52 research outputs found
Influence of Co spin-state on optical properties of LaCoO and HoCoO
Optical properties of the isoelectronic compounds LaCoO and HoCoO has
been experimentally and theoretically investigated. We've measured the real
and imaginary parts of the dielectric
function, reflectance and optical conductivity at room temperature.
The shift of the most pronounced spectral features to the high energy region on
0.3 eV associated with larger distortions due to the smaller rare earth ionic
radii in HoCoO in comparison with LaCoO was observed. Also there was
found an enhancement of absorption intensity in the range 1.3-2.3 eV in all
kinds of spectra in HoCoO, which can be attributed basing on the results of
LDA+U calculations to the different spin-states of Co ion in these
compounds. The shift of the onset of the absorption from less than 0.1 eV in
LaCoO to 0.7 eV in HoCoO and an absorption intensity enhancement in a
narrow spectral range 1.2-2.6 eV in HoCoO are clearly seen from the
calculated convolution of partial densities of states obtained in the LDA+U
approach. Such changes are assumed to be induced by the different Co
spin-state in these compounds at room temperature.Comment: 10 pages, 3 figure
Electronic properties of WTe2 and MoTe2 single crystals
WTe2 and MoTe2 single crystals were grown, and their electrical resistivity in the temperature range from 80 K to 300 K, optical properties at room temperature in the spectral range of 0.17-5.0 eV were studied as well as theoretical calculations of the electronic structure were performed. It is shown that the temperature dependence of the electrical resistivity of orthorhombic WTe2 has a metallic type with resistivity value of (0.5-1) mOhmcm, while hexagonal MoTe2 has a semiconductor one and resistivity value (0.5-1) Ohmcm, which is three orders of magnitude larger than the resistivity of WTe2. Optical properties indicated that there is no contribution from free carriers in the entire spectral range studied. The calculated densities of the electronic states of MoTe2 and WTe2 showed the presence of a bunch of the molybdenum and tungsten electronic states in a wide energy interval with strong admixing of tellurium states. In the WTe2 compound, the larger number of the electronic states is located near the Fermi energy, characterizing a more metallic state in this compound as compared to MoTe2. © Published under licence by IOP Publishing Ltd.Government Council on Grants, Russian Federation: 02, 211Russian Foundation for Basic Research, RFBR: 17-52-52008Ministry of Education and Science of the Russian Federation, Minobrnauka: АААА-А18-118020190098-5The research was carried out within the state assignment of Ministry of Education and Science of the Russian Federation (theme “Spin” No. АААА-А18-118020290104-2 and theme “Electron” No. АААА-А18-118020190098-5), supported in part by RFBR (Project No. 17-52-52008) and the Government of Russian Federation (Decree No. 211, Contract No. 02.A03.21.0006)
ОПРЕДЕЛЕНИЕ АЭРОДИНАМИЧЕСКИХ ХАРАКТЕРИСТИК ОДИНОЧНОЙ ЛОПАСТИ НЕСУЩЕГО ВИНТА В ПАКЕТАХ FLOEFD, ANSYS FLUENT И RC-VTOL
The results of computational simulation of helicopter rotor's single blade flow, for which experimental (model test) data are published, are represented in this article. The calculations were made in the universal software package of CFD modeling FloEFD, which was based on the solution of averaged equations' system of Navier-Stocks, as well as in the program software RC-VTOL using the vortex method. The obtained results are compared with experimental data and modeling results in the program software ANSYS Fluent (license of TsAGI Nr. 501024). The work shows satisfactory, and in some cases good calculation data reconciliation getting with different techniques including experimental.В работе представлены результаты численного моделирования обтекания одиночной лопасти несущего винта. Расчеты проводились в универсальном пакете CFD (Calculation Fluid Dynamic) моделирования FloEFD, основанном на решении системы осредненных уравнений Навье-Стокса, а также в программном комплексе RC-VTOL, использующем вихревые методы. Полученные результаты сравниваются с экспериментальными данными и результатами моделирования в программном пакете ANSYS Fluent (лицензия ЦАГИ №501024). Показано удовлетворительное, а в некоторых случаях и хорошее согласование расчетных данных, полученных по разным методикам, с экспериментальными
Production of {\pi}+ and K+ mesons in argon-nucleus interactions at 3.2 AGeV
First physics results of the BM@N experiment at the Nuclotron/NICA complex
are presented on {\pi}+ and K+ meson production in interactions of an argon
beam with fixed targets of C, Al, Cu, Sn and Pb at 3.2 AGeV. Transverse
momentum distributions, rapidity spectra and multiplicities of {\pi}+ and K+
mesons are measured. The results are compared with predictions of theoretical
models and with other measurements at lower energies.Comment: 29 pages, 20 figure
The HITRAN2020 Molecular Spectroscopic Database
The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years).
All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH3F, GeH4, CS2, CH3I and NF3. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules.
The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITRAN Application Programming Interface (HAPI). The functionality of both tools has been extended for the new edition
Measurements of , , , , and production in 120 GeV/ p + C interactions
This paper presents multiplicity measurements of charged hadrons produced in
120 GeV/ proton-carbon interactions. The measurements were made using data
collected at the NA61/SHINE experiment during two different data-taking
periods, with increased phase space coverage in the second configuration due to
the addition of new subdetectors. Particle identification via was
employed to obtain double-differential production multiplicities of ,
, , , and . These measurements are presented as a
function of laboratory momentum in intervals of laboratory polar angle covering
the range from 0 to 450 mrad. They provide crucial inputs for current and
future long-baseline neutrino experiments, where they are used to estimate the
initial neutrino flux
Measurements of , , and spectra in Ar+Sc collisions at 13 to 150 GeV/
The NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the
onset of deconfinement in strongly interacting matter through a beam energy
scan of particle production in collisions of nuclei of varied sizes. This paper
presents results on inclusive double-differential spectra, transverse momentum
and rapidity distributions and mean multiplicities of , ,
and produced in Ar+Sc collisions at beam momenta of
13, 19, 30, 40, 75 and 150 GeV/. The analysis uses the 10%
most central collisions, where the observed forward energy defines centrality.
The energy dependence of the / ratios as well as of inverse
slope parameters of the transverse mass distributions are placed in
between those found in inelastic + and central Pb+Pb collisions. The
results obtained here establish a system-size dependence of hadron production
properties that so far cannot be explained either within statistical (SMES,
HRG) or dynamical (EPOS, UrQMD, PHSD, SMASH) models
meson production in inelastic p+p interactions at 31, 40 and 80 GeV/c beam momentum measured by NA61/SHINE at the CERN SPS
Measurements of meson production via its decay mode
in inelastic interactions at incident projectile momenta of 31,
40 and 80 GeV/ ( and GeV, respectively) are
presented. The data were recorded by the NA61/SHINE spectrometer at the CERN
Super Proton Synchrotron. Double-differential distributions were obtained in
transverse momentum and rapidity. The mean multiplicities of mesons
were determined to be at
31 GeV/, at 40
GeV/ and at 80
GeV/. The results on production are compared with model
calculations (Epos1.99, SMASH 2.0 and PHSD) as well as with published data from
other experiments.Comment: arXiv admin note: substantial text overlap with arXiv:2106.0753
Search for the critical point of strongly-interacting matter in Ar + Sc collisions at 150A Ge V /c using scaled factorial moments of protons
The critical point of dense, strongly interacting matter is searched for at the CERN SPS in Ar + Sc collisions at 150A Ge V /c. The dependence of second-order scaled factorial moments of proton multiplicity distribution on the number of subdivisions of transverse momentum space is measured. The intermittency analysis is performed using both transverse momentum and cumulative transverse momentum. For the first time, statistically independent data sets are used for each subdivision number. The obtained results do not indicate any statistically significant intermittency pattern. An upper limit on the fraction of correlated proton pairs and the power of the correlation function is obtained based on a comparison with the Power-law Model developed for this purpose
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