11 research outputs found
Quadrupole moments of odd-odd near-magic nuclei
Ground state quadrupole moments of odd-odd near double magic nuclei are
calculated in the approximation of no interaction between odd particles. Under
such a simple approximation, the problem is reduced to the calculations of
quadrupole moments of corresponding odd-even nuclei. These calculations are
performed within the self-consistent Theory of Finite Fermi Systems based on
the Energy Density Functional by Fayans et al. with the known DF3-a parameters.
A reasonable agreement with the available experimental data has been obtained
for odd-odd nuclei and odd near-magic nuclei investigated. The self-consistent
approach under consideration allowed us to predict the unknown quadrupole
moments of odd-even and odd-odd nuclei near the double-magic Ni,
Sn ones.Comment: 3 pages, Poster presented at International Conference on Nuclear
Structure and Related Topics, Dubna, July 2-7, 201
Magnetic moments of odd-odd spherical nuclei
Magnetic moments of more than one hundred odd-odd spherical nuclei in ground
and excited states are calculated within the self-consistent TFFS based on the
EDF method by Fayans {\it et al}. We limit ourselves to nuclei with a neutron
and a proton particle (hole) added to the magic or semimagic core. A simple
model of no interaction between the odd nucleons is used. In most the cases we
analyzed, a good agreement with the experimental data is obtained. Several
cases are considered where this simple model does not work and it is necessary
to go beyond. The unknown values of magnetic moments of many unstable odd and
odd-odd nuclei are predicted including sixty values for excited odd-odd nuclei.Comment: 10 page
Phonon coupling effects in magnetic moments of magic and semi-magic nuclei
Phonon coupling (PC) corrections to magnetic moments of odd neighbors of
magic and semi-magic nuclei are analyzed within the self-consistent Theory of
Finite Fermi Systems (TFFS) based on the Energy Density Functional by Fayans et
al. The perturbation theory in g_L^2 is used where g_L is the phonon-particle
coupling vertex. A model is developed with separating non-regular PC
contributions, the rest is supposed to be regular and included into the
standard TFFS parameters. An ansatz is proposed to take into account the
so-called tadpole term which ensures the total angular momentum conservation
with g_L^2 accuracy. An approximate method is suggested to take into account
higher order terms in g_L^2. Calculations are carried out for four odd-proton
chains, the odd Tl, Bi, In and Sb ones. Different PC corrections strongly
cancel each other. In the result, the total PC correction to the magnetic
moment in magic nuclei is, as a rule, negligible. In non-magic nuclei
considered it is noticeable and, with only one exception, negative. On average
it is of the order of -(0.1 - 0.5) \mu_N and improves the agreement of the
theory with the data. Simultaneously we calculated the gyromagnetic ratio
g_L^{ph} of all low-lying phonons in 208Pb. For the 3^-_1 state it is rather
close to the Bohr-Mottelson model prediction whereas for other L-phonons, two
5^- and six positive parity states, the difference from the Bohr-Mottelson
values is significant.Comment: 21 pages, 24 figure
Enhanced low-energy -decay strength of Ni and its robustness within the shell model
Neutron-capture reactions on very neutron-rich nuclei are essential for
heavy-element nucleosynthesis through the rapid neutron-capture process, now
shown to take place in neutron-star merger events. For these exotic nuclei,
radiative neutron capture is extremely sensitive to their -emission
probability at very low energies. In this work, we present
measurements of the -decay strength of Ni over the wide range
MeV. A significant enhancement is found in the
-decay strength for transitions with MeV. At present,
this is the most neutron-rich nucleus displaying this feature, proving that
this phenomenon is not restricted to stable nuclei. We have performed
-strength calculations within the quasiparticle time-blocking
approximation, which describe our data above MeV very well.
Moreover, large-scale shell-model calculations indicate an nature of the
low-energy strength. This turns out to be remarkably robust with
respect to the choice of interaction, truncation and model space, and we
predict its presence in the whole isotopic chain, in particular the
neutron-rich .Comment: 9 pages, 9 figure
Quadrupole moments of odd-odd near-magic nuclei
Ground state quadrupole moments of odd-odd near-double-magic nuclei are calculated in the approximation of non-interacting odd neutron and odd proton. Under such a simple approximation the problem is reduced to the calculations of quadrupole moments of corresponding odd-even nuclei. These calculations are performed within the self-consistent Theory of Finite Fermi Systems based on the Energy Density Functional by Fayans et al. with the known DF3-a parameters. A reasonable agreement with the available experimental data is obtained for odd-odd nuclei and odd near-magic nuclei investigated. The self-consistent approach under consideration allowed us to predict the unknown quadrupole moments of odd-even and odd-odd nuclei near the double-magic 56,78Ni, 100,132Sn nuclides