19,062 research outputs found
Barrier modification in sub-barrier fusion reactions using Wong formula with Skyrme forces in semiclassical formalism
We obtain the nuclear proximity potential by using semiclassical extended
Thomas Fermi (ETF) approach in Skyrme energy density formalism (SEDF), and use
it in the extended -summed Wong formula under frozen density
approximation. This method has the advantage of allowing the use of different
Skyrme forces, giving different barriers. Thus, for a given reaction, we could
choose a Skyrme force with proper barrier characteristics, not-requiring extra
``barrier lowering" or ``barrier narrowing" for a best fit to data. For the
Ni+Mo reaction, the -summed Wong formula, with effects of
deformations and orientations of nuclei included, fits the fusion-evaporation
cross section data exactly for the force GSkI, requiring additional barrier
modifications for forces SIII and SV. However, the same for other similar
reactions, like Ni+Ni, fits the data best for SIII force.
Hence, the barrier modification effects in -summed Wong expression
depends on the choice of Skyrme force in extended ETF method.Comment: INPC2010, Vancouver, CANAD
Shell closure effects studied via cluster decay in heavy nuclei
The effects of shell closure in nuclei via the cluster decay is studied. In
this context, we have made use of the Preformed Cluster Model () of Gupta
and collaborators based on the Quantum Mechanical Fragmentation Theory. The key
point in the cluster radioactivity is that it involves the interplay of close
shell effects of parent and daughter. Small half life for a parent indicates
shell stabilized daughter and long half life indicates the stability of the
parent against the decay. In the cluster decay of trans lead nuclei observed so
far, the end product is doubly magic lead or its neighbors. With this in our
mind we have extended the idea of cluster radioactivity. We investigated decay
of different nuclei where Zirconium is always taken as a daughter nucleus,
which is very well known deformed nucleus. The branching ratio of cluster decay
and -decay is also studied for various nuclei, leading to magic or
almost doubly magic daughter nuclei. The calculated cluster decay half-life are
in well agreement with the observed data. First time a possibility of cluster
decay in nucleus is predicted
Nilpotent (anti-)BRST symmetry transformations for dynamical non-Abelian 2-form gauge theory: superfield formalism
We derive the off-shell nilpotent and absolutely anticommuting
Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations for the
dynamical non-Abelian 2-form gauge theory within the framework of geometrical
superfield formalism. We obtain the (anti-) BRST invariant coupled Lagrangian
densities that respect the above nilpotent symmetry transformations. We
discuss, furthermore, this (anti-) BRST invariance in the language of the
superfield formalism. One of the novel features of our investigation is the
observation that, in addition to the horizontality condition, we have to invoke
some other physically relevant restrictions to deduce the exact (anti-) BRST
symmetry transformations for all the fields of the topologically massive
non-Abelian gauge theory.Comment: LaTeX file, 8 pages, typos fixed in some equations, journal-versio
Crystal structure of [1-(3-chlorophenyl)- 5-hydroxy-3-methyl-1H-pyrazol-4-yl](p-tolyl) methanone
RK acknowledges the Department of Science & Technology for the single-crystal X-ray diffractometer sanctioned as a National Facility under Project No. SR/S2/CMP-47/2003.Peer reviewe
Emission of intermediate mass fragments from hot Ba formed in low-energy Ni+Ni reaction
The complex fragments (or intermediate mass fragments) observed in the
low-energy Ni+NiBa reaction, are studied within
the dynamical cluster decay model for s-wave with the use of the
temperature-dependent liquid drop, Coulomb and proximity energies. The
important result is that, due to the temperature effects in liquid drop energy,
the explicit preference for -like fragments is washed out, though the
C (or the complementary Sn) decay is still predicted to be one
of the most probable -nucleus decay for this reaction. The production
rates for non- like intermediate mass fragments (IMFs) are now higher
and the light particle production is shown to accompany the IMFs at all
incident energies, without involving any statistical evaporation process in the
model. The comparisons between the experimental data and the (s-wave)
calculations for IMFs production cross sections are rather satisfactory and the
contributions from other -waves need to be added for a further
improvement of these comparisons and for calculations of the total kinetic
energies of fragments.Comment: 22 pages, 15 figure
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