The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
R Volkamer - One of the best experts on this subject based on the ideXlab platform.
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rayleigh Scattering Cross Section measurements of nitrogen argon oxygen and air
Journal of Quantitative Spectroscopy & Radiative Transfer, 2014Co-Authors: Ryan Thalman, Kyle J Zarzana, Margaret A Tolbert, R VolkamerAbstract:Abstract Knowledge about Rayleigh Scattering Cross Sections is relevant to predictions about radiative transfer in the atmosphere, and needed to calibrate the reflectivity of mirrors that are used in high-finesse optical cavities to measure atmospheric trace gases and aerosols. In this work we have measured the absolute Rayleigh Scattering Cross-Section of nitrogen at 405.8 and 532.2 nm using cavity ring-down spectroscopy (CRDS). Further, multi-spectral measurements of the Scattering Cross-Sections of argon, oxygen and air are presented relative to that of nitrogen from 350 to 660 nm using Broadband Cavity Enhanced Spectroscopy (BBCES). The reported measurements agree with refractive index based theory within 0.2±0.4%, and have an absolute accuracy of better than 1.3%. Our measurements expand the spectral range over which Rayleigh Scattering Cross Section measurements of argon, oxygen and air are available at near-ultraviolet wavelengths. The expressions used to represent the Rayleigh Scattering Cross-Section in the literature are evaluated to assess how uncertainties affect quantities measured by cavity enhanced absorption spectroscopic (CEAS) techniques. We conclude that Rayleigh Scattering Cross Sections calculated from theory provide accurate data within very low error bounds, and are suited well to calibrate CEAS measurements of atmospheric trace gases and aerosols.
E Barrelet - One of the best experts on this subject based on the ideXlab platform.
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measurement of the inclusive e p Scattering Cross Section at high inelasticity y and of the structure function f l
European Physical Journal C, 2011Co-Authors: F D Aaron, C Alexa, V Andreev, S Backovic, A Baghdasaryan, E Barrelet, W Bartel, S Baghdasaryan, O Behrend, P BelovAbstract:A measurement is presented of the inclusive neutral current e\pm p Scattering Cross Section using data collected by the H1 experiment at HERA during the years 2003 to 2007 with proton beam energies Ep of 920, 575, and 460 GeV. The kinematic range of the measurement covers low absolute four-momentum transfers squared, 1.5 GeV2 < Q2 < 120 GeV2, small values of Bjorken x, 2.9 \cdot 10-5 < x < 0.01, and extends to high inelasticity up to y = 0.85. The structure function FL is measured by combining the new results with previously published H1 data at Ep = 920 GeV and Ep = 820 GeV. The new measurements are used to test several phenomenological and QCD models applicable in this low Q2 and low x kinematic domain.
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a precision measurement of the inclusive ep Scattering Cross Section at hera
European Physical Journal C, 2009Co-Authors: F D Aaron, C Alexa, K Alimujiang, V Andreev, B Antunovic, A Asmone, S Backovic, A Baghdasaryan, E Barrelet, W BartelAbstract:A measurement of the inclusive deep inelastic neutral current e(+) p Scattering Cross Section is reported in the region of four-momentum transfer squared, 12GeV(2) <= Q(2) <= 150 GeV2, and Bjorken x, 2 x 10(-4) <= x <= 0.1. The results are based on data collected by the H1 Collaboration at the ep collider HERA at positron and proton beam energies of E-e = 27.6 GeV and E-p = 920 GeV, respectively. The data are combined with previously published data, taken at E-p = 820 GeV. The accuracy of the combined measurement is typically in the range of 1.3-2%. A QCD analysis at next-to-leading order is performed to determine the parton distributions in the proton based on H1 data.
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measurement of the inclusive ep Scattering Cross Section at low q 2 and x at hera
European Physical Journal C, 2009Co-Authors: F D Aaron, C Alexa, V Andreev, B Antunovic, A Asmone, S Backovic, A Baghdasaryan, S Aplin, A Astvatsatourov, E BarreletAbstract:A measurement of the inclusive ep Scattering Cross Section is presented in the region of low momentum transfers, 0.2 GeV2 a parts per thousand currency signQ (2)a parts per thousand currency sign12 GeV2, and low Bjorken x, 5a <...10(-6)a parts per thousand currency signxa parts per thousand currency sign0.02. The result is based on two data sets collected in dedicated runs by the H1 Collaboration at HERA at beam energies of 27.6 GeV and 920 GeV for positrons and protons, respectively. A combination with data previously published by H1 leads to a Cross Section measurement of a few percent accuracy. A kinematic reconstruction method exploiting radiative ep events extends the measurement to lower Q (2) and larger x. The data are compared with theoretical models which apply to the transition region from photoproduction to deep inelastic Scattering.
M Brown - One of the best experts on this subject based on the ideXlab platform.
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measurement of the elastic Scattering Cross Section of neutrons from argon and neon
Physical Review C, 2013Co-Authors: S Macmullin, M F Kidd, R Henning, W Tornow, C R Howell, M BrownAbstract:Background: The most significant source of background in direct dark matter searches are neutrons that scatter elastically from nuclei in the detector's sensitive volume. Experimental data for the elastic Scattering Cross Section of neutrons from argon and neon, which are target materials of interest to the dark matter community, were previously unavailable. Purpose: Measure the differential Cross Section for elastic Scattering of neutrons from argon and neon in the energy range relevant to backgrounds from (alpha,n) reactions in direct dark matter searches. Method: Cross-Section data were taken at the Triangle Universities Nuclear Laboratory (TUNL) using the neutron time-of-flight technique. These data were fit using the spherical optical model. Results: The differential Cross Section for elastic scatting of neutrons from neon at 5.0 and 8.0 MeV and argon at 6.0 MeV was measured. Optical-model parameters for the elastic Scattering reactions were determined from the best fit to these data. The total elastic Scattering Cross Section for neon was found to differ by 6% at 5.0 MeV and 13% at 8.0 MeV from global optical-model predictions. Compared to a local optical-model for 40Ar, the elastic Scattering Cross Section was found to differ from the data by 8% at 6.0 MeV. Conclusions: These new data are important for improving Monte-Carlo simulations and background estimates for direct dark matter searches and for benchmarking optical models of neutron elastic Scattering from these nuclei.
F D Aaron - One of the best experts on this subject based on the ideXlab platform.
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measurement of the inclusive e p Scattering Cross Section at high inelasticity y and of the structure function f l
European Physical Journal C, 2011Co-Authors: F D Aaron, C Alexa, V Andreev, S Backovic, A Baghdasaryan, E Barrelet, W Bartel, S Baghdasaryan, O Behrend, P BelovAbstract:A measurement is presented of the inclusive neutral current e\pm p Scattering Cross Section using data collected by the H1 experiment at HERA during the years 2003 to 2007 with proton beam energies Ep of 920, 575, and 460 GeV. The kinematic range of the measurement covers low absolute four-momentum transfers squared, 1.5 GeV2 < Q2 < 120 GeV2, small values of Bjorken x, 2.9 \cdot 10-5 < x < 0.01, and extends to high inelasticity up to y = 0.85. The structure function FL is measured by combining the new results with previously published H1 data at Ep = 920 GeV and Ep = 820 GeV. The new measurements are used to test several phenomenological and QCD models applicable in this low Q2 and low x kinematic domain.
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a precision measurement of the inclusive ep Scattering Cross Section at hera
European Physical Journal C, 2009Co-Authors: F D Aaron, C Alexa, K Alimujiang, V Andreev, B Antunovic, A Asmone, S Backovic, A Baghdasaryan, E Barrelet, W BartelAbstract:A measurement of the inclusive deep inelastic neutral current e(+) p Scattering Cross Section is reported in the region of four-momentum transfer squared, 12GeV(2) <= Q(2) <= 150 GeV2, and Bjorken x, 2 x 10(-4) <= x <= 0.1. The results are based on data collected by the H1 Collaboration at the ep collider HERA at positron and proton beam energies of E-e = 27.6 GeV and E-p = 920 GeV, respectively. The data are combined with previously published data, taken at E-p = 820 GeV. The accuracy of the combined measurement is typically in the range of 1.3-2%. A QCD analysis at next-to-leading order is performed to determine the parton distributions in the proton based on H1 data.
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measurement of the inclusive ep Scattering Cross Section at low q 2 and x at hera
European Physical Journal C, 2009Co-Authors: F D Aaron, C Alexa, V Andreev, B Antunovic, A Asmone, S Backovic, A Baghdasaryan, S Aplin, A Astvatsatourov, E BarreletAbstract:A measurement of the inclusive ep Scattering Cross Section is presented in the region of low momentum transfers, 0.2 GeV2 a parts per thousand currency signQ (2)a parts per thousand currency sign12 GeV2, and low Bjorken x, 5a <...10(-6)a parts per thousand currency signxa parts per thousand currency sign0.02. The result is based on two data sets collected in dedicated runs by the H1 Collaboration at HERA at beam energies of 27.6 GeV and 920 GeV for positrons and protons, respectively. A combination with data previously published by H1 leads to a Cross Section measurement of a few percent accuracy. A kinematic reconstruction method exploiting radiative ep events extends the measurement to lower Q (2) and larger x. The data are compared with theoretical models which apply to the transition region from photoproduction to deep inelastic Scattering.
V A Volodin - One of the best experts on this subject based on the ideXlab platform.
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on raman Scattering Cross Section ratio of crystalline and microcrystalline to amorphous silicon
Applied Physics Letters, 2018Co-Authors: D M Zhigunov, G N Kamaev, P K Kashkarov, V A VolodinAbstract:In this letter, we report on accurate comparative measurements of Raman Scattering from bulk crystalline Si and from hydrogenated amorphous Si thin films before and after their pulse laser annealing, performed for the purpose of Si crystalline grain formation. Being accompanied by the respective optical transmittance/reflectance measurements, these data allowed us to estimate the integrated Raman Scattering Cross Section ratios of crystalline and microcrystalline Si to hydrogenated amorphous Si and to compare the results with those known from the literature. For crystalline Si, the obtained ratio is equal to 0.75, while for microcrystalline Si, it is equal to at least 2. Our results are found to contradict the proposed earlier exponential decay dependence of the integrated Raman Scattering Cross Section ratio of microcrystalline to amorphous Si on the crystalline grain size. The physical reasons, which support our findings, are discussed.In this letter, we report on accurate comparative measurements of Raman Scattering from bulk crystalline Si and from hydrogenated amorphous Si thin films before and after their pulse laser annealing, performed for the purpose of Si crystalline grain formation. Being accompanied by the respective optical transmittance/reflectance measurements, these data allowed us to estimate the integrated Raman Scattering Cross Section ratios of crystalline and microcrystalline Si to hydrogenated amorphous Si and to compare the results with those known from the literature. For crystalline Si, the obtained ratio is equal to 0.75, while for microcrystalline Si, it is equal to at least 2. Our results are found to contradict the proposed earlier exponential decay dependence of the integrated Raman Scattering Cross Section ratio of microcrystalline to amorphous Si on the crystalline grain size. The physical reasons, which support our findings, are discussed.
