7,158 research outputs found
Long wavelength infrared detector
Long wavelength infrared detection is achieved by a detector made with layers of quantum well material bounded on each side by barrier material to form paired quantum wells, each quantum well having a single energy level. The width and depth of the paired quantum wells, and the spacing therebetween, are selected to split the single energy level with an upper energy level near the top of the energy wells. The spacing is selected for splitting the single energy level into two energy levels with a difference between levels sufficiently small for detection of infrared radiation of a desired wavelength
Passivation of high temperature superconductors
The surface of high temperature superconductors such as YBa2Cu3O(7-x) are passivated by reacting the native Y, Ba and Cu metal ions with an anion such as sulfate or oxalate to form a surface film that is impervious to water and has a solubility in water of no more than 10(exp -3) M. The passivating treatment is preferably conducted by immersing the surface in dilute aqueous acid solution since more soluble species dissolve into the solution. The treatment does not degrade the superconducting properties of the bulk material
Dirac Quasinormal Modes of New Type Black Holes in New Massive Gravity
We study new type black holes in three-dimensional New Massive Gravity and we
calculate analytically the quasinormal modes for fermionic perturbations for
some special cases. Then, we show that for these cases the new type black holes
are stable under fermionic field perturbations.Comment: improved version. arXiv admin note: text overlap with
arXiv:1306.5974, arXiv:1404.317
Motion of particles on a Four-Dimensional Asymptotically AdS Black Hole with Scalar Hair
Motivated by black hole solutions with matter fields outside their horizon,
we study the effect of these matter fields in the motion of massless and
massive particles. We consider as background a four-dimensional asymptotically
AdS black hole with scalar hair. The geodesics are studied numerically and we
discuss about the differences in the motion of particles between the
four-dimensional asymptotically AdS black holes with scalar hair and their
no-hair limit, that is, Schwarzschild AdS black holes. Mainly, we found that
there are bounded orbits like planetary orbits in this background. However, the
periods associated to circular orbits are modified by the presence of the
scalar hair. Besides, we found that some classical tests such as perihelion
precession, deflection of light and gravitational time delay have the standard
value of general relativity plus a correction term coming from the cosmological
constant and the scalar hair. Finally, we found a specific value of the
parameter associated to the scalar hair, in order to explain the discrepancy
between the theory and the observations, for the perihelion precession of
Mercury and light deflection.Comment: 20 pages and 9 figures. arXiv admin note: text overlap with
arXiv:1309.216
Dirac quasinormal modes of two-dimensional charged Dilatonic Black Holes
We study charged fermionic perturbations in the background of two-dimensional
charged Dilatonic black holes, and we present the exact Dirac quasinormal
modes. Also, we study the stability of these black holes under charged
fermionic perturbations.Comment: version accepted for publication in EPJC. arXiv admin note:
substantial text overlap with arXiv:1404.5371, arXiv:1404.602
Compact extra dimensions in cosmologies with f(T) structure
The presence of compact extra dimensions in cosmological scenarios in the
context of f(T)-like gravities is discussed. For the case of toroidal
compactifications, the analysis is performed in an arbitrary number of extra
dimensions. Spherical topologies for the extra dimensions are then carefully
studied in six and seven spacetime dimensions, where the proper vielbein fields
responsible for the parallelization process are found.Comment: 11 pages, one figure (added). Typos corrected, manuscript improved.
Additional material is contained in section IV. Accepted for publication in
Physical Review
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