Results 1 - 10 of 4343
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[en] The neutrino mixing angle θ13 is one of the parameters that relate the neutrino flavor eigenstates to the mass eigenstates. The phenomenon of neutrino oscillations (the periodic change in the probability of measuring a certain neutrino flavor as a function of the distance traveled by the neutrino) proves that the flavor eigenstates are not aligned with the mass eigenstates, and that neutrinos are massive particles. Unlike the other neutrino mixing angles, θ12 and θ23, the angle θ13 is small and was measured for the first time in 2011 and 2012 by several experiments, Double Chooz among them. The value of θ13 is important not only because it is a fundamental parameter of nature but also because only if the three angles are non-null CP violation can occur in neutrino oscillations The Double Chooz experiment measures θ13 from the disappearance of electron antineutrinos (ve) in the antineutrino flux emitted by the reactor cores of the Chooz nuclear power plant (France). The ve are detected using the inverse β-decay reaction (IBD): ve + p → e + + n. Two identical detectors are used: one close to the reactor cores (a∼ 400 m, the Near Detector) which measures the ve flux where the disappearance has barely begun, and another away from the reactor cores (a∼ 1050 m, the Far Detector) which measures the ?e flux where the disappearance is almost maximal. As a consequence of the identicalness between detectors, the uncertainties on the reactor ve flux and the detection of the ve are reduced, increasing the precision of the measurement of θ13. (Author)
[en] The dependences of the sputtering coefficient on the types of accelerated ions, their energy, and the angle of incidence on a target are calculated. For Ar–Si, Хе–С, and H–W systems, acceptable coincidence between the calculated and experimental data is obtained. Two mechanisms for secondary-particle ejection from solids are established; they determine the dependences of the base sputtering coefficient for the base on the energy and the angle of primary ion incidence on the target.
[en] We show that amphoteric refraction of ballistic electrons, i.e., positive or negative refraction depending on the incidence angle, occurs at an interface between an isotropic and an anisotropic medium and can be employed to steer and collimate electron beams. The steering angle is determined by the materials’ parameters, but the degree of collimation can be tuned in a significant range by changing the energy of ballistic electrons.
[en] We propose a numerical model to describe laser ablation of a copper target by a femtosecond laser pulse at an oblique angle of incidence. The model is based on the two temperature model and improved to include laser fluence, laser spot size, and dynamic changes in reflectivity of the target. Numerical results show that the electron and lattice temperatures decrease with the angle of incidence. The dependency of the maximum temperature with angle of incidence follow a cosine power law. The threshold laser fluence, ablation depth and crater size depend on the polarization and angle of the incident laser beam. Our model is supported by the experimental results reported by other group working in femtosecond pulsed laser ablation. (paper)
[en] Initially, the importance of incident angle insensitive property for metamaterial (MTM) absorbers has been discussed in this paper. Later, two different novel approaches to design incident angle insensitive MTM absorbers have been given. Using these two approaches, two incident angle insensitive MTM absorbers have been designed, simulated, fabricated and measured. Additional to incidence angle insensitive property, the two MTM absorbers also exhibits polarization angle insensitive property. Eight-fold and four-fold symmetrical natures of the two MTM absorbers are responsible for the polarization angle insensitive property. Both the absorbers use FR4 substrate having thickness 0.6 mm as a dielectric. One absorber has a resonant frequency of 7.8 GHz and for another one, it is 4.8 GHz. In one absorber, eight smaller radius circles around a basic MTM unit cell provide angle insensitive property. In the second absorber, cross-shaped copper etchings form basic unit cell provide the angle insensitive property. In one case, up to 75° and in another case, up to 70° incident angles, absorptivity of more than 80% has been achieved. (paper)
[en] The influence of the incident angle on the imaging quality of reflective ghost imaging is investigated through atmospheric turbulence. It is shown that under mediate turbulence, small angles have almost no effect on the imaging quality, while the result for direct imaging gets slightly worse. An increase of the incident angle leads to the degradation of the imaging quality of direct imaging and ghost imaging, while the imaging quality of the latter is better under the same angle and turbulent intensity. For large angles, the image from direct imaging cannot be distinguished under mediate turbulence, but ghost imaging can obtain a relatively good ghost image. Moreover, the relationship between the fidelity and the incident angle under different turbulent intensities is presented. (paper)
[en] In the present paper, a 3D model is developed to evaluate the reflectivity of an etched surface with pyramids. This model determines primary and secondary reflections by tracing parallel light beams from the location of each surface element. The model is then applied to predict total reflectivity and area fraction of illumination as a function of the angle of incidence and mean pyramid height. The reduction in the reflectivity of a surface is obtained by increasing the mean pyramid height, or by increasing the angle of incidence, irrespective of the mean pyramid height. However, the reflectivity is asymptotic to a constant value as the angle of incidence is lowered to a sufficiently small value
[en] Starting from the Luneberg lens index profile, we apply the transformation design method to the problem of far-field imaging of (infinitely) distant objects. This analysis yields a single element lens with a planar image surface, zero aberrations of all orders, zero F-number and (in some cases) constant aperture for all angles of incidence.