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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Measurement of the $B_s^0$ Lifetime in the Flavor-Specific Decay Channel $B_s^0 \to D_s^- \mu^+\nu X$

We present an updated measurement of the B s 0 lifetime using the semileptonic decays B s 0 → D s - μ + ν X , with D s - → ϕ π - and ϕ → K + K - (and the charge conjugate process). This measurement uses the full Tevatron Run II sample of proton-antiproton collisions at s = 1.96 TeV , comprising an integrated luminosity of 10.4 fb − 1 . We find a flavor-specific lifetime τ fs ( B s 0 ) = 1.479 ± 0.010 ( stat ) ± 0.021 ( syst ) ps . This technique is also used to determine the B 0 lifetime using the analogous B 0 → D - μ + ν X decay with D - → ϕ π - and ϕ → K + K - , yielding τ ( B 0 ) = 1.534 ± 0.019 ( stat ) ± 0.021 ( syst ) ps . Both measurements are consistent with the current world averages, and the B s 0 lifetime measurement is one of the most precise to date. Taking advantage of the cancellation of systematic uncertainties, we determine the lifetime ratio τ fs ( B s 0 ) / τ ( B 0 ) = 0.964 ± 0.013 ( stat ) ± 0.007 ( syst ) .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Measurement of the direct CP asymmetry in B¯->Xs+dy decays with a lepton tag

We report the measurement of the direct CP asymmetry in the radiative B¯?Xs+d? decay using a data sample of (772±11)×106 BB¯ pairs collected at the ?(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. The CP asymmetry is measured as a function of the photon energy threshold. For E*?=2.1 GeV, where E*? is the photon energy in the center-of-mass frame, we obtain ACP(B¯?Xs+d?)=(2.2±3.9±0.9)%, consistent with the Standard Model prediction.

Pesantez, L↗
DOE OSTI2015

First Observation of the Hadronic Transition Υ ( 4 S ) → η h b ( 1 P ) and New Measurement of the h b ( 1 P ) and η b ( 1 S ) Parameters

Using a sample of 771.6 × 10 6 Υ Υ ( 4 S ) decays collected by the Belle experiment at the KEKB e + e - collider, we observe, for the first time, the transition Υ ( 4 S ) → η h b ( 1 P ) with the branching fraction B [ Υ ( 4 S ) → η h b ( 1 P ) ] = ( 2.18 ± 0.11 ± 0.18 ) × 10 - 3 and we measure the h b ( 1 P ) mass M h b ( 1 P ) = ( 9899.3 ± 0.4 ± 1.0 ) MeV / c 2 , corresponding to the hyperfine (HF) splitting Δ M HF ( 1 P ) = ( 0.6 ± 0.4 ± 1.0 ) MeV / c 2 . Using the transition h b ( 1 P ) → γ η b ( 1 S ) , we measure the η b ( 1 S ) mass M η b ( 1 S ) = ( 9400.7 ± 1.7 ± 1.6 ) MeV / c 2 , corresponding to Δ M HF ( 1 S ) = ( 59.6 ± 1.7 ± 1.6 ) MeV / c 2 , the η b ( 1 S ) width Γ η b ( 1 S ) = ( 8 - 5 + 6 ± 5 ) MeV / c 2 and the branching fraction B [ h b ( 1 P ) → γ η b ( 1 S ) ] = ( 56 ± 8 ± 4 ) % .

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 the τ Lepton Polarization and R ( D * ) in the Decay B ¯ → D * τ - ν ¯ τ

Here, we discuss the first measurement of the τ lepton polarization P τ ( D * ) in the decay B ¯ → D * τ - ν ¯ τ as well as a new measurement of the ratio of the branching fractions R ( D * ) = B ( B ¯ → D * τ - ν ¯ τ ) / B ( B ¯ → D * ℓ - ν ¯ ℓ ) , where ℓ - denotes an electron or a muon, and the τ is reconstructed in the modes τ - → π - ν τ and τ - → ρ - ν τ . We use the full data sample of 772 × 1 0 6 B B ¯ pairs recorded with the Belle detector at the KEKB electron-positron collider. Our findings, P τ ( D * ) = - 0.38 ± 0.51 ( stat ) - 0.16 + 0.21 ( syst ) and R ( D * ) = 0.270 ± 0.035 ( stat ) - 0.025 + 0.028 ( syst ) , are consistent with the theoretical predictions of the standard model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

A Method to Estimate the Atomic Number and Mass Thickness of Intervening Materials in Uranium and Plutonium Gamma-Ray Spectroscopy Measurements

To accurately characterize shielded special nuclear materials (SNM) using passive gamma-ray spectroscopy measurement techniques, the effective atomic number and the thickness of shielding materials must be measured. Intervening materials between the source and detector may affect the estimated source isotopics (uranium enrichment and plutonium grade) for techniques which rely on raw count rates or photopeak ratios of gamma-ray lines separated in energy. Furthermore, knowledge of the surrounding materials can provide insight regarding the configuration of a device containing SNM. The described method was developed using spectra recorded using high energy resolution CdZnTe detectors, but can be expanded to any gamma-ray spectrometers with energy resolution of better than 1% FWHM at 662 keV. The effective atomic number, Z, and mass thickness of the intervening shielding material are identified by comparing the relative attenuation of different gamma-ray lines and estimating the proportion of Compton scattering interactions to photoelectric absorptions within the shield. While characteristic Kα x-rays can be used to identify shielding materials made of high Z elements, this method can be applied to all shielding materials. This algorithm has adequately estimated the effective atomic number for shields made of iron, aluminum, and polyethylene surrounding uranium samples using experimental data. The mass thicknesses of shielding materials have been estimated with a standard error of less than 1.3 g/cm2 for iron shields up to 2.5 cm thick. The effective atomic number was accurately estimated to 26 ± 5 for all iron thicknesses.

CdZnTe detectors, gamma-ray imaging, gamma-ray spe↗
DOE OSTI2018

Assessing Gaussian Assumption of PMU Measurement Error Using Field Data

Gaussian PMU measurement noise has been assumed for many power system applications, such as state estimation, oscillatory modes monitoring, voltage stability analysis, to cite a few. This letter proposes a simple yet effective approach to validate this assumption by using the stability property of a probability distribution and the concept of redundant measurement. Extensive results using field PMU data from WECC system reveal that the Gaussian assumption is questionable.

Wang, Shaobu (ORCID:0000000236073573)↗
DOE OSTI2017

Photonic Doppler velocimetry probe used to measure grain boundaries of dynamic shocked materials

Material scientists have developed computational modeling to predict the dynamic response of materials undergoing stress, but there is still a need to make precision measurements of surfaces undergoing shock compression. Miniature photonic Doppler velocimetry (PDV) probes have been developed to measure the velocity distribution from a moving surface traveling tens of kilometers per second. These probes use hundreds of optical fibers imaged by optical relays onto different regions of this moving surface. While previous work examined large surface areas, we have now developed a PDV microscope that can interrogate 37 different spots within a field of view of <1 mm, with a standoff distance of 17 mm, to analyze the motion differences across grain boundaries of the material undergoing dynamic stress. Each PDV fiber interrogates a 10 μm spot size on the moving surface. A separate imaging system using a coherent bundle records the location of the PDV spots relative to the grain boundaries prior to the dynamic event. Designing the mounting structures for the lenses, fibers, and coherent bundle was a challenge. To minimize back reflections, the fibers are index matched onto the first relay lens, which is made of fused silica. The PDV fibers are aligned normal to the moving surface. The imaging probe views the surface at an 18° angle. The coherent bundle is tilted 11° to its optical relay. All components are assembled into a single probe head assembly. The coherent bundle is removed from the probe head to be used for the next dynamic event. Alignment issues will also be discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Rheo-electric measurements of carbon black suspensions containing polyvinylidene difluoride in N -methyl-2-pyrrolidone

Lithium-ion battery cathode slurries have a microstructure that depends sensitively on how they are processed due to carbon black's (CB) evolving structure when subjected coating flows. While polyvinylidene difluoride (PVDF), one of the main components of the cathode slurry, plays an important role in modifying the structure and rheology of CB, a quantitative understanding is lacking. In this work, we explore the role of PVDF in determining the structural evolution of Super C65 CB in N-methyl-2-pyrrolidinone (NMP) with rheo-electric measurements. We find that PVDF enhances the viscosity of NMP resulting in a more extensive structural erosion of CB agglomerates with increasing polymer concentration and molecular weight. We also show that the relative viscosity of all suspensions can be collapsed by the fluid Mason number (Mnf), which compares the hydrodynamic forces imposed by the medium to cohesive forces holding CB agglomerates together. Using simultaneous rheo-electric measurements, we find at high Mnf, the dielectric strength (Δε) scales with Mnf, and the power-law scaling can be quantitatively predicted by considering the self-similar break up of CB agglomerates. The collapse of the relative viscosity and scaling of Δε both suggest that PVDF increases the hydrodynamic force of the suspending medium without directly changing the CB agglomerate structure. These findings are valuable for optimizing the rheology of lithium ion battery cathode slurries. We also anticipate that these findings can be extended to understand the microstructure of similar systems under flow.

Mechanics↗
DOE OSTI2014

Measurements of spin observables in pseudo-scalar meson photo-production using polarized neutrons in solid HD

A measurement of psuedo-scalar meson photo production from longitudinally polarized solid HD has been carried out with the CLAS at Thomas Jefferson National Accelerator Facility (Jlab) with circularly and linearly polarized photon beams. Its aim is to measure a complete set of spin observables for the neutron simultaneously from the same experiment. As a polarized neutron, deutron in HD was used. Preliminary asymmetries are shown for the π{sup −} channel.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Rapidity gap cross sections measured with the ATLAS detector in pp collisions at $\sqrt{s} = 7 \mbox{~TeV}$

Pseudorapidity gap distributions in proton-proton collisions at s√=7 ~TeVs=7 ~TeV are studied using a minimum bias data sample with an integrated luminosity of 7.1 μb -1 . Cross sections are measured differentially in terms of Δη F , the larger of the pseudorapidity regions extending to the limits of the ATLAS sensitivity, at η= ±4.9, in which no final state particles are produced above a transverse momentum threshold p$cut\atop{T}$ . The measurements span the region 0<Δη F < 8 for 200~MeV< p$cut\atop{T}$ <800~MeV200~MeV F , the data test the reliability of hadronisation models in describing rapidity and transverse momentum fluctuations in final state particle production. The measurements at larger gap sizes are dominated by contributions from the single diffractive dissociation process (pp→Xp), enhanced by double dissociation (pp→XY) where the invariant mass of the lighter of the two dissociation systems satisfies M Y ≲7 GeV. The resulting cross section is dσ/dΔη F ≈1 mb for Δη F ≳3. The large rapidity gap data are used to constrain the value of the Pomeron intercept appropriate to triple Regge models of soft diffraction. Finally, the cross section integrated over all gap sizes is compared with other LHC inelastic cross section measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Measurement of τ polarization in W→τν decays with the ATLAS detector in pp collisions at $\sqrt{s} =7~\mathrm{TeV}$

Here in this paper, a measurement of τ polarization in W→τν decays is presented. It is measured from the energies of the decay products in hadronic τ decays with a single final state charged particle. The data, corresponding to an integrated luminosity of 24 pb -1 , were collected by the ATLAS experiment at the Large Hadron Collider in 2010. The measured value of the τ polarization is P τ = -1.06 ± 0.04 (stat)$+0.05\atop{-0.07}$ (syst), in agreement with the Standard Model prediction, and is consistent with a physically allowed 95 % CL interval [-1,-0.91]. Measurements of τ polarization have not previously been made at hadron colliders.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurement of k T splitting scales in W→ℓν events at $\sqrt{s} = 7\ \mathrm{TeV}$ with the ATLAS detector

A measurement of splitting scales, as defined by the k T clustering algorithm, is presented for final states containing a W boson produced in proton–proton collisions at a centre-of-mass energy of 7 TeV. The measurement is based on the full 2010 data sample corresponding to an integrated luminosity of 36 pb -1 which was collected using the ATLAS detector at the CERN Large Hadron Collider. Cluster splitting scales are measured in events containing W bosons decaying to electrons or muons. The measurement comprises the four hardest splitting scales in a k T cluster sequence of the hadronic activity accompanying the W boson, and ratios of these splitting scales. Backgrounds such as multi-jet and top-quark-pair production are subtracted and the results are corrected for detector effects. Predictions from various Monte Carlo event generators at particle level are compared to the data. Overall, reasonable agreement is found with all generators, but larger deviations between the predictions and the data are evident in the soft regions of the splitting scales.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Measurement of the muon reconstruction performance of the ATLAS detector using 2011 and 2012 LHC proton–proton collision data

This study presents the performance of the ATLAS muon reconstruction during the LHC run with pp collisions at √s = 7–8 TeV in 2011–2012, focusing mainly on data collected in 2012. Measurements of the reconstruction efficiency and of the momentum scale and resolution, based on large reference samples of J/ψ → μμ, Z → μμ and Υ → μμ decays, are presented and compared to Monte Carlo simulations. Corrections to the simulation, to be used in physics analysis, are provided. Over most of the covered phase space (muon |η| < 2.7 and 5 ≲ p T ≲ 100 GeV) the efficiency is above 99% and is measured with per-mille precision. The momentum resolution ranges from 1.7% at central rapidity and for transverse momentum p T ≃ 10 GeV, to 4% at large rapidity and p T ≃ 100 GeV. The momentum scale is known with an uncertainty of 0.05% to 0.2% depending on rapidity. A method for the recovery of final state radiation from the muons is also presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

A measurement of the ratio of the production cross sections for W and Z bosons in association with jets with the ATLAS detector

In this study, the ratio of the production cross sections for W and Z bosons in association with jets has been measured in proton–proton collisions at √s = 7TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is based on the entire 2011 dataset, corresponding to an integrated luminosity of 4.6fb –1 . Inclusive and differential cross-section ratios for massive vector bosons decaying to electrons and muons are measured in association with jets with transverse momentum p T > 30GeV and jet rapidity |y| < 4.4. The measurements are compared to next-to-leading-order perturbative QCD calculations and to predictions from different Monte Carlo generators implementing leading-order matrix elements supplemented by parton showers.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗