181,838 research outputs found
Anisotropy of Resonant Inelastic X-Ray Scattering at the K Edge of Si:Theoretical Analysis
We investigate theoretically the resonant inelastic x-ray scattering (RIXS)
at the edge of Si on the basis of an ab initio calculation. We calculate
the RIXS spectra with systematically varying transfered-momenta,
incident-photon energy and incident-photon polarization. We confirm the
anisotropy of the experimental spectra by Y. Ma {\it et al}. (Phys. Rev. Lett.
74, 478 (1995)), providing a quantitative explanation of the spectra.Comment: 18 pages, 11 figure
Nearly Mass-Degenerate Majorana Neutrinos: Double Beta Decay and Neutrino Oscillations
Assuming equal tree-level Majorana masses for the standard-model neutrinos,
either from the canonical seesaw mechanism or from a heavy scalar triplet, I
discuss how their radiative splitting may be relevant to neutrinoless double
beta decay and neutrino oscillations.Comment: 12 pages, including 4 figures, talk at NANP9
Notch effects in tensile behavior of AM60 magnesium alloys
The deformation and failure behavior of an AM60 magnesium alloy was investigated using tensile test on circumferentially notched specimens with different notch radii. The strain and stress triaxiality corresponding to the failure point were evaluated using both analytical and finite element analyses. Combining with systematical observations of the fracture surfaces, it is concluded that deformation and failure of AM60 magnesium alloy are notch (constraint) sensitive. The failure mechanisms change from ductile tearing to quasi cleavage with the increase of constraint
Exotic behavior and crystal structures of calcium under pressure
Experimental studies established that calcium undergoes several
counterintuitive transitions under pressure: fcc \rightarrow bcc \rightarrow
simple cubic \rightarrow Ca-IV \rightarrow Ca-V, and becomes a good
superconductor in the simple cubic and higher-pressure phases. Here, using ab
initio evolutionary simulations, we explore the behavior of Ca under pressure
and find a number of new phases. Our structural sequence differs from the
traditional picture for Ca, but is similar to that for Sr. The {\beta}-tin
(I41/amd) structure, rather than simple cubic, is predicted to be the
theoretical ground state at 0 K and 33-71 GPa. This structure can be
represented as a large distortion of the simple cubic structure, just as the
higher-pressure phases stable between 71 and 134 GPa. The structure of Ca-V,
stable above 134 GPa, is a complex host-guest structure. According to our
calculations, the predicted phases are superconductors with Tc increasing under
pressure and reaching ~20 K at 120 GPa, in good agreement with experiment
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