We explore oscillations of the solar B8 neutrinos in the Earth in detail. The relative excess of night νe events (the day-night asymmetry) is computed as function of the neutrino energy and the nadir ...angle η of its trajectory. The finite energy resolution of the detector causes an important attenuation effect, while the layer-like structure of the Earth density leads to an interesting parametric suppression of the oscillations. Different features of the η− dependence encode information about the structure (such as density jumps) of the Earth density profile; thus measuring the η distribution allows the scanning of the interior of the Earth. We estimate the sensitivity of the DUNE experiment to such measurements. About 75 neutrino events are expected per day in 40 kt. For high values of Δm212 and Eν>11 MeV, the corresponding D-N asymmetry is about 4% and can be measured with 15% accuracy after 5 years of data taking. The difference of the D-N asymmetry between high and low values of Δm212 can be measured at the 4σ level. The relative excess of the νe signal varies with the nadir angle up to 50%. DUNE may establish the existence of the dip in the η− distribution at the (2–3)σ level.
The attenuation effect is the effect of weakening contributions to the oscillation signal from remote structures of the matter density profile. The effect is a consequence of integration over the ...neutrino energy within the energy resolution interval. Structures of a density profile situated at distances larger than the attenuation length, λatt, are not “seen” at the level ε≡2EV/Δm2, where V is the matter potential. We show that the origins of attenuation are (i) the averaging of oscillations in certain layer(s) of matter, (ii) the smallness of the matter effect: ε≪1, and (iii) the specific initial and final states on neutrinos. We elaborate on the graphic description of the attenuation that allows us to compute explicitly the effects in the ε2 order for various density profiles and oscillation channels. The attenuation in the case of partial averaging is described. The effect is crucial for the interpretation of oscillation data and for the oscillation tomography of the Earth with low energy (solar, supernova, atmospheric, etc.) neutrinos.
The paper investigates the interaction of femtosecond laser pulses with the thin films of copper, gold, and platinum. It considers electron-phonon relaxation processes and melting in the metal system ...nonequilibrium heated by laser radiation. Instead of the approximated formula by Wang et al. Phys. Rev. B 50, 8016 (1994), which is widely used to determine the temperature dependence of the electron-phonon coupling factor, we propose an improved approach for its more accurate calculation from first principles. Comparison with experiments and other calculations shows our approach to provide good calculation accuracy. Melting time versus absorbed energy density was estimated for the films and shown to be markedly sensitive to latent heat at low absorbed energy densities (<1 MJ/kg). Our calculations taken to study the temporal evolution of the (220) diffraction peak intensity after femtosecond irradiation show good agreement between experimental and theoretical data, which was attained due to higher accuracy in our determination of the temperature dependence electron-phonon coupling factor.
The paper presents ab initio studies into the relative stability of the crystalline structures of copper, silver, and platinum up to high pressures at T ≥ 0 K. Our calculations in quasiharmonic ...approximation suggest that not the fcc structure of Cu and Ag, but the body-centered cubic one, is thermodynamically most favorable at P ≳ 100 GPa and T > 3 kK. The shock Hugoniot of Cu and Ag crosses the fcc-bcc phase boundary and the calculated transition pressures agree well with the result of recent laser shock experiments by Sharma et al. The advantage of the bcc structure comes from its softer low-frequency phonon modes and the smaller contribution of lattice vibrations to free energy at high temperatures, as compared to close-packed structures. The compression of platinum crystal also causes the fcc → bcc transition but at much higher pressures, P > 1.4 TPa.
The IR absorption spectroscopy in the region of valence vibrations of OH
–
groups, the photoluminescence in the optical spectral range, and the photoinduced light scattering have been used to study ...the peculiarities of the defect structure and their influence on the properties of LiNbO
3
:Zn crystals doped in a wide concentration range including two concentration thresholds (at ~3.0 mol % ZnO and ~6.8 mol % ZnO in melt). In the LiNbO
3
:Zn (0.004–2.01 mol % ZnO) crystals, the concentration of hydroxyl groups increases and the luminescence intensity from the luminescence centers related to Nb
Li
defects decreases as the zinc concentration increases. The latter is likely to be related to the formation of shallow energy levels near the conduction band bottom as niobium atoms are displaced by zinc atoms from the lithium positions of the ideal structure and, correspondingly, the decrease in the Nb
Li
defect concentration. In highly doped L-iNbO
3
:Zn (4.46–6.5 mol % ZnO) crystals and the LiNbO
3stoich
(6.0 wt % K
2
O) crystal, the concentration of OH
–
groups is markedly lower, the energy gap width increases by 0.3–0.4 eV, the luminescence intensity in the green spectral range increases due to the formation of new recombination channels as compared to the weakly doped crystals. In addition, in such crystals, the proton electrical conductivity increases due to the increase in the concentration of interstitial hydrogen H
+
and, as a result, the formation of set of shallow acceptor level near the valence band top.
We report on the thorough investigation of light emitting diodes (LEDs) made of core-shell nanorods (NRs) with InGaN/GaN quantum wells (QWs) in the outer shell, which are grown on patterned ...substrates by metal-organic vapor phase epitaxy. The multi-bands emission of the LEDs covers nearly the whole visible region, including UV, blue, green, and orange ranges. The intensity of each emission is strongly dependent on the current density, however the LEDs demonstrate a rather low color saturation. Based on transmission electron microscopy data and comparing them with electroluminescence and photoluminescence spectra measured at different excitation powers and temperatures, we could identify the spatial origination of each of the emission bands. We show that their wavelengths and intensities are governed by different thicknesses of the QWs grown on different crystal facets of the NRs as well as corresponding polarization-induced electric fields. Also the InGaN incorporation strongly varies along the NRs, increasing at their tips and corners, which provides the red shift of emission. With increasing the current, the different QW regions are activated successively from the NR tips to the side-walls, resulting in different LED colors. Our findings can be used as a guideline to design effectively emitting multi-color NR-LEDs.
Large fine mode–dominated aerosols (submicron radius) in size distributions retrieved from the Aerosol Robotic Network (AERONET) have been observed after fog or low‐altitude cloud dissipation events. ...These column‐integrated size distributions have been obtained at several sites in many regions of the world, typically after evaporation of low‐altitude cloud such as stratocumulus or fog. Retrievals with cloud‐processed aerosol are sometimes bimodal in the accumulation mode with the larger‐size mode often ∼0.4–0.5μm radius (volume distribution); the smaller mode, typically ∼0.12 to ∼0.20 μm, may be interstitial aerosol that were not modified by incorporation in droplets and/or aerosol that are less hygroscopic in nature. Bimodal accumulation mode size distributions have often been observed from in situ measurements of aerosols that have interacted with clouds, and AERONET size distribution retrievals made after dissipation of cloud or fog are in good agreement with particle sizes measured by in situ techniques for cloud‐processed aerosols. Aerosols of this type and large size range (in lower concentrations) may also be formed by cloud processing in partly cloudy conditions and may contribute to the “shoulder” of larger‐size particles in the accumulation mode retrievals, especially in regions where sulfate and other soluble aerosol are a significant component of the total aerosol composition. Observed trends of increasing aerosol optical depth (AOD) as fine mode radius increased suggests higher AOD in the near‐cloud environment and higher overall AOD than typically obtained from remote sensing owing to bias toward sampling at low cloud fraction.
Key Points
Fine mode bimodal size distributions observed after cloud/fog dissipation
Cloud‐processed mode radius in good agreement with in situ measurements
Fine mode large radius shoulder may indicate effects of cloud interaction
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