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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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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Precision Measurement of Charged Pion and Kaon Differential Cross Sections in e + e - Annihilation at s = 10.52 GeV

Measurements of inclusive differential cross sections for charged pion and kaon production in e + e - annihilation have been carried out at a center-of-mass energy of s = 10.52 GeV . The measurements were performed with the Belle detector at the KEKB e + e - collider using a data sample containing 113 × 10 6 e + e - → q q ¯ events, where q = { u , d , s , c } . We present charge-integrated differential cross sections d σ h ± / d z for h ± = { π ± , K ± } as a function of the relative hadron energy z = 2 E h / s from 0.2 to 0.98. The combined statistical and systematic uncertainties for π ± ( K ± ) are 4% (4%) at z ~ 0.6 and 15% (24%) at z ~ 0.9 . The cross sections are the first measurements of the z dependence of pion and kaon production for z > 0.7 as well as the first precision cross section measurements at a center-of-mass energy far below the Z 0 resonance used by the experiments at LEP and SLC.

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↗
DOE OSTI2012

Measurement of the isolated diphoton cross section in p p collisions at s = 7 TeV with the ATLAS detector

Here, the ATLAS experiment has measured the production cross section of events with two isolated photons in the final state, in proton-proton collisions at √s = 7 TeV. The full data set acquired in 2010 is used, corresponding to an integrated luminosity of 37 pb –1 . The background, consisting of hadronic jets and isolated electrons, is estimated with fully data-driven techniques and subtracted. The differential cross sections, as functions of the di-photon mass (m γγ ), total transverse momentum (pT, γγ ), and azimuthal separation (ΔΦ γγ ), are presented and compared to the predictions of next-to-leading-order QCD.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Uncertainty Quantification in Fission Cross Section Measurements at LANSCE

Neutron-induced fission cross sections have been measured for several isotopes of uranium and plutonium at the Los Alamos Neutron Science Center (LANSCE) over a wide range of incident neutron energies. The total uncertainties in these measurements are in the range 3–5% above 100 keV of incident neutron energy, which results from uncertainties in the target, neutron source, and detector system. The individual sources of uncertainties are assumed to be uncorrelated, however correlation in the cross section across neutron energy bins are considered. The quantification of the uncertainty contributions will be described here.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Measurement of the cross section for the production of a W boson in association with b-jets in pp collisions at root s=7 TeV with the ATLAS detector

A measurement is presented of the cross section for the production of a W boson with one or two jets, of which at least one must be a b-jet, in pp collisions at {radical}s = 7 TeV. Production via top decay is not included in the signal definition. The measurement is based on 35 pb{sup -1} of data collected with the ATLAS detector at the LHC. The W + b-jet cross section is defined for jets reconstructed with the anti-kt clustering algorithm with transverse momentum above 25 GeV and rapidity within {+-}2.1. The b-jets are identified by reconstructing secondary vertices. The fiducial cross section is measured both for the electron and muon decay channel of the W boson and is found to be 10.2 {+-} 1.9(stat) {+-} 2.6(syst) pb for one lepton flavour. The results are compared with next-to-leading order QCD calculations, which predict a cross section smaller than, though consistent with, the measured value.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Measurements of the electron and muon inclusive cross-sections in proton-proton collisions at root s=7 TeV with the ATLAS detector

This Letter presents measurements of the differential cross-sections for inclusive electron and muon production in proton-proton collisions at a centre-of-mass energy of {radical}s = 7 TeV, using data collected by the ATLAS detector at the LHC. The muon cross-section is measured as a function of pT in the range 4 < pT < 100 GeV and within pseudorapidity |{eta}| < 2.5. In addition the electron and muon cross-sections are measured in the range 7 < pT < 26 GeV and within |{eta}| < 2.0, excluding 1.37 < |{eta}| < 1.52. Integrated luminosities of 1.3 pb{sup -1} and 1.4 pb{sup -1} are used for the electron and muon measurements, respectively. After subtraction of the W/Z/{gamma}{sm_bullet} contribution, the differential cross-sections are found to be in good agreement with theoretical predictions for heavy-flavour production obtained from Fixed Order NLO calculations with NLL high-pT resummation, and to be sensitive to the effects of NLL resummation.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Zirconium Nuclear Data Campaign: Measurement of 90 Zr ( n, γ ) Cross Section

The isotopes of Zr with A = [90, 91, 92, 94] make up more than 97% of naturally occurring Zr and are important to many nuclear applications such as nuclear reactors. One of the attractive qualities of naturally occurring Zr isotopes is that they have a low σ γ /σ t ratio at most neutron energies. Thus, they improve the neutron economy in reactors by preferentially scattering neutrons rather than absorbing them. This same quality also presents a challenge to measuring the capture cross section, σ γ , of Zr isotopes. The ENDF/B VIII.0 library has a relative uncertainty of approximately 10–20% for incident neutron energies < 0.1 MeV and an uncertainty greater than 20% for energies > 0.1 MeV for the majority of natural Zr isotopes. This motivated the Nuclear Criticality Safety Program to embark on a campaign to accurately measure and evaluate these Zr isotopes. In this work, we demonstrate energy-dependent neutron capture cross section measurements for the first enriched sample to be measured: 90 Zr.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2011

Measurements of single top quark production cross sections and |V tb | in pp̄ collisions at √s=1.96 TeV

We present measurements of production cross sections of single top quarks in pp̄ collisions at √s=1.96 TeV in a data sample corresponding to an integrated luminosity of 5.4 fb⁻¹ collected by the D0 detector at the Fermilab Tevatron Collider. We select events with an isolated electron or muon, an imbalance in transverse energy, and two, three, or four jets, with one or two of them containing a bottom hadron. We obtain an inclusive cross section of σ(pp̄→tb+X,tqb+X)=3.43± 0.73 0.74 pb and use it to extract the CKM matrix element 0.79<|V tb |≤1 at the 95% C.L. We also measure σ(pp̄→tb+X)=0.68±0.380.35 pb and σ(pp̄→tqb+X)=2.86± 0.69 0.63 pb when assuming, respectively, tqb and tb production rates as predicted by the standard model.

Abazov, V. M.↗
DOE OSTI2011

{sup 149}Sm(n,{alpha}){sup 146}Nd Cross Sections in the MeV Region

We have measured the {sup 149}Sm(n,{alpha}){sup 146}Nd cross section at 4.5, 5.0, 5.5, 6.0, and 6.5 MeV. Measurements were performed at the 4.5 MV Van de Graaff accelerator of Peking University with monoenergetic neutrons produced via the {sup 2}H(d,n){sup 3}He reaction using a deuterium gas target. Alpha particles were detected with a double-section gridded ionization chamber having two back-to-back {sup 149}Sm{sub 2}O{sub 3} samples attached to the common cathode. Absolute neutron flux was measured using a small {sup 238}U fission chamber and monitored by a BF{sub 3} long counter. These are the first reported cross sections for this reaction at these energies, except at 6.0 eV, where our new data are in good agreement with our earlier result. The present results help to much better constrain the {sup 149}Sm(n,{alpha}){sup 146}Nd cross section in a region where its energy dependence is changing fairly rapidly and there are large differences between evaluated nuclear data libraries.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Photoionization of Ne Atoms and Ne{sup +} Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

Single, double, and triple photoionization of Ne{sup +} ions by single photons have been investigated at the synchrotron radiation source PETRA III in Hamburg, Germany. Absolute cross-sections were measured by employing the photon–ion merged-beams technique. Photon energies were between about 840 and 930 eV, covering the range from the lowest-energy resonances associated with the excitation of one single K-shell electron up to double excitations involving one K- and one L-shell electron, well beyond the K-shell ionization threshold. Also, photoionization of neutral Ne was investigated just below the K edge. The chosen photon energy bandwidths were between 32 and 500 meV, facilitating the determination of natural line widths. The uncertainty of the energy scale is estimated to be 0.2 eV. For comparison with existing theoretical calculations, astrophysically relevant photoabsorption cross-sections were inferred by summing the measured partial ionization channels. Discussion of the observed resonances in the different final ionization channels reveals the presence of complex Auger-decay mechanisms. The ejection of three electrons from the lowest K-shell-excited Ne{sup +}(1s2s{sup 2}2p{sup 62}S{sub 1/2}) level, for example, requires cooperative interaction of at least four electrons.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Measurement of the inclusive jet cross-section in proton-proton collisions at $ \sqrt{s}=7 $ TeV using 4.5 fb -1 of data with the ATLAS detector

The inclusive jet cross-section is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV using a data set corresponding to an integrated luminosity of 4.5 fb -1 collected with the ATLAS detector at the Large Hadron Collider in 2011. Jets are identified using the anti-k t algorithm with radius parameter values of 0.4 and 0.6. The double-differential cross-sections are presented as a function of the jet transverse momentum and the jet rapidity, covering jet transverse momenta from 100 GeV to 2 TeV. Next-to-leading-order QCD calculations corrected for non-perturbative effects and electroweak effects, as well as Monte Carlo simulations with next-to-leading-order matrix elements interfaced to parton showering, are compared to the measured cross-sections. A quantitative comparison of the measured cross-sections to the QCD calculations using several sets of parton distribution functions is performed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Inclusive and differential measurements of the $\textrm{t}\overline{\textrm{t}}\mathcal{γ}$ cross section and the $\textrm{t}\overline{\textrm{t}}\mathcal{γ}/\textrm{t}\overline{\textrm{t}}$ cross section ratio in proton-proton collisions at $\sqrt{s}=13$ TeV

Inclusive and differential cross section measurements of top quark pair $(\textrm{t}\overline{\textrm{t}})$ production in association with a photon (γ) are performed as a function of lepton, photon, top quark, and $\textrm{t}\overline{\textrm{t}}$ kinematic observables, using data from proton-proton collisions at $\sqrt{s}=13$ TeV, corresponding to an integrated luminosity of 138 fb −1 , collected at the CERN LHC with the CMS detector. Events containing two leptons (electrons or muons) and a photon in the final state are considered. The fiducial cross section of $\textrm{t}\overline{\textrm{t}}$γ is measured to be 137 ± 8 fb, in a phase space including events with a high momentum, isolated photon. The fiducial cross section of $\textrm{t}\overline{\textrm{t}}$γ is also measured to be 56 ± 5 fb when considering only events where the photon is emitted in the production part of the process. Both measurements are in agreement with the theoretical predictions, of 126 ± 19 fb and 57 ± 5 fb, respectively. Differential measurements are performed at the particle and parton levels. Additionally, inclusive and differential ratios between the cross sections of $\textrm{t}\overline{\textrm{t}}$γ and $\textrm{t}\overline{\textrm{t}}$ production are measured. The inclusive ratio is found to be 0.0133 ± 0.0005, in agreement with the standard model prediction of 0.0127 ± 0.0008. The top quark charge asymmetry in $\textrm{t}\overline{\textrm{t}}$γ production is also measured to be −0.012 ± 0.042, compatible with both the standard model prediction and with no asymmetry.

Hadron-Hadron Scattering↗
DOE OSTI2014

Measurement of dijet cross-sections in pp collisions at 7 TeV centre-of-mass energy using the ATLAS detector

Double-differential dijet cross-sections measured in pp collisions at the LHC with a 7 TeV centre-of-mass energy are presented as functions of dijet mass and half the rapidity separation of the two highest-p T jets. These measurements are obtained using data corresponding to an integrated luminosity of 4.5 fb -1 , recorded by the ATLAS detector in 2011. The data are corrected for detector effects so that cross-sections are presented at the particle level. Cross-sections are measured up to 5TeV dijet mass using jets reconstructed with the anti- k t algorithm for values of the jet radius parameter of 0.4 and 0.6. The cross-sections are compared with next-to-leading-order perturbative QCD calculations by NLOJet++ corrected to account for non-perturbative effects. Comparisons with POWHEG predictions, using a next-to-leading-order matrix element calculation interfaced to a partonshower Monte Carlo simulation, are also shown. Electroweak effects are accounted for in both cases. The quantitative comparison of data and theoretical predictions obtained using various parameterizations of the parton distribution functions is performed using a frequentist method. In general, good agreement with data is observed for the NLOJet++ theoretical predictions when using the CT10, NNPDF2.1 and MSTW 2008 PDF sets. Disagreement is observed when using the ABM11 and HERAPDF1.5 PDF sets for some ranges of dijet mass and half the rapidity separation. An example setting a lower limit on the compositeness scale for a model of contact interactions is presented, showing that the unfolded results can be used to constrain contributions to dijet production beyond that predicted by the Standard Model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Differential top-antitop cross-section measurements as a function of observables constructed from final-state particles using pp collisions at $\sqrt{s}=7 $ TeV in the ATLAS detector

Various differential cross-sections are measured in top-quark pair (tt) events produced in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the LHC with the ATLAS detect or. These differential cross-sections are presented in a data set corresponding to an integrated luminosity of 4.6 fb -1 . The differential cross-sections are presented in terms of kinematic variables, such as momentum, rapidity and invariant mass, of a top-quark proxy referred to as the pseudo-top-quark as well as the pseudo-top-quark pair system. The dependence of the measurement on theoretical models is minimal. The measurements are performed on tt events in the lepton+jets channel, requiring exactly one charged lepton and at least four jets with at least two of them tagged as originating from a b-quark. The hadronic and leptonic pseudo-top-quarks are defined via the leptonic or hadronic decay mode of the W boson produced by the top-quark decay in events with a single charged lepton. Differential cross-section measurements of the pseudo-top-quark variables are compared with several Monte Carlo models that implement next-to-leading order or leading-order multi-leg matrix-element calculations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗