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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Fragmentation of Fe nuclei on carbon, hydrogen and CH2 targets. I - Individual charge changing and total cross sections. II - Isotopic cross sections

The fragmentation of Fe nuclei in carbon and CH2 targets at energies of 650, 800, and 950 MeV/nuc has been studied. Direct measurements of the interaction between Fe nuclei and the carbon and CH2 targets were carried out. The Fe to H charge changing cross sections derived for selected nuclei showed a clear energy dependence, consistent with the results of Westfall et al. (1979). Values for the total inelastic cross section Fe to H charge changing were obtained by two methods: the first method involved subtracting the total CH2 and C cross sections (values of 703 plus or minus 9 mb and 65 plus or minus 10 mb at 950 MeV/nuc and 650 MeV/nuc, respectively were obtained). The same cross sections were obtained by adding the individual charge changing cross sections. A cross section for Fe to fragment into lower mass Fe isotopes of 65 plus or minus 5 mb was also observed, giving total inelastic mass changing cross sections of 768 plus or minus 11 mb and 716 plus or minus 12 mb, respectively. In addition, the individual isotopic cross sections for Z equals 16-25 are reported.

Brautigam, D. A.↗
DOE OSTI2023

Cross-Section Comparison for Pu-238 Production in the Advanced Test Reactor at Idaho National Laboratory

Qualification of Advanced Test Reactor (ATR) positions for Pu-238 production has been ongoing at Idaho National Laboratory (INL). The ATR qualifications have stretched over multiple years during which new techniques have been developed and made available for ATR experiment neutronic analysis. As part of the transition to newer codes, new cross-section libraries have been evaluated for use in the Pu-238 production experiment analysis. A comparative study was done using the MCNP ORGIEN Activation Analysis (MOAA) tool between ENDF/B-VII.0 and ENDF/B-VIII.0 cross sections to capture the impact of the change in cross-sections on the analysis needed to qualify Pu-238 production targets. All comparisons were done assuming the ATR GEN-I targets were located in the south flux trap of the ATR. Finally, an overview of how this qualification and potential irradiation fits into Pu-238 is discussed.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2020

Scattering of electron from a disk in 2D electron gas: Full cross section, transport cross section, and the interaction correction

It is known that the presence of the Fermi sea modifies the scattering of an electron from a point-like impurity. This is due to the Friedel oscillations of the electron density around the impurity. These oscillations create an additional scattering potential for incident electrons. The closer the energy of the incident electron to the Fermi level, the stronger the additional scattering. Here, we study this effect for the case when the impurity is not point-like but rather a hard disk, with a radius much bigger than the de Broglie wavelength. We start with a careful examination of the full and transport cross sections from an extended target. Both cross sections approach their limiting values upon increasing the wave vector of the incident electron. We establish that the transport cross section saturates much faster than the full cross section. With regard to the interaction correction, we establish that it vanishes for the full cross section, while for the transport cross section, it is enhanced compared to the case of a point-like scatterer.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Differential cross section measurements for γ n → π - p above the first nucleon resonance region

The quasifree gamma d -> pi(-)p(p) differential cross section has been measured with CLAS at photon beam energies E-gamma from 0.445 to 2.510 GeV (corresponding to W from 1.311 to 2.366 GeV) for pion center-of-mass angles cos theta(c.m.)(pi) from -0.72 to 0.92. A correction for final state interactions has been applied to these data to extract the gamma n -> pi(-)p differential cross sections. These cross sections are quoted in 8428 (E-gamma, cos theta(c.m)(pi)) bins, a factor of nearly 3 increase in the world statistics for this channel in this kinematic range. These new data help to constrain coupled-channel analysis fits used to disentangle the spectrum of N* resonances and extract their properties. Selected photon decay amplitudes N* -> gamma n at the resonance poles are determined for the first time and are reported here.

CLAS Collaboration↗
DOE OSTI2017

Measurement of the prompt J /$\psi$ pair production cross-section in pp collisions at $\sqrt{s} = 8$ TeV with the ATLAS detector

The production of two prompt J/ψ mesons, each with transverse momenta p T > 8.5 GeV and rapidity |y| < 2.1, is studied using a sample of proton-proton collisions at $\sqrt{s} = 8$ TeV, corresponding to an integrated luminosity of 11.4 fb –1 collected in 2012 with the ATLAS detector at the LHC. The differential cross-section, assuming unpolarised J/ψ production, is measured as a function of the transverse momentum of the lower-p T J/ψ meson, di-J/ψp T and mass, the difference in rapidity between the two J/ψ mesons, and the azimuthal angle between the two J/ψ mesons. The fraction of prompt pair events due to double parton scattering is determined by studying kinematic correlations between the two J/ψ mesons. The total and double parton scattering cross-sections are compared with predictions. The effective cross-section of double parton scattering is measured to be σ eff = 6.3 ± 1.6(stat)±1.0(syst) mb.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1993

Scattered light and accuracy of the cross-section measurements of weak absorptions: Gas and liquid phase UV absorption cross sections of CH3CFCl2

Ultraviolet absorption cross sections of CH3CFCl2(HCFC-141b) were determined in the gas phase (190-260 nm) and liquid phase (230-260 mm) at 298 K. The liquid phase absorption cross sections were then converted into accurate gas phase values using a previously described procedure. It has been demonstrated that scattered light from the shorter-wavelength region (as little as several parts per thousand) can seriously compromise the absorption cross-section measurement, particularly at longer wavelengths where cross sections are low, and can be a source of discrepancies in the cross sections of weakly absorbing halocarbons reported in the literature. A modeling procedure was developed to assess the effect of scattered light on the measured absorption cross section in our experiments, thereby permitting appropriate corrections to be made on the experimental values. Modeled and experimental results were found to be in good agreement. Experimental results from this study were compared with other available determinations and provide accurate input for calculating the atmospheric lifetime of HCFC-141b.

Fahr, A.↗
DOE OSTI2017

Measurement and QCD analysis of double-differential inclusive jet cross sections in pp collisions at $ \sqrt{s}=8 $ TeV and cross section ratios to 2.76 and 7 TeV

A measurement of the double-differential inclusive jet cross section as a function of the jet transverse momentum p$_{T}$ and the absolute jet rapidity |y| is presented. Data from LHC proton-proton collisions at $ \sqrt{s}=8 $ TeV, corresponding to an integrated luminosity of 19.7 fb$^{−1}$, have been collected with the CMS detector. Jets are reconstructed using the anti-k$_{T}$ clustering algorithm with a size parameter of 0.7 in a phase space region covering jet p$_{T}$ from 74 GeV up to 2.5 TeV and jet absolute rapidity up to |y| = 3.0. The low-p$_{T}$ jet range between 21 and 74 GeV is also studied up to |y| = 4.7, using a dedicated data sample corresponding to an integrated luminosity of 5.6 pb$^{−1}$. The measured jet cross section is corrected for detector effects and compared with the predictions from perturbative QCD at next-to-leading order (NLO) using various sets of parton distribution functions (PDF). Cross section ratios to the corresponding measurements performed at 2.76 and 7 TeV are presented. From the measured double-differential jet cross section, the value of the strong coupling constant evaluated at the Z mass is α$_{S}$(M$_{Z}$) = 0.1164$_{− 0.0043}^{+ 0.0060}$ , where the errors include the PDF, scale, nonperturbative effects and experimental uncertainties, using the CT10 NLO PDFs. Improved constraints on PDFs based on the inclusive jet cross section measurement are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of the total cross section from elastic scattering in pp collisions at s = 8 TeV with the ATLAS detector

A measurement of the total ppcross section at the LHC at √s=8TeV is presented. An integrated luminosity of 500 μb-1 was accumulated in a special run with high-β beam optics to measure the differential elastic cross section as a function of the Mandelstam momentum transfer variable t. The measurement is performed with the ALFA sub-detector of ATLAS. Using a fit to the differential elastic cross section in the -t range from 0.014GeV2 to 0.1GeV2 to extrapolate t→0, the total cross section, σtot(pp →X), is measured via the optical theorem to be σtot(pp→ X) = 96.07±0.18 (stat.)±0.85 (exp.)± 0.31 (extr.) mb, where the first error is statistical, the second accounts for all experimental systematic uncertainties and the last is related to uncertainties in the extrapolation t→0. In addition, the slope of the exponential function describing the elastic cross section at small t is determined to be B =19.74 ±0.05 (stat.) ±0.23 (syst.) GeV-2.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of the differential cross-section of highly boosted top quarks as a function of their transverse momentum in s = 8 TeV proton-proton collisions using the ATLAS detector

The differential cross-section for pair production of top quarks with high transverse momentum is measured in 20.3 fb -1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The measurement is performed for t$\bar{t}$t events in the lepton + jets channel. The cross-section is reported as a function of the hadronically decaying top quark transverse momentum for values above 300 GeV. The hadronically decaying top quark is reconstructed as an anti- k t jet with radius parameter R = 1.0 and identified with jet substructure techniques. The observed yield is corrected for detector effects to obtain a cross-section at particle level in a fiducial region close to the event selection. A parton-level cross-section extrapolated to the full phase space is also reported for top quarks with transverse momentum above 300 GeV. The predictions of a majority of next-to-leading-order and leading-order matrix-element Monte Carlo generators are found to agree with the measured cross-sections.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of the Inelastic Proton-Proton Cross Section at s = 13 TeV with the ATLAS Detector at the LHC

This Letter presents a measurement of the inelastic proton-proton cross section using 60 μ b -1 of p p collisions at a center-of-mass energy √ s of 13 TeV with the ATLAS detector at the LHC. Inelastic interactions are selected using rings of plastic scintillators in the forward region ( 2.07 < | η | < 3.86 ) of the detector. A cross section of 68.1 ± 1.4 mb is measured in the fiducial region ξ = M $2\atop{X}$ / s > 10 - 6 , where M X is the larger invariant mass of the two hadronic systems separated by the largest rapidity gap in the event. In this ξ range the scintillators are highly efficient. For diffractive events this corresponds to cases where at least one proton dissociates to a system with M X > 13 GeV . The measured cross section is compared with a range of theoretical predictions. When extrapolated to the full phase space, a cross section of 78.1 ± 2.9 mb is measured, consistent with the inelastic cross section increasing with center-of-mass energy.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurement of differential cross sections and W + / W &#x2212; cross-section ratios for W boson production in association with jets at s = 8 TeV with the ATLAS detector

This paper presents a measurement of the W boson production cross section and the W+/W- cross-section ratio, both in association with jets, in proton-proton collisions at sqrt(s) = 8 TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is performed in final states containing one electron and missing transverse momentum using data corresponding to an integrated luminosity of 20.2 fb^-1. Differential cross sections for events with at least one or two jets are presented for a range of observables, including jet transverse momenta and rapidities, the scalar sum of transverse momenta of the visible particles in the event, and the transverse momentum of the W boson. For a subset of the observables, the differential cross sections of positively and negatively charged W bosons are measured separately. In the cross-section ratio of W+/W- the dominant systematic uncertainties cancel out, improving the measurement precision by up to a factor of nine. The observables and ratios selected for this paper provide valuable input for the up quark, down quark, and gluon parton distribution functions of the proton.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Multi-Differential Charged Current 𝝂_𝝁− Argon Cross Section without Pions in the Final State Measurement in MicroBooNE , and Current Status of Simultaneous Cross Section Extraction with ANNIE

MicroBooNE, an 85-tonne liquid argon time projection chamber detector is on-axis to the Booster Neutrino Beam (BNB) at Fermi National Accelerator Laboratory. MicroBooNE is elucidating neutrino interactions with argon through cross-section measurements to refine interaction models and reduce uncertainties. In this poster, we present recent published single and double multi-differential charged current (CC) cross section with zero pions in the final state (CC-0 ) as a function of muon momentum ( ) and the cosine of the muon angle ( ). We present the details of the event selection and the extraction of 1D and 2D cross sections. We further report on the status of a simultaneous cross-section extraction conducted in conjunction with the ANNIE experiment, which employs a Gd-H O target and operates on the same BNB beamline. This joint measurement enables a precision test of nuclear A-dependence between oxygen and argon, with shared flux and cross-section model correlations leading to the cancellation of systematic uncertainties.

Nguyen, Christian Van [Rutgers U., Piscataway] (OR↗
NASA NTRS1975

A design method for entrance sections of transonic wind tunnels with rectangular cross sections

A mathematical technique developed to design entrance sections for transonic or high-speed subsonic wind tunnels with rectangular cross sections is discribed. The transition from a circular cross-section setting chamber to a rectangular test section is accomplished smoothly so as not to introduce secondary flows (vortices or boundary-layer separation) into a uniform test stream. The results of static-pressure measurements in the transition region and of static and total-pressure surveys in the test section of a pilot model for a new facility at the Ames Research Center are presented.

Lionel, L.↗
NASA NTRS1983

Subsonic high-angle-of-attack aerodynamic characteristics of a cone and cylinder with triangular cross sections and a cone with a square cross section

Experiments were conducted in the 12-Foot Pressure Wind Tunnel at Ames Research Center on three models with noncircular cross sections: a cone having a square cross section with rounded corners and a cone and cylinder with triangular cross sections and rounded vertices. The cones were tested with both sharp and blunt noses. Surface pressures and force and moment measurements were obtained over an angle of attack range from 30 deg to 90 deg and selected oil-flow experiments were conducted to visualize surface flow patterns. Unit Reynolds numbers ranged from 0.8x1,000,000/m to 13.0x1,000,000/m at a Mach number of 0.25, except for a few low-Reynolds-number runs at a Mach number of 0.17. Pressure data, as well as force data and oil-flow photographs, reveal that the three dimensional flow structure at angles of attack up to 75 deg is very complex and is highly dependent on nose bluntness and Reynolds number. For angles of attack from 75 deg to 90 deg the sectional aerodynamic characteristics are similar to those of a two dimensional cylinder with the same cross section.

Clarkson, M. H.↗