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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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Correlated, precision measurements of θ 23 and δ using only the electron neutrino appearance experiments

Precision measurement of the leptonic CP violating phase δ will suffer from the, then surviving, large uncertainty of sin 2 θ 23 of 10–20% in the experimentally interesting region near maximal mixing of θ 23 . We advocate a new method for determination of both θ 23 and δ at the same time using only the ν e and ν̄ e appearance channels and show that sin 2 θ 23 can be determined automatically with much higher accuracy, approximately a factor of six, than sinδ. In this method, we identify a new degeneracy for the simultaneous determination of θ 23 and δ, the θ 23 intrinsic degeneracy, which must be resolved in order to achieve precision measurement of these two parameters. Spectral information around the vacuum oscillation maxima is shown to be the best way to resolve this degeneracy.

Minakata, Hisakazu↗
DOE OSTI2018

Search for B-L R -parity-violating top squarks in $\sqrt{s}$=13TeV pp collisions with the ATLAS experiment

A search for direct pair production of top squarks in final states with two tau leptons, b -jets, and missing transverse momentum is presented. The analysis is based on proton-proton collision data at √s = 13 TeV corresponding to an integrated luminosity of 36.1 fb -1 recorded with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. Two exclusive channels with either two hadronically decaying tau leptons or one hadronically and one leptonically decaying tau lepton are considered. No significant deviation from the Standard Model predictions is observed in the data. The analysis results are interpreted in terms of model-independent limits and used to derive exclusion limits on the masses of the top squark $\tilde{t}_{1}$ and the tau slepton $\tilde{τ}_{1}$ in a simplified model of supersymmetry with a nearly massless gravitino. In this model, masses up to m ($\tilde{t}_{1}$) = 1.16 TeV and m ($\tilde{τ}_{1}$) = 1.00 TeV are excluded at 95% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Measurements of Electron Thermal Transport due to Electron Temperature Gradient Modes in a Basic Experiment

Production and identification of electron temperature gradient modes have already been reported [X. Wei, V. Sokolov, and A. K. Sen, Phys. Plasmas 17, 042108 (2010)]. Now a measurement of electron thermal conductivity via a unique high frequency triple probe yielded a value of {chi}{sub perpendiculare} ranging between 2 and 10 m{sup 2}/s, which is of the order of a several gyrobohm diffusion coefficient. This experimental result appears to agree with a value of nonlocal thermal conductivity obtained from a rough theoretical estimation and not inconsistent with gyrokinetic simulation results for tokamaks. The first experimental scaling of the thermal conductivity versus the amplitude of the electron temperature gradient fluctuation is also obtained. It is approximately linear, indicating a strong turbulence signature.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Search for resonances decaying to top and bottom quarks with the CDF experiment

We report on a search for charged massive resonances decaying to top (t) and bottom (b) quarks in the full data set of proton-antiproton collisions at a center-of-mass energy of √s = 1.96 TeV collected by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.5 fb –1 . No significant excess above the standard model background prediction is observed. We set 95% Bayesian credibility mass-dependent upper limits on the heavy charged-particle production cross section times branching ratio to tb. Using a standard model extension with a W' → tb and left-right-symmetric couplings as a benchmark model, we constrain the W' mass and couplings in the 300–900 GeV/c 2 range. As a result, the limits presented here are the most stringent for a charged resonance with mass in the range 300–600 GeV/c 2 decaying to top and bottom quarks.

Aaltonen, Timo Antero↗
DOE OSTI2018

Low-mass Dark Matter Search with the DarkSide-50 Experiment

We present the results of a search for dark matter WIMPs in the mass range below 20 GeV/c^2 using a target of low-radioactivity argon. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso (LNGS). The analysis is based on the ionization signal, for which the DarkSide-50 time projection chamber is fully efficient at 0.1 keVee. The observed rate in the detector at 0.5 keVee is about 1.5 events/keVee/kg/day and is almost entirely accounted for by known background sources. We obtain a 90% C.L. exclusion limit above 1.8 GeV/c^2 for the spin-independent cross section of dark matter WIMPs on nucleons, extending the exclusion region for dark matter below previous limits in the range 1.8-6 GeV/c^2.

Agnes, P↗