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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Thermodynamic origin of the pressure-induced Invar effect: General criterion and experimental study of Fe 68 ⁢Pd 32

Synchrotron X-ray diffraction measurements were performed on 57 Fe 68 Pd 32 at multiple pressures and two temperatures in a diamond-anvil cell. Between 4 and 11GPa, the thermal expansion was zero or slightly negative. This pressure-induced Invar effect was studied further with 57 Fe nuclear forward scattering and nuclear resonant inelastic X-ray scattering to obtain information on the pressure-induced changes in both the magnetization and the phonon density of states. Magnetic entropy and phonon entropy were obtained from these results, the latter with additional measurements from inelastic neutron scattering to account for the contributions from Pd atoms. The dependencies of these entropies on pressure gave the magnetic and phonon contributions to thermal expansion. These canceled in the region of pressure-induced Invar behavior, even though they individually increased by more than a factor of 2 below the Curie pressure. The behavior of phonons gives evidence for spin-phonon interactions in Fe 68 Pd 32 . A general explanation of the pressure-induced Invar effect is presented, showing that Invar behavior is typically expected at a pressure P* below a magnetic transition at pressure PC. The difference in pressure P C − P* scales with the fractional reduction in magnetic exchange interaction divided by the average Gr¨uneisen parameter.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Summary of light-element evaluation work: nuclear data uncertainty quantification

Hale & Paris (T-2) have evaluated the 15 N system to provide nuclear cross section and covariance information for nuclear data uncertainty quantification. This memo gives a brief discussion of the R-matrix method used to generate this nuclear scattering and reaction data in the ENDF-6 format.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1994

HST ultraviolet spectropolarimetry of NGC 1068

We present multiaperture spectropolarimetric observations of the Seyfert 2 galaxy NGC 1068. The nuclear region of NGC 1068 was observed with three apertures (4.3 sec x 1.4 sec., 1.0 sec., and 0.3 sec.) by the Hubble Space Telescope (HST). These ultraviolet data allow us to study the scattered, nuclear light without the complication of polarization dilution caused by strong unpolarized starlight. In particular, we can determine the mechanism of the scattering and the size scale of the scattering region. Our data confirm the findings of Antonicci & Miller (1985) and Code et al. (1993). Shortward of 2700 A, the continuum polarization is constant, P is approximately 16%, at a position angle of 97 deg, indicating electron scattering as the mechanism for the polarization. In addition, the narrow-line emission is much less polarized than the continuum, and two broad lines, Mg II lambda lambda 2796, 2804 and C III lambda 1909, are seen in polarized flux Ly-alpha and C IV are not included in our spectral region). The total flux data also indicate that from approximately 2200 A to approximately 3000 A, the spectrum of NGC 1068 is strongly affected by blended Fe II emission. These polarimetry data are explained by the occulation/reflection model proposed by Antonucci & Miller (1985). According to this model, NGC 1068 harbors a Seyfert 1 nucleus which is obscured along the line of sight by an opaque torus. The symmetry axis of the torus is alinged with the radio axis. Radiation from the broad-line region and feature continuum source can escape along the poles of the torus where it is scattered to us. This scattered light receives a partial linear polarization, perpendicular to the symmetry axis of the torus. Our measurements of the relative fluxes and polarized fluxes in the three apertures indicated that the scattering region is spatially extended on a scale of approximatley 1 sec. Also, in the 0.3 sec aperture, and to a lesser extent in the 1.0 sec aperture, the polarization is is somewhat higher, and the position angle somewhat lower, than in largest aperture. Presumably, isolating the central part of the relecting region results in less geometrical cancellation of the polarization and an angle indicative of the location of the innermost scattering paricles.

Antonucci, Robert↗
DOE OSTI2026

The Development of Kinetic and Radiation Hydrodynamics Modeling of Thermonuclear Burn Propagation in Isochoric p - 11 B Through the Support of the INFUSE Program

The report summarizes DOE INFUSE-supported work between HB11 Energy and the University of Rochester’s TriForce Institute to improve computational modeling of advanced fusion fuels, especially proton–boron-11 (p- 11 B). The project extended the TriForce particle-in-cell/Monte Carlo collision code to include physics needed for dense, high-temperature p- 11 B burn studies, including p- 11 B fusion reactions, three-alpha-particle reaction products, relativistic Coulomb collisions, large-angle nuclear scattering, bremsstrahlung radiation, inverse bremsstrahlung absorption, and photon transport. The upgraded models were verified against focused physics tests and against known deuterium–tritium burn behavior. The study then used one-dimensional spherical simulations to estimate the conditions required for thermonuclear burn propagation in isochoric p- 11 B fuel. The calculations found that burn propagation is possible in the model, but only under very extreme hot-spot conditions, such as about 7000 g/cm 3 at 500 keV or 9000 g/cm 3 at 300 keV for a 20-micron hot spot. These conditions are much more demanding than current demonstrated inertial confinement fusion hot spots. The report concludes that the INFUSE collaboration successfully advanced kinetic and radiation modeling capabilities for p- 11 B fusion and provided useful estimates of ignition requirements. However, the simulated fuel gains remain below what would be needed for practical inertial fusion energy, and further work is needed to reconcile differences among kinetic, radiation-hydrodynamic, and analytic models and to identify more achievable target designs.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Installation and Commissioning of the SBC-LAr10 Detector at Fermilab

This report describes the progress towards a scalable detector capable of quasi-background-free detection of sub-keV nuclear recoils under DOE award DE-SC0024254. Work supported by this award follows two distinct thrusts: (1) the first calibration of sensitivity to sub-keV nuclear recoils in a liquid-noble bubble chamber, based on data taken in a prototype liquid xenon bubble chamber run previously at Northwestern University, and (2) the successful assembly and installation of the 10-kg liquid argon bubble chamber SBC-LAr10 in the MINOS underground area at Fermilab. These accomplishments have paved the way for the precision calibration of SBC-LAr10 in the MINOS underground area at Fermilab in the coming year, which will use novel calibration techniques to measure the potential of the liquid noble bubble chamber technology for the detection of GeV-scale dark matter particles and the measurement of coherent elastic nuclear scattering by reactor anti-neutrinos (CEvNS).

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

A Review of Advanced Characterization Methods and Techniques for Amorphous and Poorly Crystalline Materials Applicable to Cementitious Waste Forms

This review covers advanced characterization methods of cementitious materials. The particular focus is to understand cementitious compositions with amorphous content because conventional techniques such as X-ray diffraction are more applicable to materials with long range order. Also of interest is advanced characterization that provides deeper insights into properties such as porosity. There are five groups of characterization methods discussed in this review which are: electron beam/microscopy, X-ray, neutron diffraction and scattering, nuclear magnetic resonance, and optical techniques. The techniques can be further grouped by the categories of nanoscale structural understanding (transmission electron microscopy and pair distribution function), microscale structural understanding (focused ion beam and x-ray tomography), microscopic elemental distributions (energy dispersive spectroscopy and X-ray fluorescence), and chemical binding information (electron energy loss spectroscopy, x-ray absorption spectroscopy, nuclear magnetic resonance, Raman spectroscopy, and infrared spectroscopy), with advantages and disadvantages of each method discussed. The recommendation for further research is to begin with techniques that are easier to prepare samples for, measure, and analyze, such as the optical techniques of Raman and infrared spectroscopy. If more information is needed, pursue collaborations, other techniques, or proposals for beam time at the synchrotron sources.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1990

Extended X-ray emission in nearby Seyfert galaxies

Asymmetric extended X-ray emission was found to be present in three out of five Seyfert galaxies. This paper discusses various possible origins for this emission, including thermal bremsstrahlung, synchrotron radiation, inverse Compton scattering, and electron-scattered nuclear radiation. It was found that the presently available data cannot discriminate definitively between these possibilities.

Elvis, Martin↗
NASA NTRS2007

The Suzaku Observation of the Nucleus of the Radio Loud Active Galaxy Centaurus A: Constraints on Abundances in the Accreting Material

A Suzaku observation of the nucleus of the radio-loud AGN Centaurus A in 2005 has yielded a broadband spectrum spanning 0.3 to 250 keV. The hard X-rays are fit by two power laws, absorbed by columns of 1.5 and 7 x 10(exp 23) per square centimeter. The dual power-laws are consistent with previous suggestions that the powerlaw components are X-ray emission from the sub-pc VLBI jet and from Bondi accretion at the core, or are consistent with a partial covering interpretation. The soft band is dominated by thermal emission from the diffuse plasma and is fit well by a two-temperature VAPEC model, plus a third power-law component to account for scattered nuclear emission, kpc-scale jet emission, and emission from X-ray Binaries and other point sources. Narrow fluorescent emission lines from Fe, Si, S, Ar, Ca and Ni are detected. The width of the Fe Ka line yields a 200 light-day lower limit on the distance from the black hole to the line-emitting gas. K-shell absorption edges due to Fe, Ca, and S are detected. Elemental abundances are constrained via the fluorescent lines strengths, absorption edge depths and the diffuse plasma emission lines. The high metallicity ([Fe/H]=+0.l) of the circumnuclear material compared to that in the metal-poor outer halo suggests that the accreting material could not have originated in the outer halo unless enrichment by local star formation has occurred. Relative abundances are consistent with enrichment from Type II and Ia supernovae.

Markowitz, A.↗
DOE OSTI2025

Constraints on magnetism and correlations in RuO 2 from lattice dynamics and Mössbauer spectroscopy

We provide experimental evidence for the absence of a magnetic moment in bulk RuO 2 , a candidate altermagnetic material, by using a combination of Mössbauer spectroscopy, nuclear forward scattering, inelastic X-ray and neutron scattering, and density functional theory calculations. Using complementary Mössbauer and nuclear forward scattering, we determine the Ru magnetic hyperfine splitting to be negligible. Inelastic X-ray and neutron scattering-derived lattice dynamics of RuO 2 are compared to density functional theory calculations of varying flavors. Comparisons among theory with experiments indicate that electronic correlations, rather than magnetic order, are key in describing the lattice dynamics.

Mössbauer spectroscopy↗
DOE OSTI2025

Parameterizations of electron scattering form factors for elastic scattering and electroexcitation of nuclear states in 27 Al and 40 Ca

Here, we report on empirical parameterizations of longitudinal ($\mathscr{R}$ L ) and transverse ($\mathscr{R}$ T ) nuclear elec- tromagnetic form factors for elastic scattering and the excitations of nuclear states in 27 Al and 40 Ca. The parameterizations are needed for the calculations of radiative corrections in measurements of electron scattering cross sections on 27 Al and 40 Ca in the quasi-elastic, resonance and inelastic con- tinuum regions, provide the contribution of nuclear excitations in investigations of the Coulomb Sum Rule, and test theoretical model predictions for excitation of nuclear states in electron and neutrino interactions on nuclear targets at low energies.

elastic scattering reactions↗
DOE OSTI2024

Structural properties of plastically deformed SrTiO 3 and KTaO 3

Dislocation engineering has the potential to open new avenues toward the exploration and modification of the properties of quantum materials. Strontium titanate (SrTi⁢O 3 , STO) and potassium tantalate (KTa⁢O 3 , KTO) are incipient ferroelectrics that show metallization and superconductivity at extremely low charge-carrier concentrations and have been the subject of resurgent interest. These materials also exhibit remarkable ambient-temperature ductility, and thus represent exceptional platforms for studies of the effects of deformation-induced dislocation structures on electronic properties. Recent work on plastically deformed STO revealed an enhancement of the superconducting transition temperature and the emergence of local ferroelectricity and magnetism near self-organized dislocation walls. Here, in this work, we present a comprehensive structural analysis of plastically deformed STO and KTO, employing specially designed strain cells, diffuse neutron and x-ray scattering, Raman scattering, and nuclear magnetic resonance (NMR). Diffuse scattering and NMR provide insight into the dislocation configurations and densities and their dependence on strain. As in the prior work on STO, Raman scattering reveals evidence for local ferroelectric order near dislocation walls in plastically deformed KTO. Our findings provide valuable information about the self-organized defect structures in both materials, and they position KTO as a second model system in which to explore the associated emergent physics.

36 MATERIALS SCIENCE↗
NASA NTRS1990

Inclusive inelastic scattering of heavy ions and nuclear correlations

Calculations of inclusive inelastic scattering distributions for heavy ion collisions are considered within the high energy optical model. Using ground state sum rules, the inclusive projectile and complete projectile-target inelastic angular distributions are treated in both independent particle and correlated nuclear models. Comparisons between the models introduced are made for alpha particles colliding with He-4, C-12, and O-16 targets and protons colliding with O-16. Results indicate that correlations contribute significantly, at small momentum transfers, to the inelastic sum. Correlation effects are hidden, however, when total scattering distributions are considered because of the dominance of elastic scattering at small momentum transfers.

Cucinotta, Francis A.↗
DOE OSTI2026

Active learning emulators for nuclear two-body scattering in momentum space

In this work we extend the active learning emulators for two-body scattering in coordinate space with error estimation, recently developed by Maldonado et al. [Phys. Rev. C 112, 024002], to coupled-channel scattering in momentum space. Our full-order model (FOM) solver is based on the Lippmann-Schwinger integral equation for the scattering t-matrix as opposed to the radial Schrödinger equation. We use (Petrov-)Galerkin projections and high-fidelity calculations at a few snapshots across the parameter space of the interaction to construct efficient reduced-order models (ROMs), trained by a greedy algorithm for locally optimal snapshot selection. Both the FOM solver and the corresponding ROMs are implemented efficiently in Python using Google's JAX library. We present results for emulating scattering phase shifts in coupled and uncoupled channels and cross sections, and assess the accuracy of the developed ROMs and their computational speedup factors. We also develop emulator error estimation for both the t-matrix and the total cross section. The software framework for reproducing and extending our results is publicly available. Together with our recent advances in developing active-learning emulators for three-body scattering, these emulator frameworks set the stage for full Bayesian calibrations of chiral nuclear interactions and optical models against scattering data with quantified emulator errors.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Greedy emulators for nuclear two-body scattering

Applications of reduced basis method emulators are increasing in low-energy nuclear physics because they enable fast and accurate sampling of high-fidelity calculations, enabling robust uncertainty quantification. Here, in this paper, we develop, implement, and test two model-driven emulators based on the (Petrov-)Galerkin projection using the prototypical test case of two-body scattering with the Minnesota potential and a more realistic local chiral potential. The high-fidelity scattering equations are solved with the matrix Numerov method, a reformulation of the popular Numerov recurrence relation for solving special second-order differential equations as a linear system of coupled equations. A novel error estimator based on reduced-space residuals is applied to an active learning approach (a greedy algorithm) to choosing training samples (“snapshots”) for the emulator and contrasted with a proper orthogonal decomposition (POD) approach. Both approaches allow for computationally efficient offline-online decompositions, but the greedy approach requires many fewer snapshot calculations. These developments set the groundwork for emulating scattering observables based on chiral nucleon-nucleon and three-nucleon interactions and optical models, where computational speed-ups are necessary for Bayesian uncertainty quantification. Our emulators and error estimators are widely applicable to linear systems.

Bayesian methods↗
DOE OSTI2025

Neutron Total Scattering Analysis of Materials for the Nuclear Fuel Cycle

Here, this paper reviews recent experimental efforts at the University of Tennessee and Oak Ridge National Laboratory to comprehensively characterize the structural details of materials relevant for the nuclear fuel cycle by employing advanced neutron scattering techniques. For the study of nuclear ceramics, neutron scattering offers distinct advantages over traditional laboratory or synchrotron X-ray diffraction, including enhanced sensitivity to elements with a low atomic mass, such as oxygen, nitrogen, and carbon. The key to these efforts is the recent advancement in the neutron scattering infrastructure at the high-flux diffractometers at the Spallation Neutron Source. The high neutron flux at these instruments enables neutron total scattering, a nondestructive bulk technique that simultaneously captures both short-range structural effects through pair distribution function analysis and long-range order through diffraction pattern analysis. This approach is particularly important for a comprehensive description of defective, disordered, or amorphous nuclear materials. The case studies presented here include analyses of the local defect structure in hyperstoichiometric uranium oxides and short-range order of ion-irradiated ceramics. This advanced analytical methodology will improve our understanding of the behavior of materials in extreme environments and contribute to the development of more resilient nuclear materials.

Neutron scattering↗