3,769 research outputs found
Development of space-syaple thermal-control coatings triannual report, jan. 20 - may 20, 1965
Development of stable thermal control coatings with low solar absorptance to infrared emittance rati
Model-independent Limits from Spin-dependent WIMP Dark Matter Experiments
Spin-dependent WIMP searches have traditionally presented results within an
odd group approximation and by suppressing one of the spin-dependent
interaction cross sections. We here elaborate on a model-independent analysis
in which spin-dependent interactions with both protons and neutrons are
simultaneously considered. Within this approach, equivalent current limits on
the WIMP-nucleon interaction at WIMP mass of 50 GeV/c are either
pb, pb or ,
depending on the choice of cross section or coupling strength
representation. These limits become less restrictive for either larger or
smaller masses; they are less restrictive than those from the traditional odd
group approximation regardless of WIMP mass. Combination of experimental
results are seen to produce significantly more restrictive limits than those
obtained from any single experiment. Experiments traditionally considered
spin-independent are moreover found to severely limit the spin-dependent phase
space. The extension of this analysis to the case of positive signal
experiments is explored.Comment: 12 pages, 12 figures, submitted to Phys. Rev.
Solution of two-center time-dependent Dirac equation in spherical coordinates: Application of the multipole expansion of the electron-nuclei interaction
A non-perturbative approach to the solution of the time-dependent, two-center
Dirac equation is presented with a special emphasis on the proper treatment of
the potential of the nuclei. In order to account for the full multipole
expansion of this potential, we express eigenfunctions of the two-center
Hamiltonian in terms of well-known solutions of the "monopole" problem that
employs solely the spherically-symmetric part of the interaction. When combined
with the coupled-channel method, such a wavefunction-expansion technique allows
for an accurate description of the electron dynamics in the field of moving
ions for a wide range of internuclear distances. To illustrate the
applicability of the proposed approach, the probabilities of the K- as well as
L- shell ionization of hydrogen-like ions in the course of nuclear alpha-decay
and slow ion-ion collisions have been calculated
Evidence against correlations between nuclear decay rates and Earth-Sun distance
We have reexamined our previously published data to search for evidence of
correlations between the rates for the alpha, beta-minus, beta-plus, and
electron-capture decays of 22Na, 44Ti, 108Agm, 121Snm, 133Ba, and 241Am and the
Earth-Sun distance. We find no evidence for such correlations and set limits on
the possible amplitudes of such correlations substantially smaller than those
observed in previous experiments
Dynamical symmetry of isobaric analog 0+ states in medium mass nuclei
An algebraic sp(4) shell model is introduced to achieve a deeper
understanding and interpretation of the properties of pairing-governed 0+
states in medium mass atomic nuclei. The theory, which embodies the simplicity
of a dynamical symmetry approach to nuclear structure, is shown to reproduce
the excitation spectra and fine structure effects driven by proton-neutron
interactions and isovector pairing correlations across a broad range of nuclei.Comment: 7 pages, 5 figure
- …