111 research outputs found
The Role of Ground State Correlations in the Single-Particle Strength of Odd Nuclei with Pairing
A method based on the consistent use of the Green function formalism has been
developed to calculate the distribution of the single-particle strength in odd
nuclei with pairing. The method takes into account the quasiparticle-phonon
interaction, ground state correlations and a "refinement" of phenomenological
single-particle energies and pairing gap values from the quasiparticle-phonon
interaction under consideration. The calculations for 121Sn and 119Sn that were
performed in the quasiparticlephonon approximation, have shown a
reasonable agreement with experiment. The ground state correlations play a
noticeable role and mostly improve the agreement with experiment or shift the
results to the right direction.Comment: 11 page
Effects of the triaxial deformation and pairing correlation on the proton emitter 145Tm
The ground-state properties of the recent reported proton emitter 145Tm have
been studied within the axially or triaxially deformed relativistic mean field
(RMF) approaches, in which the pairing correlation is taken into account by the
BCS-method with a constant pairing gap. It is found that triaxiality and
pairing correlations play important roles in reproducing the experimental one
proton separation energy. The single-particle level, the proton emission orbit,
the deformation parameters beta = 0.22 and gamma = 28.98 and the corresponding
spectroscopic factor for 145Tm in the triaxial RMF calculation are given as
well.Comment: 17 pages, 7 figures and 1 table. accepted by Physical Review
Possible doublet mechanism for a regular component of parity violation in neutron scattering
A nucleus with octupole deformation of the mean field reveals rotational
doublets with the same angular momentum and opposite parity. Mediated by the
Coriolis-type interaction, the doublet structure leads to a strong regular
component in the parity violation caused by weak interaction. This can explain
sign correlations observed in polarized neutron scattering by Th.Comment: 10 pages, revtex, no figure
Role of dynamical particle-vibration coupling in reconciliation of the puzzle for spherical proton emitters
It has been observed that decay rate for proton emission from
single particle state is systematically quenched compared with the prediction
of a one dimensional potential model although the same model successfully
accounts for measured decay rates from and states. We
reconcile this discrepancy by solving coupled-channels equations, taking into
account couplings between the proton motion and vibrational excitations of a
daughter nucleus. We apply the formalism to proton emitting nuclei
Re to show that there is a certain range of parameter set of the
excitation energy and the dynamical deformation parameter for the quadrupole
phonon excitation which reproduces simultaneously the experimental decay rates
from the 2, 3 and 1 states in these nuclei.Comment: RevTex, 12 pages, 4 eps figure
Quantum time scales in alpha tunneling
The theoretical treatment of alpha decay by Gamow is revisited by
investigating the quantum time scales in tunneling. The time spent by an alpha
particle in front of the barrier and traversing it before escape is evaluated
using microscopic alpha nucleus potentials. The half-life of a nucleus is shown
to correspond to the time spent by the alpha knocking in front of the barrier.
Calculations for medium and super heavy nuclei show that from a multitude of
available tunneling time definitions, the transmission dwell time gives the
bulk of the lifetime of the decaying state, in most cases.Comment: LaTex, 1 figure, new comments and references adde
Decay Rate of Triaxially-Deformed Proton Emitters
The decay rate of a triaxially-deformed proton emitter is calculated in a
particle-rotor model, which is based on a deformed Woods-Saxon potential and
includes a deformed spin-orbit interaction. The wave function of the
ground state of the deformed proton emitter Ho is obtained
in the adiabatic limit, and a Green's function technique is used to calculate
the decay rate and branching ratio to the first excited 2 state of the
daughter nucleus. Only for values of the triaxial angle
is good agreement obtained for both the total decay rate and the 2
branching ratio.Comment: 19 pages, 4 figure
Two-proton radioactivity and three-body decay. III. Integral formulae for decay widths in a simplified semianalytical approach
Three-body decays of resonant states are studied using integral formulae for
decay widths. Theoretical approach with a simplified Hamiltonian allows
semianalytical treatment of the problem. The model is applied to decays of the
first excited state of Ne and the ground state of
Fe. The convergence of three-body hyperspherical model calculations to
the exact result for widths and energy distributions are studied. The
theoretical results for Ne and Fe decays are updated and
uncertainties of the derived values are discussed in detail. Correlations for
the decay of Ne state are also studied.Comment: 19 pages, 20 figure
Solution of the microscopic gap equation for a slab of nuclear matter with the Paris NN-potential
The gap equation in the -channel is solved for a nuclear slab with the
separable form of the Paris potential. The gap equation is considered in the
model space in terms of the effective pairing interaction which is found in the
complementary subspace. The absolute value of the gap turned out to be
very sensitive to the cutoff in the momentum space in the equation
for the effective interaction. It is necessary to take to guarantee 1% accuracy for . The gap equation itself is
solved directly, without any additional approximations. The solution reveals
the surface enhancement of the gap which was earlier found with an
approximate consideration. A strong surface-volume interplay was found also
implying a kind of the proximity effect. The diagonal matrix elements of
turned out to be rather close to the empirical values for heavy atomic
nuclei.Comment: 17 pages, 12 figure
Parity violation in reaction: resonance approach
The method based on microscopic theory of nuclear reactions has been applied
for the analysis of parity violating effects in a few-body systems. Different
parity violating and parity conserving asymmetries and their dependence on
neutron energy have been estimated for reaction.
The estimated effects are in a good agreement with available exact
calculations
Effects of T- and P-odd weak nucleon interaction in nuclei: renormalizations due to residual strong interaction, matrix elements between compound states and their correlations with P-violating matrix elements
Manifestations of P-,T-odd weak interaction between nucleons in nucleus are
considered. Renormalization of this interaction due to residual strong
interaction is studied. Mean squared matrix elements of P-,T-odd weak
interaction between compound states are calculated. Correlators between
P-,T-odd and P-odd, T-even weak interaction matrix elements between compound
states are considered and estimates for these quantities are obtained.Comment: Submitted to Phys. Rev. C; 21 pages, REVTEX 3, no figure
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