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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Nucleon axial form factor from elementary target data

Precise neutrino-nucleon amplitudes are essential ingredients for predicting neutrino event rates in current and upcoming long-baseline neutrino oscillation experiments. A common neutrino interaction with a low reaction threshold and with most of the energy carried by two final state particles is quasielastic scattering, for which the nucleon axial form factor, 𝐹 𝐴⁡ (𝑄 2 ), is a dominant source of uncertainty. Improvements to the nucleon axial form factor rely on neutrino scattering data with elementary targets to reduce or eliminate the need for nuclear modeling systematics. This work examines constraints on the nucleon axial form factor that can be achieved from datasets of neutrino scattering on deuterium targets, Lattice QCD predictions, and from the recent hydrogen target data from the MINERvA Collaboration. Significant tension is found between hydrogen and deuterium target data, suggesting that extractions from deuterium underestimate both the central value and uncertainty of the form factor. Parametrizations for and uncertainties of the nucleon axial form factor using the 𝑧 expansion are provided.

FOS: Physical sciences↗
DOE OSTI2022

Biochemical and structural insights into SARS-CoV-2 polyprotein processing by Mpro

SARS-CoV-2, a human coronavirus, is the causative agent of the COVID-19 pandemic. Its genome is translated into two large polyproteins subsequently cleaved by viral papain-like protease and main protease (Mpro). Polyprotein processing is essential yet incompletely understood. We studied Mpro-mediated processing of the nsp7-11 polyprotein, whose mature products include cofactors of the viral replicase, and identified the order of cleavages. Integrative modeling based on mass spectrometry (including hydrogen-deuterium exchange and cross-linking) and x-ray scattering yielded a nsp7-11 structural ensemble, demonstrating shared secondary structural elements with individual nsps. The pattern of cross-links and HDX footprint of the C145A Mpro and nsp7-11 complex demonstrate preferential binding of the enzyme active site to the polyprotein junction sites and additional transient contacts to help orient the enzyme on its substrate for cleavage. Last, proteolysis assays were used to characterize the effect of inhibitors/binders on Mpro processing/inhibition using the nsp7-11 polyprotein as substrate.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Thermal neutron scattering measurements and modeling of yttrium-hydrides for high temperature moderator applications

In this work, thermal neutron scattering measurements of yttrium hydride from 5 to 1,200 K were conducted to determine the change in inelastic scattering as a function of temperature and to probe for anharmonic effects. Additionally, measurements on samples of YH x from x = 1.62 to 1.90 were done to determine the effects of varying hydrogen concentration on the inelastic spectra. Changes in temperature affected the inelastic spectra in unanticipated ways, indicating that there are anharmonic effects, whereas hydrogen concentration did not significantly affect the inelastic spectra. These measurements were compared against the ENDF/B-VIII.0 thermal scattering files of YH 2 , as well as new thermal scattering files created by using the stochastic temperature-dependent effective potential (s-TDEP). Both libraries were found to be in good agreement with the experimental data at lower temperatures. At higher temperatures, the s-TDEP method is better at predicting the experimentally observed softening of phonon modes in acoustic and optical regions.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Nucleon axial-vector form factor and radius from radiatively corrected antineutrino scattering data

The nucleon axial-vector form factor, 𝐺 𝐴 , is critical to determine the electroweak interactions of leptons with nucleons. Important examples of processes influenced by 𝐺 𝐴 are elastic (anti)neutrino-nucleon scattering and muon capture by the proton. Sparse experimental data results in a large uncertainty on the momentum dependence of 𝐺 𝐴 and has motivated the consideration of new experimental probes and first-principles lattice quantum chromodynamics (QCD) evaluations. The comparison of new and precise theoretical predictions for 𝐺 𝐴 with future experimental data necessitates the application of radiative corrections to experimentally observable processes. We apply these corrections in the extraction of 𝐺 𝐴 and the associated axial-vector radius from the recent MINERvA antineutrino-hydrogen data, compare the effects from radiative corrections to other uncertainties in neutrino scattering experiments, and discuss the comparison of lattice QCD evaluations to experimental measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Probing Self-Assembly in Arginine–Oleic Acid Solutions with Terahertz Spectroscopy and X-ray Scattering

A study of the formation of microstructures in the reaction of oleic acid with arginine elucidates dynamical self-assembly processes at the molecular level. Terahertz spectroscopy combined with density functional calculations reveals the initial hydrogen-bonding motifs in the assembly process, leading to the formation of micelles and vesicles. Small-angle X-ray scattering measurements allow for kinetic analysis of the growth processes of these nanostructures, revealing a prenucleation pathway of vesicles and micelles which lead to spongelike structures. This final stage of the assembly into spongelike aggregates is investigated with optical microscopy. The formed structures only occur at pH > 8 and are resistant to extreme acidic and basic conditions. Here, a mechanistic pathway to the formation of the spongelike aggregates is described.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Small-pore hydridic frameworks store densely packed hydrogen

Nanoporous materials have attracted great attention for gas storage, but achieving high volumetric storage capacity remains a challenge. Here, by using neutron powder diffraction, volumetric gas adsorption, inelastic neutron scattering and first-principles calculations, we investigate a magnesium borohydride framework that has small pores and a partially negatively charged non-flat interior for hydrogen and nitrogen uptake. Hydrogen and nitrogen occupy distinctly different adsorption sites in the pores, with very different limiting capacities of 2.33 H 2 and 0.66 N 2 per Mg(BH 4 ) 2 . Molecular hydrogen is packed extremely densely, with about twice the density of liquid hydrogen (144 g H 2 per litre of pore volume). We found a penta-dihydrogen cluster where H 2 molecules in one position have rotational freedom, whereas H 2 molecules in another position have a well-defined orientation and a directional interaction with the framework. This study reveals that densely packed hydrogen can be stabilized in small-pore materials at ambient pressures.

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

Lattice dynamics of high-pressure hydrides studied by inelastic neutron scattering

Due to the small mass and anomalously large neutron scattering cross-section of proton (about 80 barns compared to a few barns for other nuclei), inelastic neutron scattering is considered as one of the most effective tools in studying optical vibrations of hydrogen atoms in metal hydrides. The current review is focused on the binary hydrides of 3d- and 4d-metals of groups VI–VIII, which were produced at high hydrogen pressures of several gigapascals in relatively large quantities of hundreds of mg, quenched to low temperature and studied by INS ex situ at ambient pressure with high statistical accuracy. One of the unusual effects revealed by INS is a strong increase in the strength of the metal-hydrogen interactions with decreasing atomic number of the d-metal accompanied by an increase in the Me-H distance. Based on the available experimental results, the spectra g(E) of the phonon density of states and temperature dependencies CV(T) of the heat capacity at constant volume at T up to 1000 K have been derived in this paper and presented both in the figures and in digital form. This provides the reference data for the theoretical investigations of the crystal structures and compositions of new practically important hydrides giving the opportunity to validate calculation methods by comparing the calculated g(E) and CV(T) with the accurate experimental dependencies for the binary hydrides. Recent INS studies showed [R.A. Klein et al., J. Alloy. Compd. 894 (2022) 162381] that the fingerprints of anomalously short H-H separations of 1.6 Å violating the “2 Å rule” can be easily and unambiguously identified in the complex INS spectra of quaternary hydrides (La,Ce)NiInH 1+x . This makes neutron spectroscopy an attractive means for obtaining valuable data in the search for novel hydrides with a record high hydrogen capacity.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

The MUSE beamline calorimeter

The MUon Scattering Experiment (MUSE) was motivated by the proton radius puzzle arising from the discrepancy between muonic hydrogen spectroscopy and electron–proton measurements. The MUSE physics goals also include testing lepton universality, precisely measuring two-photon exchange contribution, and testing radiative corrections. MUSE addresses these physics goals through simultaneous measurement of high precision cross sections for electron–proton and muon–proton scattering using a mixed-species beam. The experiment will run at both positive and negative beam polarities. Measuring precise cross sections requires understanding both the incident beam energy and the radiative corrections. For this purpose, a lead-glass calorimeter was installed at the end of the beam line in the MUSE detector system. Here, in this article, we discuss the detector specifications, calibration and performance. We demonstrate that the detector performance is well reproduced by simulation, and meets experimental requirements.

Calorimeter↗
DOE OSTI2022

Pressure cells for in situ neutron total scattering: time and real-space resolution during deuterium absorption

In situ gas-loading sample holders for two-dimensionally arranged detectors in time-of-flight neutron total scattering experiments have been developed to investigate atomic arrangements during deuterium absorption using time and real-space resolution. A single-crystal sapphire container was developed that allows conditions of 473 K and 10 MPa hydrogen gas pressure. High-resolution transient measurements detected deuterium absorption by palladium that proceeded within a few seconds. A double-layered container with thick- and thin-walled vanadium allowed conditions of 423 K and 10 MPa hydrogen gas pressure. The deuterium occupation sites of a lanthanum–nickel–aluminium alloy are discussed in detail on the basis of real-space high-resolution data obtained from in situ neutron scattering measurements and reverse Monte Carlo structural modeling.

08 HYDROGEN↗
DOE OSTI2024

Reversible hydrogen storage in multilayer graphane: Lattice dynamics, compressibility, and heat capacity studies

Multilayer graphane (hydride of graphite) is a crystalline hydrocarbon of composition CH, which can be synthesized from graphite and molecular hydrogen at pressures above 2GPa [V.E. Antonov et al. Carbon 100 (2016) 465]. Using X-ray diffraction, this compound was tentatively identified as the “graphane II” phase of 3D-graphane predicted by ab initio calculations [X.-D. Wen et al. PNAS 108 (2011) 6833] and consisting of layers of 2D-graphane in the “chair” conformation. When heated in a vacuum, the compound does not form any intermediate hydrocarbons and reversibly decomposes back into graphite and hydrogen at 770–920 K. In the present work, almost single-phase samples of graphite hydride and deuteride were synthesized at 7.4 GPa and 870 K. Their investigation by inelastic neutron scattering supplemented by ab initio calculations gave spectra g(E) of the phonon density of states with a gap of about 15 meV at approx. 100 meV, which is a unique identifier for the chair form of graphane. The equation of state V(P) of the hydride was studied at room temperature and hydrogen pressures up to 53 GPa by synchrotron X-ray diffraction in a diamond anvil cell. Further, the graphane II phase did not react with the surrounding hydrogen and did not undergo any phase transformations upon the compression and after heating to 1500 K at 53GPa. The high thermal and pressure stability of this exotic phase makes it an important part of the C–H system. The obtained g(E) spectra of graphite hydride and deuteride were used to calculate temperature dependences of their heat capacity. Measurements of the heat capacity at temperatures 120–673 K confirmed the good accuracy of these calculations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

High-pressure synthesis and neutron scattering study of tantalum hydride TaH 1.23(5) and a tantalum polymorph with A15-type structure

A unique type of tantalum hydride was synthesized by exposing tantalum dihydride to the high hydrogen pressure of 9 GPa and a temperature of using toroid-type high-pressure chambers. The samples of this hydride were cooled down to 100 K, recovered to ambient pressure, and studied in a metastable state by hot extraction, powder x-ray and neutron diffraction, and inelastic neutron scattering. X-ray diffraction demonstrated that this hydride had an A15-type crystal structure of metal lattice (space group , Ta atoms at the 2a and 6c Wyckoff positions) and a lattice parameter of a = 5.150(5) Å at T = 85 K. The hydrogen content determined by hot extraction was H/Ta - 1.23(5). Hydrogen desorption during heating the sample in vacuum proceeded in two steps—first, Δ⁢H⁡/Ta=0.2 was desorbed at around -70 °⁢C, and then the rest of the hydrogen was desorbed between 100 ⁢°C and 390 ⁢°⁢C. The A⁢15-type metal lattice was preserved upon hydrogen removal, leaving a unique polymorph of tantalum. Neutron diffraction of A⁢15-TaH 1.23⁢(5) demonstrated that hydrogen atoms occupy the 24⁢k and 16⁢i Wyckoff sites in the crystal structure, and annealing at 250 K resulted in a decrease of the 24⁢k and an increase of the 16⁢i site occupancies. Inelastic neutron scattering revealed four vibrational modes in the fundamental band of A⁢15-TaH 1.23⁢(5) at 72, 135, 145, and 166 meV, the first three and the last one of which were tentatively assigned to the vibrations of H atoms at the 24⁢k and 16⁢i sites, respectively. No superconductivity was found in A⁢15-TaH 1.1 and hydrogen-free A15-Ta at temperatures down to 1.5 K.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Total thermal neutron cross section measurements of hydrogen dense polymers from 0.0005–20 eV

Hydrogen dense polymers, specifically polyethylene, polystyrene, and Plexiglas, have served as neutron moderator and reflector materials in hundreds of separate critical benchmark experiments because of their low cost and abundance of hydrogen. In order to accurately model and simulate these critical benchmarks, the thermal scattering law (TSL) evaluation that governs how neutrons will thermalize must be well understood and rigorously validated. To support this validation, researchers at Rensselaer Polytechnic Institute performed total neutron cross section measurements for high-density polyethylene & polystyrene over the energy range 0.0005–20 eV and for Plexiglas G & Plexiglas G-UVT over the energy range 0.0005–3 eV. Comparisons were made between the measured cross section and that predicted by the ENDF/B-VIII.0 and Oak Ridge National Laboratory/European Spallation Source/Rensselaer Polytechnic Institute TSL evaluations for polyethylene, Plexiglas, and polystyrene, as available. These experiments represent the first total neutron cross section measurements for polystyrene.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Micro-segregation phenomena and related spectroscopic signals in melt-grown β-Ga2O3 single crystals

One of the primary advantages of β-Ga2O3 over incumbent wide bandgap semiconductors is the ability to grow directly from the melt. Melt growth, using Czochralski or similar methods, results in impurities in the crystal which originate from the crucible, such as iridium and other transition metals like chromium. These impurities exhibit optoelectronic signatures useful for their identification and sensitive to the Fermi energy of a given crystal (i.e., signatures vary with the electrical conductivity of the matrix). In this work, we describe how laser Raman systems can be used to map and spatially correlate Cr3+ photoluminescence, electronic-coupled Raman scattering from Ir4+d–d internal transitions, and the Raman line attributed to hydrogenic shallow donors. Laser ablation inductively coupled plasma mass spectrometry directly measured spatially dependent relative metal concentrations and confirmed spectroscopic signals resulting from heterogeneities in impurity concentrations in β-Ga2O3 boules. Mapping of photoluminescence and Raman-related signatures is, thus, demonstrated as an effective and facile method for spatial measurement of chemical heterogeneities in both insulating and conductive melt-grown β-Ga2O3 crystals.

Dutton, Benjamin L. (ORCID:000000031272130X)↗
DOE OSTI2023

Exploring the gravitational structure of the proton with the dilepton final state using the CLAS12 detector at Jefferson Lab

The Gravitational Form Factors (GFFs) give access to the internal distributions of mass, pressure and shear force inside the proton. They were considered experimentally unmeasurable for decades due to the very weak gravitational interaction [1]. However, the Generalized Parton Distributions (GPDs), which describe the correlations between the longitudinal momentum and the transverse position of the partons inside the nucleon, have lately been related to the GFFs. For the first time, this relation gives the opportunity to extract GFFs experimentally. In this talk, I will present two ways to access GFFs using data taken in 2018 by the CLAS12 detector with a 10.6 GeV electron beam impinging on a liquid-hydrogen target. First, I will present the first measurement of the Timelike Compton Scattering reaction (the hard photoproduction of a lepton pair), that gives access to the quark GFFs via the angular asymmetry of the electron/positron pair [2]. I will then present the current effort to extract the near-threshold J/? photoproduction cross section using the same dataset. This later measurement is expected to provide direct insight on the gluons GFFs of the proton. [1] H. PAGELS. Energy-Momentum Structure Form Factors of Particles. Phys.Rev. 144 (1966) 1250-1260 [2] P. Chatagnon. First Measurement of Timelike Compton Scattering. Phys.Rev.Lett. 127 (2021) 26, 262501

Chatagnon, Pierre↗
DOE OSTI2023

Phonon-informed Neural Thermal Scattering (NeTS) Optimization for Crystalline Graphite and Beryllium Metal

Fast neutrons born from fission lose energy through scattering interactions in the process of slowing-down. As neutrons thermalize to the order of $k$ $b$ $T$ (where $k$ $b$ is the Boltzmann constant, and $T$ is the temperature of the medium), their de Broglie wavelength and energy approaches the order of inter-atomic spacing and quantized lattice vibrations, i.e., phonons. At thermal energies, the thermal scattering law (TSL), i.e., $S$($α, β$), captures crystal binding contributions to the total reaction rate, or cross section. This dimensionless material property describes the energy ($β$) and momentum ($α$) exchanges available in a medium. Currently, $S$($α, β$) is evaluated in the Full Law Analysis Scattering System Hub (FLASSH) code for discrete inputs and stored as ENDF/B File 7 for 0-phonon elastic (MT 2) and n-phonon inelastic (MT 4) processes. Further processing recasts $S$($α, β$) into cumulative distribution functions for sampling post-collision scattering kinematics. In practice, interpolation schemes are employed to access data between tabulated values. An improvement to this juncture of the nuclear data pipeline is supplying cross sections on-the-fly (OTF), as has been developed for the un-resolved resonance region to minimize non-physical interpolation errors. This capability may improve simulation accuracy for accident and transient analyses, where rapidly varying changes in temperature and pressure are difficult to predict beforehand. To do so, deep artificial neural networks (ANNs) can be employed which collapse non-linear, complex data into a lightweight dictionary of neural weights and biases. This has been successfully demonstrated for the hydrogen in light water $S$($α, β$) dataset in the form of a Neural Thermal Scattering (NeTS) module. In this work, the NeTS framework is extended to consider the impact of material-dependent dynamical features on optimal neural pre-processing and architecture design decisions, such as number of neurons per hidden layer, residual skip connections and neural depth. New NeTS modules for crystalline graphite and beryllium metal illuminate a novel correlation between dynamical nonlinearity and optimal neural parametrization when deploying $S$($α, β$) on-the-fly.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Experimental Study of the Fundamental Properties of Warm Dense Mixtures

The aim of the proposed research was to provide a multi-scale study of the properties of warm dense hydrocarbons, by studying the thermodynamic properties through the equation of state and the microscopic properties by x-ray scattering. Understanding the fundamental properties of warm dense mixtures is an intellectual challenge due to the complexity of the system. Unlike liquids or gases, where constituent particle interactions occur through collisions or bonding between valence electrons, in these strongly coupled systems the atoms will be partially ionized and compressed so tightly together that interactions between the inner core electrons can play a role in the systems chemistry. Advances in computational capabilities and development of new theoretical models have been used to predict the properties of mixtures but there is currently no experimental data of the fundamental interaction between the particles in mixtures to test these predictions against. The proposed research was to experimentally investigate the interaction of the different species in hydrocarbons by measuring the compressibility of substances with different carbon and hydrogen ratios and the complexity of the microscopic interactions through elastic and inelastic x-ray scattering. To study the bulk properties of warm dense hydrocarbons we established the Warm Dense Matter Research Laboratory (WDMRL) in the Institute for Shock Physics at Washington State University. The goal was for experiments in the WDMRL to determine shock loading conditions of interest in the hydrocarbon mixtures. We planned on using Hugoniot EOS measurements and a range of carbon and hydrogen concentrations to determine conditions when the EOS of the mixture varied significantly from that of the classical mixing model. Even though shock transit measurements through aluminum foils suggested pressures upto 400GPa, the experiments in the WDMRL were unsuccessful in getting usable shockwave compression data above 100GPa in polystyrene which was below the pressure of interest for hydrocarbon mixtures (>200GPa). To complete the project, we tested a technique using x-ray phase contrast imaging to map the location of tracer layers in a test sample of polycarbonate to record the material motion in dynamically compressed samples. A technique that will be useful for future warm dense matter experiments. These experiments used <200nm gold layers in polycarbonate samples to measure the material velocity and shock speed using x-ray phase contrast imaging. These results were compared to continuum surface measurements performed at ISP and show that the tracer layer technique can measure hydrodynamic properties accurately in dynamically compressed materials.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Purification of Propylene and Ethylene by a Robust Metal–Organic Framework Mediated by Host–Guest Interactions

Industrial purification of propylene and ethylene requires cryogenic distillation and selective hydrogenation over palladium catalysts to remove propane, ethane and/or trace amounts of acetylene. Here, we report the excellent separation of equimolar mixtures of propylene/propane and ethylene/ethane, and of a 1/100 mixture of acetylene/ethylene by a highly robust microporous material, MFM-520, under dynamic conditions. In situ synchrotron single crystal X-ray diffraction, inelastic neutron scattering and analysis of adsorption thermodynamic parameters reveal that a series of synergistic host-guest interactions involving hydrogen bonding and π&ctdot;π stacking interactions underpin the cooperative binding of alkenes within the pore. Notably, the optimal pore geometry of the material enables selective accommodation of acetylene. The practical potential of this porous material has been demonstrated by fabricating mixed-matrix membranes comprising MFM-520, Matrimid and PIM-1, and these exhibit not only a high permeability for propylene (≈1984 Barrer), but also a separation factor of 7.8 for an equimolar mixture of propylene/propane at 298 K.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Molecular-scale origins of solution nanostructure and excess thermodynamic properties in a water/amphiphile mixture

The molecular and nanoscale origins of nonideality in excess thermodynamic properties are essential to understanding cosolvent mixtures, yet they remain challenging to determine. Here, we consider a binary mixture of water and an amphiphile, N,N,N',N'-tetramethylmalonamide (TMMA), which is characterized by strong hydrogen bonding between the two components and no hydrogen bonding between amphiphiles. Using molecular dynamics simulation, validated with excess volume measurements and X-ray scattering, we identify three distinct solution regimes across the composition range of the binary mixture and find that the transition between two of these regimes, marked by the water percolation threshold, is closely correlated with minima in the excess volume and excess enthalpy. Structural analysis of the simulations reveals an interplay between local interactions and solution nanostructure, determined by the relative strength of the water–water and water–amphiphile hydrogen bonding interactions. By comparison with other amphiphiles, such as linear alcohols, the relative strength of like and unlike interactions between water and amphiphile affects the relationship between thermodynamics and structural regimes. This provides insight into how molecular forces of mutual solvation interact across length scales and how they manifest in excess thermodynamic properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗