23,425 research outputs found
Nuclear Dynamics with the Sky3D code
A description is presented of how to use the Sky3D time-dependent
Hartree-Fock code to calculate giant monopole resonances. This requires
modification to the code, and a step-by-step guide of how to make the necessary
modification is given. An example of how to analyse the output of the code to
obtain quantities of physics interest is included. Together, the modifications
and the post-processing are intended to serve as a typical example of how the
code, which was designed to be extendable to particular users' needs, can be
extended.Comment: submitted to Proceedings of the International Workshop on Nuclear
Theory 33 (Rila, Bulgaria
Planetary magnetic fields
As a consequence of the smallness of the electronic fine structure constant, the characteristic time scale for the free diffusive decay of a magnetic field in a planetary core is much less than the age of the Solar System, but the characteristic time scale for thermal diffusion is greater than the age of the Solar System. Consequently, primordial fields and permanent magnetism are small and the only means of providing a substantial planetary magnetic field is the dynamo process. This requires a large region which is fluid, electrically conducting and maintained in a non-uniform motion that includes a substantial RMS vertical component. The attributes of fluidity and conductivity are readily provided in the deep interiors of all planets and most satellites, either in the form of an Fe alloy with a low eutectic temperature (e.g. Fe-S-O in terrestrial bodies and satellites) or by the occupation of conduction states in fluid hydrogen or 'ice' (H2O-NH3-CH4) in giant planets. It is argued that planetary dynamos are almost certainly maintained by convection (compositional and/or thermal)
Higgs fields, bundle gerbes and string structures
We use bundle gerbes and their connections and curvings to obtain an explicit
formula for a de Rham representative of the string class of a loop group
bundle. This is related to earlier work on calorons.Comment: 15 page
On the Stable Relative Orientation of Groups Connected by a Carbon-Carbon Single Bond
Langseth and his co-workers [1] have recently applied the results of essentially incomplete spectroscopic studies of liquid cyclohexane, symmetrical tetrachloroethane, and ethylene deuterobromide to a discussion of the intramolecular forces restricting internal rotation about the C-C bond. We believe that none of their structural conclusions is correct. Their discussion is based on their conclusion that in these molecules the opposed or eclipse configurations are the stable ones. Insofar as liquid cyclohexane and symmetrical tetrachloroethane are concerned this conclusion is most probably incorrect since it directly contradicts the results of a great number of more straightforward studies of these and similar molecules
Continuum time-dependent Hartree-Fock for giant resonances in spherical nuclei
This paper deals with the solution of the spherically symmetric
time-dependent Hartree-Fock approximation applied in the case of nuclear giant
monopole resonances. The problem is spatially unbounded as the resonance state
is in the continuum. The practical requirement to perform the calculation in a
finite-sized spatial region results in a difficulty with the spatial boundary
conditions. Here we propose a absorbing boundary condition scheme to handle the
conflict. The derivation, via a Laplace transform method, and implementation is
described. The accuracy and efficiency of the scheme is tested and the results
presented to support the case that they are a effective way of handling the
artificial boundary.Comment: 13 pages, 8 figure
Low-Energy Heavy-Ion Reactions and the Skyrme Effective Interaction
The Skyrme effective interaction, with its multitude of parameterisations,
along with its implemen- tation using the static and time-dependent density
functional (TDHF) formalism have allowed for a range of microscopic
calculations of low-energy heavy-ion collisions. These calculations allow
variation of the effective interaction along with an interpretation of the
results of this variation informed by a comparison to experimental data.
Initial progress in implementing TDHF for heavy-ion collisions necessarily used
many approximations in the geometry or the interaction. Over the last decade or
so, the implementations have overcome all restrictions, and studies have begun
to be made where details of the effective interaction are being probed. This
review surveys these studies in low energy heavy-ion reactions, finding
significant effects on observables from the form of the spin-orbit interaction,
the use of the tensor force, and the inclusion of time-odd terms in the density
functional.Comment: submitted to Prog. Part. Nucl. Phy
- …