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Results for “Elastic scattering”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Spatially and Temporally-Resolved Multi-Parameter Interferometric Rayleigh Scattering

A novel approach to simultaneously measure the translational temperature, bulk velocity, and density in gases by collecting, referencing, and analyzing nanosecond time-scale Rayleigh scattered light from molecules is described. A narrow-band pulsed laser source is used to probe two largely separated measurement locations, one of which is used for reference. The elastically scattered photons containing information from both measurement locations are collected at the same time and analyzed spectrally using a planar Fabry - Perot interferometer. A practical means of referencing the measurement of velocity using the laser frequency, and the density and temperature using the information from the reference measurement location maintained at constant properties is described. To demonstrate the technique single-shot spectra of elastic scattered light are obtained in a near zero velocity H2-air Hencken burner flame and simultaneously in an N2-filled gas cell. A simplified Gaussian distribution model to the scattered light spectra is used to obtain the flame properties. Corrections to this model are applied at lower gas temperatures when the simplified Gaussian approximation is no longer suitable. The near-zero measured velocity as a function of the measured flame temperature, and a comparison of the measured flame density and temperature with the perfect gas law are presented.

Bivolaru, Daniel↗
DOE OSTI2025

Controlled Shifts of X-ray Emission Lines Measured with Transition Edge Sensors at the Advanced Photon Source

The measurement of shifts in the energy of X-ray emission lines is important for understanding the electronic structure and physical properties of materials. In this study, we demonstrate a method using a synchrotron source to introduce controlled eV-scale shifts of a narrow line in between fixed-energy fluorescence lines. We use this to characterize the ability of a hard X-ray superconducting Transition Edge Sensor (TES) array to measure line shifts. Fixed fluorescence lines excited by higher harmonics of the monochromatic X-ray beam are used for online energy calibration, while elastic scattering from the primary harmonic acts as the variable energy emission line under study. We use this method to demonstrate the ability to track shifts in the energy of the elastic scattering line of magnitude smaller than the TES energy resolution, and find we are ultimately limited by our calibration procedure. The method can be applied over a wide X-ray energy range and provides a robust approach for the characterization of the ability of high-resolution detectors to detect X-ray emission line shifts, and the quantitative comparison of energy calibration procedures.

Guruswamy, Tejas (ORCID:0000000241656765)↗
NASA NTRS1997

Electron Excitation Cross Sections for the S II Transitions: 3s(exp 2)3p(exp 3) 4S(exp o) approaches 3s(exp 2)3p(exp 3) 2D(exp o), 2P(exp o), and 3s3p(exp 4) 4P

Experimental and theoretical collisional excitation cross sections are reported for the transitions 3s(exp 2)3p(exp 3)4S(exp o) approaches 3s(exp 2)3p(exp 3) 2D(exp o), 2P(exp o), and 3s3P(exp 4) 4P in S II. The transition wavelengths (energies) are 6716 A (1.85 eV), 4069 A (3.05 eV), and 1256 A (9.87 eV), respectively. In the experiments, use is made of the energy-loss merged-beams method. The metastable fraction of the S II beam was assessed and minimized. The contribution of elastically scattered electrons was reduced by the use of a lowered solenoidal magnetic field and a modulated radio-frequency voltage on the analyzing plates and by retarding grids to reject the elastically scattered electrons with larger Larmor radii. For each transition, comparisons are made among experiments, the new 19 state R-matrix calculation, and three other close-coupling calculations.

Liao, C.↗
NASA NTRS1987

Energy transfer of O(D-1) atoms in collision with O(P-3) atoms

Calculations are carried out of the elastic scattering and excitation exchange cross-sections in collisions of O(D-1) and O(P-3) atoms, which determine the degree of thermalization of the O(D-1) atoms produced by dissociative recombination in the thermosphere. The effective elastic scattering and excitation exchange cross-sections are calculated to be 1.55 x 10 to the -15th and 6.25 x 10 to the -16th sq cm, respectively, at a relative collision energy of 1.0 eV. The mutual diffusion coefficient between O(D-1) and O(P-3) atoms is also presented.

Yee, Jeng-Hwa↗
NASA NTRS1980

Absolute elastic differential electron scattering cross sections for He - A proposed calibration standard from 5 to 200 eV

Absolute differential, integral, and momentum-transfer cross sections for electrons elastically scattered from helium are reported for the impact energy range of 5 to 200 eV. Angular distributions for elastically scattered electrons are measured in a crossed-beam geometry using a collimated, differentially pumped atomic-beam source which requires no effective-path-length correction. Below the first inelastic threshold the angular distributions were placed on an absolute scale by use of a phase-shift analysis. Above this threshold, the angular distributions from 10 to 140 deg were fitted using the phase-shift technique, and the resulting integral cross sections were normalized to a semiempirically derived integral elastic cross section. Depending on the impact energy, the data are estimated to be accurate to within 5 to 9%.

Register, D. F.↗
NASA NTRS1988

Cross Sections, relic abundance, and detection rates for neutralino dark matter

Neutralino annihilation and elastic scattering cross sections are derived which differ in important ways from previous work. These are applied to relic abundance calculations and to direct detection of neutralino dark matter from the galactic halo. Assuming the neutralino to be the lightest supersymmetric particle and that it is less massive than the Z sup 0, we find relic densities of neutralinos greater than 4 percent of critical density for almost all values of the supersymmetric parameters. We constrain the parameter space by using results from PETRA (chargino mass less than 23 GeV) and ASP, and then assuming a critical density of neutralinos, display event rates in a cryogenic detector for a variety of models. A new term implies spin independent elastic scattering even for those majorana particles and inclusion of propagator momenta increases detection rates by 10 to 300 percent for pure photinos. Z sup 0-squark interference leads to very low detection rates for some values of the parameters. The new term in the elastic cross section dominates for heavy, mostly spinless materials and mitigates the negative interference cancellations in light materials; except for the pure photino or pure higgsinos cases where it does not contribute. In general, the rates can be substantially different from the pure photino and pure higgsino special cases usually considered.

Griest, Kim↗
NASA NTRS1976

Electron detachment from negative ions - The effects of isotopic substitution

Absolute total electron-detachment cross sections and relative elastic-scattering cross sections are presented for collisions of H(-) or D(-) with He, Ne, Ar, and N2 for collision energies ranging from about 2 eV up to 100 eV. Special emphasis has been given to the effect of isotopic substitution. It was found that, with the exception of the helium target, the results cannot be in accord with a model using a localized complex potential. On the other hand, the results for H(-) or D(-) with He are in excellent agreement with predictions based on previous (local complex potential) analysis of differential elastic-scattering measurements.

Champion, R. L.↗
DOE OSTI2025

Supernova pointing capabilities of DUNE

The determination of the direction of a stellar core collapse via its neutrino emission is crucial for the identification of the progenitor for a multimessenger follow-up. A highly effective method of reconstructing supernova directions within the Deep Underground Neutrino Experiment (DUNE) is introduced. The supernova neutrino pointing resolution is studied by simulating and reconstructing electron-neutrino charged-current absorption on 40 Ar and elastic scattering of neutrinos on electrons. Procedures to reconstruct individual interactions, including a newly developed technique called “brems flipping,” as well as the burst direction from an ensemble of interactions are described. Performance of the burst direction reconstruction is evaluated for supernovae happening at a distance of 10 kpc for a specific supernova burst flux model. The pointing resolution is found to be 3.4 degrees at 68% coverage for a perfect interaction-channel classification and a fiducial mass of 40 kton, and 6.6 degrees for a 10 kton fiducial mass respectively. Assuming a 4% rate of charged-current interactions being misidentified as elastic scattering, DUNE’s burst pointing resolution is found to be 4.3 degrees (8.7 degrees) at 68% coverage.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Supernova pointing capabilities of DUNE

The determination of the direction of a stellar core collapse via its neutrino emission is crucial for the identification of the progenitor for a multimessenger follow-up. A highly effective method of reconstructing supernova directions within the Deep Underground Neutrino Experiment (DUNE) is introduced. The supernova neutrino pointing resolution is studied by simulating and reconstructing electron-neutrino charged-current absorption on Ar 40 and elastic scattering of neutrinos on electrons. Procedures to reconstruct individual interactions, including a newly developed technique called “brems flipping,” as well as the burst direction from an ensemble of interactions are described. Performance of the burst direction reconstruction is evaluated for supernovae happening at a distance of 10 kpc for a specific supernova burst flux model. The pointing resolution is found to be 3.4 degrees at 68% coverage for a perfect interaction-channel classification and a fiducial mass of 40 kton, and 6.6 degrees for a 10 kton fiducial mass respectively. Assuming a 4% rate of charged-current interactions being misidentified as elastic scattering, DUNE’s burst pointing resolution is found to be 4.3 degrees (8.7 degrees) at 68% coverage.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2026

Neutrino-induced charged-current coherent pion production for constraining the muon neutrino flux at DUNE

We study neutrino-induced charged-current coherent pion production ( ν μ CC - Coh π ) as a tool for constraining the neutrino flux at the Deep Underground Neutrino Experiment (DUNE). The neutrino energy and flavor in the process can be directly reconstructed from the outgoing particles, making it especially useful to specifically constrain the muon neutrino component of the total flux. The cross section of this process can be obtained using the Adler relation with the π -Ar elastic scattering cross section taken either from external data or, as we explore, from a simultaneous measurement in the DUNE near detector. We develop a procedure that leverages ν μ CC - Coh π events to fit for the neutrino flux while simultaneously accounting for relevant effects in the cross section. We project that this method has the statistical power to constrain the uncertainty on the normalization of the flux at its peak to a few percent. This study demonstrates the potential utility of a ν μ CC - Coh π flux constraint, though further work will be needed to determine the range of validity and precision of the Adler relation upon which it relies, as well as to measure the π -Ar elastic scattering cross section to the requisite precision. We discuss the experimental and phenomenological developments necessary to unlock the ν μ CC - Coh π process as a “standard candle” for neutrino experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Neutrino Induced Charged Current Coherent Pion Production for Constraining the Muon Neutrino Flux at DUNE

We study neutrino induced charge current coherent pion production (νμ CC-Coh π) as a tool for constraining the neutrino flux at the Deep Underground Neutrino Experiment (DUNE). The neutrino energy and flavor in the process can be directly reconstructed from the outgoing particles, making it especially useful to specifically constrain the muon neutrino component of the total flux. The cross section of this process can be obtained using the Adler relation with the π-Ar elastic scattering cross section, taken either from external data or, as we explore, from a simultaneous measurement in the DUNE near detector. We develop a procedure that leverages νμ CC-Coh π events to fit for the neutrino flux while simultaneously accounting for relevant effects in the cross section. We project that this method has the statistical power to constrain the uncertainty on the normalization of the flux at its peak to a few percent. This study demonstrates the potential utility of aνμ CC-Coh π flux constraint, though further work will be needed to determine the range of validity and precision of the Adler relation upon which it relies, as well as to measure the π-Ar elastic scattering cross section to the requisite precision. We discuss the experimental and phenomenological developments necessary to unlock the νμ CC-Coh π process as a "standard candle'' for neutrino experiments.

Putnam, Gray [Fermilab]↗
NASA NTRS1975

Pure rotational excitation of H2 at electron impact energies of 3 to 100 eV

Cross sections for pure rotational excitation in H2 are obtained using two different crossed-beam type electron-impact spectrometers with three sets of conditions: at electron energies of 15-100 eV and scattering angles of 115 deg; 3-40 eV at 20 deg; 40 eV at 10-135 deg. For intermediate-energy electrons the pure rotational excitation cross section at large scattering angles exceeds the elastic scattering cross section at electron energies greater than about 30 eV. Rotational cross sections are found to decrease slowly with decreasing electron energy, with a magnitude at their peak (at 4 eV) about 20 times that at 100 eV. It is suggested that these results may account in part for the large population of excited rotational states observed in interstellar H2.

Srivastava, S. K.↗