71 research outputs found
The T=0 neutron-proton pairing correlations in the superdeformed rotational bands around 60Zn
The superdeformed bands in 58Cu, 59Cu, 60Zn, and 61Zn are analyzed within the
frameworks of the Skyrme-Hartree-Fock as well as Strutinsky-Woods-Saxon total
routhian surface methods with and without the T=1 pairing correlations. It is
shown that a consistent description within these standard approaches cannot be
achieved. A T=0 neutron-proton pairing configuration mixing of
signature-separated bands in 60Zn is suggested as a possible solution to the
problem.Comment: 9 ReVTex pages, 10 figures, submitted to Phys. Rev.
Isovector and isoscalar superfluid phases in rotating nuclei
The subtle interplay between the two nuclear superfluids, isovector T=1 and
isoscalar T=0 phases, are investigated in an exactly soluble model. It is shown
that T=1 and T=0 pair-modes decouple in the exact calculations with the T=1
pair-energy being independent of the T=0 pair-strength and vice-versa. In the
rotating-field, the isoscalar correlations remain constant in contrast to the
well known quenching of isovector pairing. An increase of the isoscalar (J=1,
T=0) pair-field results in a delay of the bandcrossing frequency. This
behaviour is shown to be present only near the N=Z line and its experimental
confirmation would imply a strong signature for isoscalar pairing collectivity.
The solutions of the exact model are also discussed in the
Hartree-Fock-Bogoliubov approximation.Comment: 5 pages, 4 figures, submitted to PR
Angular momentum projection of cranked Hartree-Fock states: Application to terminating bands in A~44 nuclei
We present the first systematic calculations based on the angular-momentum
projection of cranked Slater determinants. We propose the Iy --> I scheme, by
which one projects the angular momentum I from the 1D cranked state constrained
to the average spin projection of =I. Calculations performed for the
rotational band in 46Ti show that the AMP Iy --> I scheme offers a natural
mechanism for correcting the cranking moment of inertia at low-spins and
shifting the terminating state up by ~2 MeV, in accordance with data. We also
apply this scheme to high-spin states near the band termination in A~44 nuclei,
and compare results thereof with experimental data, shell-model calculations,
and results of the approximate analytical symmetry-restoration method proposed
previously.Comment: 9 RevTeX pages, 8 EPS figures, submitted to Physical Review
Microscopic calculations of isospin mixing in N~Z nuclei and isospin-symmetry-breaking corrections to the superallowed beta-decay
Recently, we have applied for the first time the angular momentum and isospin
projected nuclear density functional theory to calculate the isospin-symmetry
breaking (ISB) corrections to the superallowed beta-decay. With the calculated
set of the ISB corrections we found |V_{ud}|=0.97447(23) for the leading
element of the Cabibbo-Kobayashi-Maskawa matrix. This is in nice agreement with
both the recent result of Towner and Hardy [Phys. Rev. {\bf C77}, 025501
(2008)] and the central value deduced from the neutron decay. In this work we
extend our calculations of the ISB corrections covering all superallowed
transitions A,I^\pi=0^+,T=1,T_z \rightarrow A,I^\pi=0^+,T=1,T_z+1 with T_z
=-1,0 and A ranging from 10 to 74.Comment: Invited talk presented by WS at the Nordic Conference on Nuclear
Physics, June 13-17, 2011, Stockholm, Sweden; Accepted for publication in
Physica Scripta, Figure 1 has been correcte
Hyperfine interactions of 57Fe in Pt3Fe in Pt 3Fe - Ab initio and Mossbauer effect studies
The Mossbauer effect and ab initio investigations of an electric ¯eld gradient at 57Fe nuclei in Pt3Fe compound
are presented. It is shown that nonzero 57Fe electric ¯eld gradient exists in the cubic Pt3Fe. Ab initio study
of Pt3Fe in antiferromagnetic state con¯rms the presence of electric ¯eld gradient at 57Fe nuclei. Lattice, local
valence electron (3d, 4p) and weakly bound 3p core electron contributions to electric ¯eld gradient are separated
out and discussed in the context of the electronic structure changes upon the antiferromagnetic phase transition
Cranked Relativistic Hartree-Bogoliubov Theory: Superdeformed Bands in the Region
Cranked Relativistic Hartree-Bogoliubov (CRHB) theory is presented as an
extension of Relativistic Mean Field theory with pairing correlations to the
rotating frame. Pairing correlations are taken into account by a finite range
two-body force of Gogny type and approximate particle number projection is
performed by Lipkin-Nogami method. This theory is applied to the description of
yrast superdeformed rotational bands observed in even-even nuclei of the mass region. Using the well established parameter sets NL1 for the
Lagrangian and D1S for the pairing force one obtains a very successful
description of data such as kinematic () and dynamic ()
moments of inertia without any adjustment of new parameters. Within the present
experimental accuracy the calculated transition quadrupole moments agree
reasonably well with the observed data.Comment: 6 pages including 4 PostScript figures, uses RevTex, revised version,
Phys.Rev. C, Rapid Communications, in pres
Pronounced Shape Change Induced by Quasiparticle Alignment
Mean lifetimes of high-spin states of 74Kr have been determined using the Doppler-shift attenuation method. The high-spin states were studied using the 40Ca(40Ca,α2p) reaction at a beam energy of 160 MeV with the GASP γ-ray spectrometer. The ground-state band and negative parity side band show the presence of three different configurations in terms of transitional quadrupole deformations. A dramatic shape change was found along the ground-state band after the S-band crossing. The deduced quadrupole deformation changes are well reproduced by cranked Woods-Saxon Strutinsky calculations
Local Density Approximation for proton-neutron pairing correlations. I. Formalism
In the present study we generalize the self-consistent
Hartree-Fock-Bogoliubov (HFB) theory formulated in the coordinate space to the
case which incorporates an arbitrary mixing between protons and neutrons in the
particle-hole (p-h) and particle-particle (p-p or pairing) channels. We define
the HFB density matrices, discuss their spin-isospin structure, and construct
the most general energy density functional that is quadratic in local
densities. The consequences of the local gauge invariance are discussed and the
particular case of the Skyrme energy density functional is studied. By varying
the total energy with respect to the density matrices the self-consistent
one-body HFB Hamiltonian is obtained and the structure of the resulting mean
fields is shown. The consequences of the time-reversal symmetry, charge
invariance, and proton-neutron symmetry are summarized. The complete list of
expressions required to calculate total energy is presented.Comment: 22 RevTeX page
Time-odd mean fields in the rotating frame: microscopic nature of nuclear magnetism
The microscopic role of nuclear magnetism in rotating frame is investigated
for the first time in the framework of the cranked relativistic mean field
theory. It is shown that nuclear magnetism modifies the expectation values of
single-particle spin, orbital and total angular momenta along the rotational
axis effectively creating additional angular momentum. This effect leads to the
increase of kinematic and dynamic moments of inertia at given rotational
frequency and has an impact on effective alignments.Comment: 16 pages, 4 figures, submitted to Physical Review
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