of applied
bias voltage. We have found that taking into account changes in density of
continuous spectrum states leads to the formation of a downfall at the
particular value of applied voltage when we are interested in the density of
states above the impurity atom or even to a series of downfalls for the fixed
value of the distance from the impurity. The behaviour of local density of
states with increasing of the distance from impurity along the chain differs
from behaviour in the direction perpendicular to the chain.Comment: 6 pages, 5 figure
Quasielastic electron- and neutrino-nucleus scattering in a continuum random phase approximation approach
We present a continuum random phase approximation approach to study electron-
and neutrino-nucleus scattering cross sections, in the kinematic region where
quasielastic scattering is the dominant process. We show the validity of the
formalism by confronting inclusive () cross sections with the available
data. We calculate flux-folded cross sections for charged-current quasielastic
antineutrino scattering off C and compare them with the MiniBooNE
cross-section measurements. We pay special emphasis to the contribution of
low-energy nuclear excitations in the signal of accelerator-based
neutrino-oscillation experiments.Comment: 5 pages, 5 figures. Contribution to the proceedings of the 16th
International Workshop on Neutrino Factories and Future Neutrino Beam
Facilities (NUFACT-2014
Quasielastic contribution to antineutrino-nucleus scattering
We report on a calculation of cross sections for charged-current quasielastic
antineutrino scattering off C in the energy range of interest for the
MiniBooNE experiment. We adopt the impulse approximation (IA) and use the
nonrelativistic continuum random phase approximation (CRPA) to model the
nuclear dynamics. An effective nucleon-nucleon interaction of the Skyrme type
is used. We compare our results with the recent MiniBooNE antineutrino
cross-section data and confront them with alternate calculations. The CRPA
predictions reproduce the gross features of the shape of the measured
double-differential cross sections. The CRPA cross sections are typically
larger than those of other reported IA calculations but tend to underestimate
the magnitude of the MiniBooNE data. We observe that an enhancement of the
nucleon axial mass in CRPA calculations is an effective way of improving on the
description of the shape and magnitude of the double-differential cross
sections. The rescaling of is illustrated to affect the shape of the
double-differential cross sections differently than multinucleon effects beyond
the IA.Comment: 10 pages, 10 figures. Version published in Physical Review
Electron-neutrino scattering off nuclei from two different theoretical perspectives
We analyze charged-current electron-neutrino cross sections on Carbon. We
consider two different theoretical approaches, on one hand the Continuum Random
Phase Approximation (CRPA) which allows a description of giant resonances and
quasielastic excitations, on the other hand the RPA-based calculations which
are able to describe multinucleon emission and coherent and incoherent pion
production as well as quasielastic excitations. We compare the two approaches
in the genuine quasielastic channel, and find a satisfactory agreement between
them at large energies while at low energies the collective giant resonances
show up only in the CRPA approach. We also compare electron-neutrino cross
sections with the corresponding muon-neutrino ones in order to investigate the
impact of the different charged-lepton masses. Finally, restricting to the
RPA-based approach we compare the sum of quasielastic, multinucleon emission,
coherent and incoherent one-pion production cross sections (folded with the
electron-neutrino T2K flux) with the charged-current inclusive
electron-neutrino differential cross sections on Carbon measured by T2K. We
find a good agreement with the data. The multinucleon component is needed in
order to reproduce the T2K electron-neutrino inclusive cross sections
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