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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Measurement of the cross section for $\text{t}\bar{\text{t}}$ production with additional jets and b jets in pp collisions at $\sqrt{s}=$ 13 TeV

Measurements of the cross section for the production of top quark pairs in association with a pair of jets from bottom quarks $ \left({\sigma}_{\mathrm{t}\overline{\mathrm{t}}\mathrm{b}\overline{\mathrm{b}}}\right) $ and in association with a pair of jets from quarks of any flavor or gluons $ \left({\sigma}_{\mathrm{t}\overline{\mathrm{t}}\mathrm{jj}}\right) $ and their ratio are presented. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV by the CMS experiment at the LHC in 2016 and correspond to an integrated luminosity of 35.9 fb$^{−1}$. The measurements are performed in a fiducial phase space and extrapolated to the full phase space, separately for the dilepton and lepton+jets channels, where lepton corresponds to either an electron or a muon. The results of the measurements in the fiducial phase space for the dilepton and lepton+jets channels, respectively, are $ {\sigma}_{\mathrm{t}\overline{\mathrm{t}}\mathrm{jj}} $ = 2.36±0.02 (stat)±0.20 (syst) pb and 31.0±0.2 (stat)±2.9 (syst) pb, and for the cross section ratio 0.017 ± 0.001 (stat) ± 0.001 (syst) and 0.020 ± 0.001 (stat) ± 0.001 (syst). The values of $ {\sigma}_{\mathrm{t}\overline{\mathrm{t}}\mathrm{b}\overline{\mathrm{b}}} $ are determined from the product of the $ {\sigma}_{\mathrm{t}\overline{\mathrm{t}}\mathrm{jj}} $ and the cross section ratio, obtaining, respectively, 0.040±0.002 (stat)±0.005 (syst) pb and 0.62±0.03 (stat)±0.07 (syst) pb. These measurements are the most precise to date and are consistent, within the uncertainties, with the standard model expectations obtained using a matrix element calculation at next-to-leading order in quantum chromodynamics matched to a parton shower.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Microstructural characterization of as-fabricated monolithic plates with boron carbide, aluminum boride, and zirconium boride burnable absorbers

The use of burnable absorbers can be beneficial for nuclear reactors by extending the fuel’s operational cycle, providing additional criticality control, and flattening the power profile. In this work, three burnable absorber materials (boron carbide, aluminum boride, and zirconium boride) embedded in aluminum have been fabricated into foils and clad in AA-6061 for potential use in high performance research reactors. The as-fabricated boron-containing phases were determined using transmission electron microscopy to be AlB2, B4C, and ZrB2. TEM also revealed weak bonding at the B4C-matrix interface. SEM showed a relatively uniform spatial distribution of boron-containing phases for all the candidate materials. Higher porosity was observed in the foil containing ZrB2 in its as-rolled condition. The porosity in the ZrB2 foil was reduced by hot isostatic pressing. The size and shape distributions of the boron-containing phases were analyzed on the criteria of cross-sectional area, perimeter, roundness, circularity, and aspect ratio. A method of converting the 2D burnable absorber dispersoids seen in cross-sectional microscopy images into 3D volumes was derived using both spherical and ellipsoidal geometry models. The difference in calculated burnable absorber dispersoid average volume between the two models ranges from 20% to 100%, which could impact burnable absorber burnout rates due to differences in neutron self-shielding.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Exclusive four pion photoproduction in ultraperipheral Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

The intense photon fluxes from relativistic nuclei provide an opportunity to study photonuclear interactions in ultraperipheral collisions. The measurement of coherently photoproduced π + π − π + π − final states in ultraperipheral Pb–Pb collisions at √s NN = 5.02 TeV is presented for the first time. The cross section, dσ/dy, times the branching ratio (ρ →π + π + π − π − ) is found to be 47.8±2.3 (stat.)± 7.7 (syst.) mb in the rapidity interval |y| < 0.5. The invariant mass distribution is not well described with a single Breit-Wigner resonance. The production of two interfering resonances, ρ(1450) and ρ(1700), provides a good description of the data. The values of the masses (m) and widths (Γ) of the resonances extracted from the fit are m 1 = 1385±14 (stat.)±3 (syst.) MeV/c 2 , Γ 1 = 431±36 (stat.)±82 (syst.) MeV/c 2 , m 2 = 1663±13 (stat.)±22 (syst.) MeV/c 2 and Γ 2 = 357 ± 31 (stat.)±49 (syst.) MeV/c 2 , respectively. The measured cross sections times the branching ratios are compared to recent theoretical predictions.

FOS: Physical sciences↗
DOE OSTI2024

Enhanced Production of Λ b 0 Baryons in High-Multiplicity p p Collisions at s = 13 TeV

The production rate of Λ b 0 baryons relative to B 0 mesons in p p collisions at a center-of-mass energy s = 13 TeV is measured by the LHCb experiment. The ratio of Λ b 0 to B 0 production cross sections shows a significant dependence on both the transverse momentum and the measured charged-particle multiplicity. At low multiplicity, the ratio measured at LHCb is consistent with the value measured in e + e − collisions, and increases by a factor of ∼ 2 with increasing multiplicity. At relatively low transverse momentum, the ratio of Λ b 0 to B 0 cross sections is higher than what is measured in e + e − collisions, but converges with the e + e − ratio as the momentum increases. These results imply that the evolution of heavy b quarks into final-state hadrons is influenced by the density of the hadronic environment produced in the collision. Comparisons with several models and implications for the mechanisms enforcing quark confinement are discussed. © 2024 CERN, for the LHCb Collaboration 2024 CERN

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Search for $t\bar{t}H/A$ → $t\bar{t}t\bar{t}$ production in the multilepton final state in proton–proton collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

A search for a new heavy scalar or pseudo-scalar Higgs boson ($H/A$) produced in association with a pair of top quarks, with the Higgs boson decaying into a pair of top quarks ($H/A$ → $t\bar{t}$) is reported. The search targets a final state with exactly two leptons with same-sign electric charges or at least three leptons. The analysed dataset corresponds to an integrated luminosity of 139 fb –1 of proton–proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Two multivariate classifiers are used to separate the signal from the background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of a type-II two-Higgs-doublet model. The observed (expected) upper limits at 95% confidence level on the $t\bar{t}$$H/A$ production cross-section times the branching ratio of $H/A$ → $t\bar{t}$ range between 14 (10) fb and 6 (5) fb for a heavy Higgs boson with mass between 400 GeV and 1000 GeV, respectively. Assuming that only one particle, either the scalar $H$ or the pseudo-scalar $A$, contributes to the $t\bar{t}t\bar{t}$ final state, values of tan $β$ below 1.2 or 0.5 are excluded for a mass of 400 GeV or 1000 GeV, respectively. These exclusion ranges increase to tan $β$ below 1.6 or 0.6 when both particles are considered.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Search for heavy resonances in final states with four leptons and missing transverse momentum or jets in pp collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

A search for a new heavy boson produced via gluon-fusion in the four-lepton channel with missing transverse momentum or jets is performed. The search uses proton-proton collision data equivalent to an integrated luminosity of 139 fb -1 at a centre-of-mass energy of 13 TeV collected by the ATLAS detector between 2015 and 2018 at the Large Hadron Collider. This study explores the decays of heavy bosons: R → SH and A → ZH, where R is a CP-even boson, A is a CP-odd boson, H is a CP-even boson, and S is considered to decay into invisible particles that are candidates for dark matter. In these processes, S → invisible and H → ZZ. The Z boson associated with the heavy scalar boson H decays into all decay channels of the Z boson. The mass range under consideration is 390–1300 (320–1300) GeV for the R (A) boson and 220–1000 GeV for the H boson. No significant deviation from the Standard Model backgrounds is observed. The results are interpreted as upper limits at a 95% confidence level on the cross-section times the branching ratio of the heavy resonances.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Search for the production of a Higgs boson in association with a single top quark in pp collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

A search for the production of a Higgs boson in association with a single top quark, tH, is presented. The analysis uses proton-proton collision data corresponding to an integrated luminosity of 140 fb −1 at a centre-of-mass energy of 13 TeV, collected by the ATLAS detector at the LHC. The search targets Higgs-boson decays into $b\bar{b}$, WW * , ZZ * , and ττ, accompanied by an isolated lepton (electron or muon) from the top-quark decay. Multivariate techniques are employed to enhance the separation between signal and background processes. The observed signal strength, μ tH , defined as the ratio between the measured cross-section and the predicted Standard Model value, is μ tH = 8.1 ± 2.6 (stat.) ± 2.0 (syst.). The significance of the observed (expected) signal above the background-only expectation is 2.8 (0.4) standard deviations. The corresponding observed (expected) upper limit at the 95% confidence level on the tH cross-section is found to be 13.9 (6.1) times the value predicted by the Standard Model. An interpretation with an inverted sign of the top-quark Yukawa coupling is performed, and the signal strength and corresponding limit are reported.

Hadron-Hadron Scattering↗
DOE OSTI2024

Measurement of the VH,H → ττ process with the ATLAS detector at 13 TeV

A measurement of the Standard Model Higgs boson produced in association with a W or Z boson and decaying into a pair of τ-leptons is presented. This search is based on proton-proton collision data collected at $\sqrt{s}$ = 13 TeV by the ATLAS experiment at the LHC corresponding to an integrated luminosity of 140 fb -1 . For the Higgs boson candidate, only final states with at least one τ-lepton decaying hadronically (τ→hadrons+ν τ ) are considered. For the vector bosons, only leptonic decay channels are considered: Z→ℓℓ and W→ℓν ℓ , with ℓ=e,μ. An excess of events over the expected background is found with an observed (expected) significance of 4.2 (3.6) standard deviations, providing evidence of the Higgs boson produced in association with a vector boson and decaying into a pair of τ-leptons. The ratio of the measured cross-section to the Standard Model prediction is μ$_{VH}^{ττ}$=1.28$_{-0.29}^{+0.30}$(stat.)$_{-0.21}^{+0.25}$(syst.). This result represents the most accurate measurement of the VH(ττ) process achieved to date.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

A first principles method to determine speciation of carbonates in supercritical water

The determination of the speciation of ions and molecules in supercritical aqueous fluids under pressure is critical to understanding their mass transport in the Earth's interior. Unfortunately, there is no experimental technique yet available to directly characterize species dissolved in water at extreme conditions. Here we present a strategy, based on first-principles simulations, to determine ratios of Raman scattering cross-sections of aqueous species under extreme conditions, thus providing a key quantity that can be used, in conjunction with Raman measurements, to predict chemical speciation in aqueous fluids. Due to the importance of the Earth's carbon cycle, we focus on carbonate and bicarbonate ions. Our calculations up to 11 GPa and 1000 K indicate a higher concentration of bicarbonates in water than previously considered at conditions relevant to the Earth's upper mantle, with important implications for the transport of carbon in aqueous fluids in the Earth's interior.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Black carbon aerosol number and mass concentration measurements by picosecond short-range elastic backscatter lidar

Abstract Black carbon aerosol emissions are recognized as contributors to global warming and air pollution. There remains, however, a lack of techniques to remotely measure black carbon aerosol particles with high range and time resolution. This article presents a direct and contact-free remote technique to estimate the black carbon aerosol number and mass concentration at a few meters from the emission source. This is done using the Colibri instrument based on a novel technique, referred to here as Picosecond Short-Range Elastic Backscatter Lidar (PSR-EBL). To address the complexity of retrieving lidar products at short measurement ranges, we apply a forward inversion method featuring radiometric lidar calibration. Our method is based on an extension of a well-established light-scattering model, the Rayleigh–Debye–Gans for Fractal-Aggregates (RDG-FA) theory, which computes an analytical expression of lidar parameters. These parameters are the backscattering cross-sections and the lidar ratio for black carbon fractal aggregates. Using a small-scale Jet A-1 kerosene pool fire, we demonstrate the ability of the technique to quantify the aerosol number and mass concentration with centimetre range-resolution and millisecond time-resolution.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

A large field-of-view high-resolution hard x-ray microscope using polymer optics

Here, we present an effective approach using a matched pair of polymer-based condenser-objective lenses to build a compact full-field X-ray microscope with a high spatial resolution. A unique condenser comprising arrays of high-aspect-ratio prisms with equilateral cross-section is used for uniformly illuminating samples over a large field of view (FoV) from all angles, which match the acceptance of an objective made of interdigitated orthogonal rows of one-dimensional lenses. State-of-the-art Talbot grating interferometry used to characterize these lenses for the first time revealed excellent focusing properties and minimal wave-front distortions. Using a specific lens-pair designed for 20 keV X-rays, short-exposure times, and image registration with a cross-correlation technique, we circumvent vibrational instabilities to obtain distortion-free images with a uniform resolution of 240 nm (smallest resolvable line pair) over a large FoV, 80 × 80 µm 2 in extent. The results were contrasted with those collected under illumination using commercial two-dimensional parabolic lenses with a smaller FoV. This approach implemented on a diffractometer would enable diffraction-contrast or dark-field microscopy for fast observations of ‘mesoscopic’ phenomena in real space complementing reciprocal-space studies using diffraction on the same instrument.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Dean vortex-enhanced blood plasma separation in self-driven spiral microchannel flow with cross-flow microfilters

Point-of-care (POC) diagnostic devices have been developing rapidly in recent years, but they are mainly using saliva instead of blood as a test sample. A highly efficient self-separation during the self-driven flow without power systems is desired for expanding the point-of-care diagnostic devices. Microfiltration stands out as a promising technique for blood plasma separation but faces limitations due to blood cell clogging, resulting in reduced separation speed and efficiency. These limitations are mainly caused by the high viscosity and hematocrit in the blood flow. A small increment in the hematocrit of the blood significantly increases the pressure needed for the blood plasma separation in the micro-filters and decreases the separation speed and efficiency. Addressing this challenge, this study explores the feasibility of diluting whole blood within a microfluidic device without external power systems. This study implemented a spiral microchannel utilizing the inertial focusing and Dean vortex effects to focus the red blood cells and extract the blood with lower hematocrit. The inertial migration of the particles during the capillary flow was first investigated experimentally; a maximum of 88% of the particles migrated to the bottom and top equilibrium positions in the optimized 350 × 60 μm (cross-sectional area, 5.8 aspect ratio) microchannel. With the optimized dimension of the microchannel, the whole blood samples within the physiological hematocrit range were tested in the experiments, and more than 10% of the hematocrit reduction was compared between the outer branch outlet and inner branch outlet in the 350 × 60 μm microchannel.

Biochemistry & Molecular Biology↗
DOE OSTI2025

Building the case for forward muon detection at a muon collider

We survey the opportunities offered by the detection of the forward muons that accompany the creation of neutral effective vector bosons at a muon collider, in different kinematic regimes. Vectors with relatively low energy produce the Higgs boson and the extended muon angular coverage enables studies of the Higgs properties, such as the measurement of the inclusive production cross section and the branching ratio to invisible final states. New heavy particles could be produced by vectors of higher energy, through Higgs portal interactions. If the new particles are invisible, the detection of the forward muons is essential in order to search for this scenario. The angular correlations of the forward muons are sensitive to the quantum interference between the vector-boson helicity amplitudes and can be exploited for the characterization of vector-boson scattering and fusion processes. This is illustrated by analyzing the C P properties of the Higgs coupling to the Z boson. Our findings provide a physics case and a set of benchmarks for the design of a dedicated forward muon detector. Published by the American Physical Society 2025

Ruhdorfer, Maximilian (ORCID:0000000288973223)↗
DOE OSTI2022

Thermal properties of field-assisted-sintered SiCN–Y 2 O 3 composites

Polymer-derived amorphous SiCN has excellent high-temperature stability and properties. To reduce the shrinkage during pyrolysis and to improve the high-temperature oxidation resistance, Y 2 O 3 was added as a filler. In this study, polymer-derived SiCN–Y 2 O 3 composites were fabricated by mixing a polymeric precursor of SiCN with Y 2 O 3 submicron powders in different ratios. The mixtures were cross-linked and pyrolyzed in argon. SiCN–Y 2 O 3 composites were processed using field-assisted sintering technology at 1350°C for 5 min under vacuum. Dense SiCN–Y 2 O 3 composite pellets were successfully made with relative density higher than 98% and homogeneous microstructure. Due to low temperature and short time of the heat-treatment, the grain growth of Y 2 O 3 was substantially inhibited. The Y 2 O 3 grain size was ~1 μm after sintering. The composites’ heat capacity, thermal diffusivity, and thermal expansion coefficients were characterized as a function of temperature. The thermal conductivity of the composites ceramics decreased as the amount of amorphous SiCN increased and the coefficient of thermal expansion (CTE) of the composites increased with Y 2 O 3 content. However, the thermal conductivity and CTE did not follow the rule of mixture. This is likely due to the partial oxidation of SiCN and the resultant impurity phases such as Y 2 SiO 5 , Y 2 Si 2 O 7 , and Y 4.67 (SiO 4 ) 3 O.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Push—pull microring-assisted space-and-wavelength selective switch

We introduce a novel design of a space-and-wavelength selective switch based on microring-assisted Mach–Zehnder interferometers. Multiple pairs of overcoupled microring resonators are incorporated as efficient and narrowband phase shifters and are driven in push–pull scheme. We design and demonstrate a 2 × <#comment/> 2 × <#comment/> 2 λ <#comment/> elementary switch block with full spatial and spectral switching capabilities. The switching device’s cross talk suppression and extinction ratio both exceed 21 dB. We measure over 75 GHz optical bandwidth per channel and less than 1.5 dB power penalty at 10 − <#comment/> 9 BER when two 32 Gbps on–off keying signals are loaded simultaneously. This new class of switching elements can further enable compact and high-performance space-and-wavelength selective switch fabrics without the need for wavelength (de)multiplexers or parallel switching planes.

Huang, Yishen (ORCID:0000000278710462)↗
DOE OSTI2020

Kinemetrics Q330M+ Digitizer Evaluation

Sandia National Laboratories has tested and evaluated a new digitizer, the Q330M+, manufactured by Quanterra, a division of Kinemetrics Inc. This digitizer is used to record sensor output for seismic and infrasound monitoring applications. The purpose of the digitizer evaluation was to measure the performance characteristics in such areas as sensitivity, input impedance, power consumption, self noise, dynamic range, system noise, relative transfer function, analog bandwidth, modified noise power ratio, harmonic distortion, common mode, cross talk, timing tag accuracy and timing drift. The Q330M+ provides six channels of 24 bit digitization, all of which may be transmitted utilizing CD1.1 protocol, at multiple sample rates.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Charm production and fragmentation fractions at midrapidity in pp collisions at $\sqrt{\textrm{s}}$ = 13 TeV

Measurements of the production cross sections of prompt $D^{0}$, $D^{+}$, $D^{*+}$, $D^{+}_{s}$, $Λ^{+}_{c}$, and $Ξ^{+}_{c}$ charm hadrons at midrapidity in proton-proton collisions at $\sqrt{\textrm{s}}$ = 13 TeV with the ALICE detector are presented. The D-meson cross sections as a function of transverse momentum (p T ) are provided with improved precision and granularity. The ratios of p T -diferential meson production cross sections based on this publication and on measurements at diferent rapidity and collision energy provide a constraint on gluon parton distribution functions at low values of Bjorken-x (10 —5 –10 —4 ). The measurements of $Λ^{+}_{c}$ ($Ξ^{+}_{c}$) baryon production extend the measured p T intervals down to p T = 0(3) GeV/c. These measurements are used to determine the charm-quark fragmentation fractions and the $c$$\overline{c}$ production cross section at midrapidity (|$y$| < 0.5) based on the sum of the cross sections of the weakly-decaying ground-state charm hadrons $D^{0}$, $D^{+}$, $D^{+}_{s}$, $Λ^{+}_{c}$, and $Ξ^{0}_{c}$ and, for the first time, $Ξ^{+}_{c}$, and of the strongly-decaying J/ψ mesons. The frst measurements of $Ξ^{+}_{c}$and $Σ^{0,++}_{c}$ fragmentation fractions at midrapidity are also reported. A signifcantly larger fraction of charm quarks hadronising to baryons is found compared to e + e — and ep collisions. The $c$$\overline{c}$ production cross section at midrapidity is found to be at the upper bound of state-of-the-art perturbative QCD calculations

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Measurement of the top quark pair production cross section in PbPb collisions at $\sqrt{s_{\mathrm{NN}}}=5.36$ TeV

The inclusive cross section for top quark pair ($\mathrm{t}\overline{\mathrm{t}}$) production in lead-lead (PbPb) collisions is reported for the first time at a center-of-mass energy per nucleon pair of 5.36 TeV. The analysis uses data corresponding to an integrated luminosity of 1.58 nb −1 collected by the CMS experiment at the CERN LHC in 2023. The $\mathrm{t}\overline{\mathrm{t}}$ production cross section, ${\sigma}_{\mathrm{t}\overline{\mathrm{t}}}={3.42}_{-0.51}^{+0.54}{\left(\mathrm{stat}\right)}_{-0.43}^{+0.50}\left(\mathrm{syst}\right)$ μb, is measured in dilepton final states using a fit to a multivariate discriminator that combines the decay electron and muon kinematic properties with the multiplicity of bottom quark jets. The result is consistent with perturbative quantum chromodynamics calculations at next-to-next-to-leading order (NNLO) accuracy employing several nuclear parton distribution functions. In addition, the Drell–Yan production cross section (σ DY ) for dilepton masses above 10 GeV and the ratio of $\mathrm{t}\overline{\mathrm{t}}$ to DY cross sections $\left({R}_{\mathrm{t}\overline{\mathrm{t}}/\mathrm{DY}}\right)$ are found to be compatible with the NNLO predictions. The observables ${\sigma}_{\mathrm{t}\overline{\mathrm{t}}}$, σ DY , and ${R}_{\mathrm{t}\overline{\mathrm{t}}/\mathrm{DY}}$ are measured separately for central and semicentral PbPb collisions to investigate for the first time the dependence of top quark production on the collision impact parameter.

Heavy Ion Experiments↗