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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 1,801 records · Page 100
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Use of Biosurfactants in Oil Recovery

Biosurfactant-mediated oil recovery has the potential to recover large amounts of crude oil that remain entrapped in oil reservoirs after current oil recovery technologies reach their economic limit. Lipopeptides (surfactins and lichenysins), rhamnolipids, and other glycolipids generate the low interfacial tensions and the appropriate rock wettabilities needed to mobilize entrapped oil. Biosurfactants are active over a wide range of temperatures, pH values, and salinities found in many oil reservoirs and are effective at low concentrations. A number of laboratory experiments show that biosurfactant-mediated oil recovery is effective in recovering large amounts of entrapped oil. Several field trials show that in situ biosurfactant production is possible and recovers additional oil. Biosurfactant-mediated oil recovery has been difficult to scale-up to a reservoir-wide technology due to the lack of understanding of how best to stimulate biosurfactant production in the reservoir. In addition, the relationship between biosurfactant concentration and oil recovery is still unclear. Ex-situ biosurfactant-mediated oil recovery where the biosurfactant is added to the injection fluids has not been implemented on a large scale, most likely due to the high production costs of biosurfactants. Multidisciplinary approaches are needed to move biosurfactant-mediated oil recovery from the laboratory to the reservoir.

02 PETROLEUM↗
DOE OSTI2015

Search for charged Higgs bosons decaying via H ± → τ ± ν in fully hadronic final states using pp collision data at s $$ \sqrt{s} $$ = 8 TeV with the ATLAS detector

The results of a search for charged Higgs bosons decaying to a τ lepton and a neutrino, H ± → τ ± ν, are presented. The analysis is based on 19.5 fb –1 of proton-proton collision data at √s = 8 TeV collected by the ATLAS experiment at the Large Hadron Collider. Charged Higgs bosons are searched for in events consistent with top-quark pair production or in associated production with a top quark, depending on the considered H ± mass. The final state is characterized by the presence of a hadronic τ decay, missing transverse momentum, b-tagged jets, a hadronically decaying W boson, and the absence of any isolated electrons or muons with high transverse momenta. The data are consistent with the expected background from Standard Model processes. A statistical analysis leads to 95% confidence-level upper limits on the product of branching ratios Β(t → bH ± ) × Β(H ± → τ ± ν), between 0.23% and 1.3% for charged Higgs boson masses in the range 80-160GeV. It also leads to 95% confidence-level upper limits on the production cross section times branching ratio, σ(pp → tH ± + X) × Β(H ± → τ ± ν), between 0.76 pb and 4.5 fb, for charged Higgs boson masses ranging from 180 GeV to 1000 GeV. In the context of different scenarios of the Minimal Supersymmetric Standard Model, these results exclude nearly all values of tan β above one for charged Higgs boson masses between 80 GeV and 160 GeV, and exclude a region of parameter space with high tan β for H ± masses between 200 GeV and 250 GeV.

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↗
DOE OSTI2016

Measurement of the angular coefficients in Z-boson events using electron and muon pairs from data taken at $ \sqrt{s}=8 $ TeV with the ATLAS detector

The angular distributions of Drell-Yan charged lepton pairs in the vicinity of the Z-boson mass peak probe the underlying QCD dynamics of Z-boson production. This paper presents a measurement of the complete set of angular coefficients A 0–7 describing these distributions in the Z-boson Collins-Soper frame. The data analysed correspond to 20.3 fb –1 of pp collisions at √s = 8 TeV, collected by the ATLAS detector at the CERN LHC. The measurements are compared to the most precise fixed-order calculations currently available (O(α2s)) and with theoretical predictions embedded in Monte Carlo generators. The measurements are precise enough to probe QCD corrections beyond the formal accuracy of these calculations and to provide discrimination between different parton-shower models. A significant deviation from the (O(α 2 s )) predictions is observed for A 0 – A 2 . In conclusion, evidence is found for non-zero A 5,6,7 , consistent with expectations.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Erratum to: Search for supersymmetry in final states with two same-sign or three leptons and jets using 36 fb -1 of $ \sqrt{s} $ = 13 TeV pp collision data with the ATLAS detector

One correction is made to the figure 4e of the paper. The reported cross-sections, both the experimental upper limits and the theoretical prediction, corresponded only to a fiducial region of the phase space with at least two prompt same-sign electrons or muons before detector simulation (p T > 10 GeV, |η| < 2.8). The updated figure 4e instead presents the results without this requirement, i.e. in the full phase space as it should, given the y-axis label of the plot. The reported sensitivity of the analysis, i.e. the ability to exclude top squark masses below 700 GeV in this scenario, is however unchanged since the same requirements were applied to the analysis and to the theory predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using $\sqrt{s}=8 $ TeV proton-proton collision data

A search for squarks and gluinos in final states containing high-p T jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in $ \sqrt{s} $ = 8 TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb -1 . Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330 GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850 GeV (440 GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan β = 30, A 0 = -2m 0 and μ > 0, squarks and gluinos of equal mass are excluded for masses below 1700 GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

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