14,215 research outputs found
New expression for the K-shell ionization
A new expression for the total K-shell ionization cross section by electron
impact based on the relativistic extension of the binary encounter Bethe (RBEB)
model, valid from ionization threshold up to relativistic energies, is
proposed. The new MRBEB expression is used to calculate the K-shell ionization
cross sections by electron impact for the selenium atom. Comparison with all,
to our knowledge, available experimental data shows good agreement
Building multi-layer social knowledge maps with google maps API
Google Maps is an intuitive online-map service which changes people's way of navigation on Geo-maps. People can explore the maps in a multi-layer fashion in order to avoid information overloading. This paper reports an innovative approach to extend the "power" of Google Maps to adaptive learning. We have designed and implemented a navigator for multi-layer social knowledge maps, namely ProgressiveZoom, with Google Maps API. In our demonstration, the knowledge maps are built from the Interactive System Design (ISD) course at the School of Information Science, University of Pittsburgh. Students can read the textbooks and reflect their individual and social learning progress in a context of pedagogical hierarchical structure
Surface terms on the Nishimori line of the Gaussian Edwards-Anderson model
For the Edwards-Anderson model we find an integral representation for some
surface terms on the Nishimori line. Among the results are expressions for the
surface pressure for free and periodic boundary conditions and the adjacency
pressure, i.e., the difference between the pressure of a box and the sum of the
pressures of adjacent sub-boxes in which the box can been decomposed. We show
that all those terms indeed behave proportionally to the surface size and prove
the existence in the thermodynamic limit of the adjacency pressure.Comment: Final version with minor corrections. To appear in Journal of
Statistical Physic
Shapes and beta decay in proton rich Ge, Se, Kr and Sr isotopes
We study ground states and beta decay properties of the proton rich isotope
chains Ge, Se, Kr, and Sr. We use a deformed selfconsistent HF+RPA approach
with density-dependent effective interactions of Skyrme type. We find that most
of the isotopes present two HF minima corresponding to two different shapes. In
addition to static quadrupole moments and other ground state band properties,
we present results for Gamow-Teller strength distributions, as well as for
half-lives and summed strengths. The role of deformation is particularly
emphasized.Comment: 29 pages Revtex, 19 PS figures, to appear in Nucl. Phys.
The Ising-Sherrington-Kirpatrick model in a magnetic field at high temperature
We study a spin system on a large box with both Ising interaction and
Sherrington-Kirpatrick couplings, in the presence of an external field. Our
results are: (i) existence of the pressure in the limit of an infinite box.
When both Ising and Sherrington-Kirpatrick temperatures are high enough, we
prove that: (ii) the value of the pressure is given by a suitable replica
symmetric solution, and (iii) the fluctuations of the pressure are of order of
the inverse of the square of the volume with a normal distribution in the
limit. In this regime, the pressure can be expressed in terms of random field
Ising models
Nuclear structure calculations for two-neutrino double-beta decay
We study the two-neutrino double-beta decay in 76Ge, 116Cd, 128Te, 130Te, and
150Nd, as well as the two Gamow-Teller branches that connect the double-beta
decay partners with the states in the intermediate nuclei. We use a theoretical
microscopic approach based on a deformed selfconsistent mean field with Skyrme
interactions including pairing and spin-isospin residual forces, which are
treated in a proton-neutron quasiparticle random-phase approximation. We
compare our results for Gamow-Teller strength distributions with experimental
information obtained from charge-exchange reactions. We also compare our
results for the two-neutrino double-beta decay nuclear matrix elements with
those extracted from the measured half-lives. Both single-state and
low-lying-state dominance hypotheses are analyzed theoretically and
experimentally making use of recent data from charge-exchange reactions and
beta decay of the intermediate nuclei.Comment: 11 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1502.0588
Gamow-Teller strength distributions in Fe and Ni stable isotopes
We study Gamow-Teller strength distributions in some selected nuclei of
particular Astrophysical interest within the iron mass region. The theoretical
framework is based on a proton-neutron Quasiparticle Random Phase Approximation
built on a deformed selfconsistent mean field basis obtained from two-body
density-dependent Skyrme forces. We compare our results to available
experimental information obtained from (n,p) and (p,n) charge exchange
reactions.Comment: 11 pages, 3 figure
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