19,364 research outputs found
Pairing interactions and the vanishing pairing correlations in hot nuclei
Finite temperature Hartree-Fock-Bogoliubov calculations are performed in Sn
isotopes using Skyrme and zero-range, density-dependent pairing interactions.
For both stable and very neutron-rich nuclei the critical temperature at which
pairing correlations vanish is independent of the volume/surface nature of the
pairing interaction. The value of the critical temperature follows
approximatively the empirical rule T 0.5 for all
the calculated isotopes, showing that the critical temperature could be deduced
from the pairing gap at zero temperature. On the other hand, the pairing gap at
temperatures just below T is strongly sensitive to the volume/surface
nature of the pairing interaction.Comment: 6 pages, 7 figures revised versio
Convergence of Particle-Hole Expansions for the Description of Nuclear Correlations
The convergence properties of a multiparticle-multihole (mp-mh) configuration
mixing approach whose purpose is to describe ground state correlations in
nuclei without particle number and Pauli violations is investigated in the case
of an exactly solvable pairing hamiltonian. Two different truncation schemes
are tested by looking at quantities as correlation energies and single-particle
occupation probabilities. Results show that pairing correlations present in
usual superfluid nuclei can be accurately described using up to 6 particle-6
hole excitations, a convergence fast enought for envisaging extensions to fully
microscopic calculations.Comment: 8 pages, 4 figure
Superfluid Properties of the Inner Crust of Neutron Stars
Superfluid properties of the inner crust matter of neutron stars, formed by
nuclear clusters immersed in a dilute neutron gas, are analysed in a self-
consistent HFB approach. The calculations are performed with two pairing
forces, fixed so as to obtain in infinite nuclear matter the pairing gaps
provided by the Gogny force or by induced interactions. It is shown that the
nuclear clusters can either suppress or enhance the pairing correlations inside
the inner crust matter, depending on the density of the surrounding neutrons.
The profile of the pairing field in the inner crust is rather similar for both
pairing forces, but the values of the pairing gaps are drastically reduced for
the force which simulates the polarisation effects in infinite neutron matter.Comment: 13 pages, 6 figures. Corrected typos and new format. To appear in
Phys. Rev.
Influence of complex configurations on properties of pygmy dipole resonance in neutron-rich Ca isotopes
Starting from the quasiparticle random phase approximation based on the
Skyrme interaction SLy5, we study the effects of phonon-phonon coupling~(PPC)
on the low-energy electric dipole response in Ca. Using the same set
of parameters we describe available experimental data for Ca and
give prediction for Ca. The inclusion of the PPC results in the
formation of low-energy states. There is an impact of the PPC effect on
low-energy ~strength of Ca. The PPC effect on the electric
dipole polarizability is discussed. We predict a strong increase of the summed
~strength below 10MeV, with increasing neutron number from Ca till
Ca.Comment: 11 pages, 10 figure
Structure of low-lying quadrupole states in nuclei near 132Sn
The properties of the low-lying 2^+ states in the even-even nuclei around
132Sn are studied within the quasiparticle random phase approximation. Starting
from a Skyrme interaction in the particle-hole channel and a density-dependent
zero-range interaction in the particle-particle channel, we use the finite rank
separable approach in our investigation. It is found that the fourth 2^+ state
in 132Te could be a good candidate for a mixed-symmetry state.Comment: 6 pages, 2 figures, proceedings of International Conference on
Nuclear Structure and Related Topics (NSRT09), June 2009, JINR, Dubna, Russi
Sensitivity of -decay rates to the radial dependence of the nucleon effective mass
We analyze the sensitivity of -decay rates in 78 Ni and 100,132 Sn to
a correction term in Skyrme energy-density functionals (EDF) which modifies the
radial shape of the nucleon effective mass. This correction is added on top of
several Skyrme parametrizations which are selected from their effective mass
properties and predictions about the stability properties of 132 Sn. The impact
of the correction on high-energy collective modes is shown to be moderate. From
the comparison of the effects induced by the surface-peaked effective mass in
the three doubly magic nuclei, it is found that 132 Sn is largely impacted by
the correction, while 78 Ni and 100 Sn are only moderately affected. We
conclude that -decay rates in these nuclei can be used as a test of
different parts of the nuclear EDF: 78 Ni and 100 Sn are mostly sensitive to
the particle-hole interaction through the B(GT) values, while 132 Sn is
sensitive to the radial shape of the effective mass. Possible improvements of
these different parts could therefore be better constrained in the future
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