56 research outputs found
Probing nuclear skins and halos with elastic electron scattering
I investigate the elastic electron scattering off nuclei far from the
stability line. The effects of the neutron and proton skins and halos on the
differential cross sections are explored. Examples are given for the charge
distribution in Sn isotopes and its relation to the neutron skin. The neutron
halo in Li and the proton halo in B are also investigated.
Particular interest is paid to the inverse scattering problem and its
dependence on the experimental precision. These studies are of particular
interest for the upcoming electron ion colliders at the GSI and RIKEN
facilities.Comment: 27 pages, 9 figures, accepted for publication in J. Phys.
Nuclear Charge Density Distributions from Elastic Electron Scattering Data
The model independent procedure of extracting charge density distributions
from elastic electron scattering data is investigated. The charge density
distributions are expanded on an orthonormal basis and the parameters of the
expansions are fixed by the comparison with the experimental data. Two bases
with different analytical properties (Fourier-Bessel and Hermite) are used.
This allows us to disentangle the uncertainties coming from the choice of the
expansion basis from those intrinsic to the extraction procedure. We design a
set of tests to select the number of the expansion coefficients adequate for a
proper description of the data. The procedure is applied to elastic data
measured on C, Ca and Pb nuclei.Comment: 17 pages, 11 figures available on request to [email protected], to
be published in Nucl.Phy
Systematical Approach to the Exact Solution of the Dirac Equation for A Special Form of the Woods-Saxon Potential
Exact solution of the Dirac equation for a special form of the Woods-Saxon
potential is obtained for the s-states. The energy eigenvalues and
two-component spinor wave functions are derived by using a systematical method
which is called as Nikiforov-Uvarov. It is seen that the energy eigenvalues
strongly depend on the potential parameters. In addition, it is also shown that
the non-relativistic limit can be reached easily and directly.Comment: 10 pages, no figures, submitted for Publicatio
The one-body and two-body density matrices of finite nuclei with an appropriate treatment of the center-of-mass motion
The one-body and two-body density matrices in coordinate space and their
Fourier transforms in momentum space are studied for a nucleus (a
nonrelativistic, self-bound finite system). Unlike the usual procedure,
suitable for infinite or externally bound systems, they are determined as
expectation values of appropriate intrinsic operators, dependent on the
relative coordinates and momenta (Jacobi variables) and acting on intrinsic
wavefunctions of nuclear states. Thus, translational invariance (TI) is
respected. When handling such intrinsic quantities, we use an algebraic
technique based upon the Cartesian representation, in which the coordinate and
momentum operators are linear combinations of the creation and annihilation
operators a^+ and a for oscillator quanta. Each of the relevant multiplicative
operators can then be reduced to the form: one exponential of the set {a^+}
times other exponential of the set {a}. In the course of such a normal-ordering
procedure we offer a fresh look at the appearance of "Tassie-Barker" factors,
and point out other model-independent results. The intrinsic wavefunction of
the nucleus in its ground state is constructed from a
nontranslationally-invariant (nTI) one via existing projection techniques. As
an illustration, the one-body and two-body momentum distributions (MDs) for the
4He nucleus are calculated with the Slater determinant of the
harmonic-oscillator model as the trial, nTI wavefunction. We find that the TI
introduces important effects in the MDs.Comment: 13 pages, incl. 3 figures - to appear in Eur. Phys. J.
Systematic study of the effect of short range correlations on the form factors and densities of s-p and s-d shell nuclei
Analytical expressions of the one- and two-body terms in the cluster
expansion of the charge form factors and densities of the s-p and s-d shell
nuclei with N=Z are derived. They depend on the harmonic oscillator parameter b
and the parameter which originates from the Jastrow correlation
function. These expressions are used for the systematic study of the effect of
short range correlations on the form factors and densities and of the mass
dependence of the parameters b and . These parameters have been
determined by fit to the experimental charge form factors. The inclusion of the
correlations reproduces the experimental charge form factors at the high
momentum transfers (). It is found that while the parameter
is almost constant for the closed shell nuclei, He, O and
Ca, its values are larger (less correlated systems) for the open shell
nuclei, indicating a shell effect in the closed shell nuclei.Comment: Latex, 21 pages, 6 figures, 1 tabl
The FLUKA atmospheric neutrino flux calculation
The 3-dimensional (3-D) calculation of the atmospheric neutrino flux by means
of the FLUKA Monte Carlo model is here described in all details, starting from
the latest data on primary cosmic ray spectra. The importance of a 3-D
calculation and of its consequences have been already debated in a previous
paper. Here instead the focus is on the absolute flux. We stress the relevant
aspects of the hadronic interaction model of FLUKA in the atmospheric neutrino
flux calculation. This model is constructed and maintained so to provide a high
degree of accuracy in the description of particle production. The accuracy
achieved in the comparison with data from accelerators and cross checked with
data on particle production in atmosphere certifies the reliability of shower
calculation in atmosphere. The results presented here can be already used for
analysis by current experiments on atmospheric neutrinos. However they
represent an intermediate step towards a final release, since this calculation
does not yet include the bending of charged particles in atmosphere. On the
other hand this last aspect, while requiring a considerable effort in a fully
3-D description of the Earth, if a high level of accuracy has to be maintained,
does not affect in a significant way the analysis of atmospheric neutrino
events.Comment: Papper has been corrected since the cosine of Zenith angle in flux
tables was erraneously inverted. Also, fig. 17 and 18 have been correcte
Improved Nearside-Farside Decomposition of Elastic Scattering Amplitudes
A simple technique is described, that provides improved nearside-farside (NF)
decompositions of elastic scattering amplitudes. The technique, involving the
resummation of a Legendre partial wave series, reduces the importance of
unphysical contributions to NF subamplitudes, which can arise in more
conventional NF decompositions. Applications are made to a strong absorption
model and to a O + C optical potential at
MeV.Comment: 5 pages, 2 figure
Universal trend of the information entropy of a fermion in a mean field
We calculate the information entropy of single-particle states in
position-space and momentum-space for a nucleon in a nucleus, a
particle in a hypernucleus and an electron in an atomic cluster. It
is seen that and obey the same approximate functional form as
functions of the number of particles, ({\rm or}
in all of the above many-body systems in position- and momentum- space
separately. The net information content is a slowly varying
function of of the same form as above. The entropy sum is
invariant to uniform scaling of coordinates and a characteristic of the
single-particle states of a specific system. The order of single-particle
states according to is the same as their classification according to
energy keeping the quantum number constant. The spin-orbit splitting is
reproduced correctly. It is also seen that enhances with
excitation of a fermion in a quantum-mechanical system. Finally, we establish a
relationship of with the energy of the corresponding single-particle
state i.e. . This relation holds for all the
systems under consideration.Comment: 9 pages, latex, 6 figure
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