601 research outputs found
Anomalous population of He states in reactions with Li
Structure with the lowest energy observed in the He spectrum populated
in the proton knockout reaction with Li beam has a peak at
MeV. This peak is usually interpreted as a resonant ground state of
He. Our theoretical calculations indicate that this peak is likely to be
a pileup of , , and excitations with very similar shapes. %We
predict a very specific nature of the excitation in He. Moreover,
the ``soft'' excitation appears to be the lowest one in energy. Such an
anomalous continuum response is traced to the halo structure of Li
providing extreme low energy shift to all the expected continuum excitations.
Competitions of the initial state structure (ISS) and the final state
interaction (FSI) effects on the spectrum and three-body correlations in
He are discussed. Analogous effect of the extreme low-energy shift could
also be expected in other cases of emitters populated in reactions with
halo nuclei. Simplified example of the He spectrum in knockout
from Be, is given. We also discuss limits on the properties of He
stemming from the observed He spectrum.Comment: 10 pages, 13 figure
Two-proton radioactivity and three-body decay. V. Improved momentum distributions
Nowadays quantum-mechanical theory allows one to reliably calculate the
processes of 2p radioactivity (true three-body decays) and the corresponding
energy and angular correlations up to distances of the order of 1000 fm.
However, the precision of modern experiments has now become sufficient to
indicate some deficiency of the predicted theoretical distributions. In this
paper we discuss the extrapolation along the classical trajectories as a method
to improve the convergence of the theoretical energy and angular correlations
at very large distances (of the order of atomic distances), where only the
long-range Coulomb forces are still operating. The precision of this approach
is demonstrated using the "exactly" solvable semianalytical models with
simplified three-body Hamiltonians. It is also demonstrated that for heavy 2p
emitters, the 2p decay momentum distributions can be sensitive to the effect of
the screening by atomic electrons. We compare theoretical results with
available experimental data.Comment: 13 pages, 18 figure
From Coulomb excitation cross sections to non-resonant astrophysical rates in three-body systems: Ne case
Coulomb and nuclear dissociation of Ne on light and heavy targets are
studied theoretically. The dipole E1 strength function is determined in a broad
energy range including energies of astrophysical interest. Dependence of the
strength function on different parameters of the Ne ground state
structure and continuum dynamics is analyzed in a three-body model. The
discovered dependence plays an important role for studies of the strength
functions for the three-body E1 dissociation and radiative capture. The
constraints on the configuration mixing in Ne and on
-wave interaction in the O+ channel are imposed based on
experimental data for Ne Coulomb dissociation on heavy target.Comment: 12 pages, 13 figure
Interactive forms in the process of teaching bachelors at the university
The article considers the possibilities of using interactive forms of training in the process of preparing bachelorsРассматриваются возможности использования интерактивных форм обучения в процессе подготовки бакалавро
A Paley-Wiener Theorem for Periodic Scattering with Applications to the Korteweg-de Vries Equation
A one-dimensional SchrÄodinger operator which is a short-range perturbation of a finite-gap operator is considered. There are given the necessary and su±cient conditions on the left/right reflection coeffcient such that the difference of the potentials has finite support to the left/right, respectively. Moreover, these results are applied to show a unique continuation type result for solutions of the Korteweg{de Vries equation in this context. By virtue of the Miura transform an analogous result for the modified Korteweg-de Vries equation is also obtained
Trace Formulas in Connection with Scattering Theory for Quasi-Periodic Background
We investigate trace formulas for Jacobi operators which are trace class
perturbations of quasi-periodic finite-gap operators using Krein's spectral
shift theory. In particular we establish the conserved quantities for the
solutions of the Toda hierarchy in this class.Comment: 7 page
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