6,434 research outputs found
Nuclear density-functional theory and fission of super-heavy elements
We review the prediction of fission properties of super-heavy elements (SHE)
by self-consistent mean-field models thereby concentrating on the widely used
Skyrme-Hartree-Fock (SHF) approach. We explain briefly the theoretical tools:
the SHF model, the calibration of model parameters together with statistical
analysis of uncertainties and correlations, and the involved computation of
fission lifetimes. We present an overview of fission stability in comparison to
other decay channels over the whole landscape of SHE reaching deep into the
-process domain. The main emphasis lies on a detailed discussion of the
various ingredients determining eventually the fission properties. The main
result is that fission is an involved process which explores many different
influences with almost equal share, basic bulk properties (also known as
liquid-drop model parameters), pairing strengths, and shell effects. %Comment: 9 figures, 1 tabl
The search for continuous gravitational waves: metric of the multi-detector F-statistic
We develop a general formalism for the parameter-space metric of the
multi-detector F-statistic, which is a matched-filtering detection statistic
for continuous gravitational waves. We find that there exists a whole family of
F-statistic metrics, parametrized by the (unknown) amplitude parameters of the
gravitational wave. The multi-detector metric is shown to be expressible in
terms of noise-weighted averages of single-detector contributions, which
implies that the number of templates required to cover the parameter space does
not scale with the number of detectors. Contrary to using a longer observation
time, combining detectors of similar sensitivity is therefore the
computationally cheapest way to improve the sensitivity of coherent
wide-parameter searches for continuous gravitational waves.
We explicitly compute the F-statistic metric family for signals from isolated
spinning neutron stars, and we numerically evaluate the quality of different
metric approximations in a Monte-Carlo study. The metric predictions are tested
against the measured mismatches and we identify regimes in which the local
metric is no longer a good description of the parameter-space structure.Comment: 20 pages, 15 figures, revtex4; v2: some edits of style and notation,
fixed minor typo
Misfits in Skyrme-Hartree-Fock
We address very briefly five critical points in the context of the
Skyrme-Hartree-Fock (SHF) scheme: 1) the impossibility to consider it as an
interaction, 2) a possible inconsistency of correlation corrections as, e.g.,
the center-of-mass correction, 3) problems to describe the giant dipole
resonance (GDR) simultaneously in light and heavy nuclei, 4) deficiencies in
the extrapolation of binding energies to super-heavy elements (SHE), and 5) a
yet inappropriate trend in fission life-times when going to the heaviest SHE.
While the first two points have more a formal bias, the other three points have
practical implications and wait for solution.Comment: 9 pages, 4 figure
Contact angles on heterogeneous surfaces; a new look at Cassie's and Wenzel's laws
We consider a three dimensional liquid drop sitting on a rough and chemically
heterogeneous substrate. Using a novel minimization technique on the free
energy of this system, a generalized Young's equation for the contact angle is
found. In certain limits, the Cassie and Wenzel laws, and a new equivalent
rule, applicable in general, are derived. We also propose an equation in the
same spirit as these results but valid on a more `microscopic' level.
Throughout we work under the presence of gravity and keep account of line
tension terms.Comment: 10 pages RevTeX, 2 EPS figures. A few minor corrections mad
The two-proton shell gap in Sn isotopes
We present an analysis of two-proton shell gaps in Sn isotopes. As the
theoretical tool we use self-consistent mean-field models, namely the
relativistic mean-field model and the Skyrme-Hartree-Fock approach, both with
two different pairing forces, a delta interaction (DI) model and a
density-dependent delta interaction (DDDI). We investigate the influence of
nuclear deformation as well as collective correlations and find that both
effects contribute significantly. Moreover, we find a further significant
dependence on the pairing force used. The inclusion of deformation plus
correlation effects and the use of DDDI pairing provides agreement with the
data.Comment: gzipped tar archiv containing LaTeX source, bibliography file
(*.bbl), all figures as *.eps, and the style file
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