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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 1,531 records · Page 85
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Ninth International Workshop on Chiral Dynamics, 2018

The Ninth International Workshop on Chiral Dynamics (CD18) was hosted by the Triangle Universities Nuclear Laboratory (TUNL) and held on the campus of Duke University in Durham, NC. The workshop was from September 17 th to 21 st , 2018. This series of workshops, which started at MIT in 1994, brings together theorists and experimentalists every three years to discuss the status and challenges in the physics of low-energy quantum chromodynamics (QCD), Goldstone Boson dynamics, meson-baryon interactions, few-body physics, lattice QCD and Chiral Perturbation Theory. The last workshop was jointly hosted by the Department of Physics of the University of Pisa and the Pisa branch of the Istituto Nazionale di Fisica Nucleare in July 2015. Previous hosts of the workshop include MIT in 1994, the University of Mainz in 1997, Jefferson Lab in 2000 and 2012, the University of Bonn in 2003, TUNL and Duke University in 2006, and the University of Bern in 2009. Hosting this workshop is an important and substantial service to the international low-energy QCD physics community. Nearly 120 participants attended the workshop, which delivered twenty plenary talks, and over ninety parallel presentations. Proceedings of the workshop are published in Proceedings of Science at https://pos.sissa.it/317/. These proceedings present topics convened in this 9 th workshop and provide a comprehensive review of the field, highlighting recent accomplishments and discussing challenges that will motivate research in the coming years.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

Description of induced nuclear fission with Skyrme energy functionals: Static potential energy surfaces and fission fragment properties

Eighty years after its experimental discovery, a description of induced nuclear fission based solely on the interactions between neutrons and protons and quantum many-body methods still poses formidable challenges. The goal of this paper is to contribute to the development of a predictive microscopic framework for the accurate calculation of static properties of fission fragments for hot fission and thermal or slow neutrons. To this end, we focus on the 239 Pu($n ,f$ ) reaction and employ nuclear density functional theory with Skyrme energy densities. Potential energy surfaces are computed at the Hartree-Fock-Bogoliubov approximation with up to five collective variables. We find that the triaxial degree of freedom plays an important role, both near the fission barrier and at scission. The impact of the parametrization of the Skyrme energy density and the role of pairing correlations on deformation properties from the ground state up to scission are also quantified. We introduce a general template for the quantitative description of fission fragment properties. It is based on the careful analysis of scission configurations, using both advanced topological methods and recently proposed quantum many-body techniques. We conclude that an accurate prediction of fission fragment properties at low incident neutron energies, although technologically demanding, should be within the reach of current nuclear density functional theory.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

Covariant Spectator Theory of np scattering: Deuteron magnetic moment and form factors

The deuteron magnetic moment is calculated using two model wave functions obtained from 2007 high precision fits to $np$ scattering data. Included in the calculation are a new class of isoscalar $np$ interaction currents which are automatically generated by the nuclear force model used in these fits. After normalizing the wave functions, nearly identical predictions are obtained: model WJC-1, with larger relativistic P-state components, gives 0.863(2), while model WJC-2 with very small $P$-state components gives 0.864(2) These are about 1\% larger than the measured value of the moment, 0.857 n.m., giving a new prediction for the size of the $\rho\pi\gamma$ exchange, and other purely transverse interaction currents that are largely unconstrained by the nuclear dynamics. The physical significance of these results is discussed, and general formulae for the deuteron form factors, expressed in terms of deuteron wave functions and a new class of interaction current wave functions, are given.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Single-shot in-line x-ray phase-contrast imaging of void-shockwave interactions in fusion energy materials

Recent breakthroughs in nuclear fusion, specifically the report of reactions exceeding scientific breakeven at the National Ignition Facility (NIF), highlight the potential of inertial fusion energy (IFE) as a sustainable and virtually limitless energy source. However, further progress in IFE requires characterization of defects in ablator materials and how they affect fuel capsule compression. Voids within the ablator can degrade energy yield, but their impact on the density distribution has primarily been studied through simulations, with limited high-resolution experimental validation. To address this, we used the x-ray free-electron laser (XFEL) at the matter in extreme conditions (MECs) instrument at the Linac coherent light source (LCLS) to capture 2D x-ray phase-contrast (XPC) images of a void-bearing sample with a composition similar to inertial confinement fusion (ICF) ablators. By driving a compressive shockwave through the sample using MEC's long-pulse laser system, we analyzed how voids influence shockwave propagation and density distribution during compression. To quantify this impact, we extracted phase information using two phase retrieval algorithms. First, we applied the contrast transfer function (CTF) method, paired with Tikhonov regularization and a fast optimization approach to generate an initial phase estimate. We then refined the result using a projected gradient descent (PGD) method that works directly with the sample's refractive index. Comparing these results with radiation adaptive grid Eulerian (xRAGE) radiation hydrodynamic simulations enables identification of model validation needs or improvements. By calculating phase maps in situ, it becomes possible to reconstruct areal density maps, improving understanding of laser-capsule interactions and advancing IFE research.

Hodge, D. S. [Colorado State Univ., Fort Collins, ↗
DOE OSTI2011

Measurement of low energy neutrino cross sections with the PEANUT experiment

The PEANUT experiment was designed to study neutrino interactions in the few GeV range using the NuMi beam at Fermilab. The detector uses a hybrid technique, being made of nuclear emulsions and scintillator trackers. Emulsion films act as a tracking device and they are interleaved with lead plates used as neutrino target. The detector is designed to reconstruct the topology of neutrino interactions at the single particle level. We present here the full reconstruction and analysis of a sample of 147 neutrino interactions occurred in the PEANUT detector and the measurement of the quasi-elastic, resonance and deep-inelastic contributions to the total charged current cross-section. This technique could be applied for the beam monitoring for future neutrino facilities.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Hidden Spin-Isospin Exchange Symmetry

The strong interactions among nucleons have an approximate spin-isospin exchange symmetry that arises from the properties of quantum chromodynamics in the limit of many colors, N c . However this large- N c symmetry is well hidden and reveals itself only when averaging over intrinsic spin orientations. Furthermore, the symmetry is obscured unless the momentum resolution scale is close to an optimal scale that we call Λ large-N c . We show that the large-N c derivation requires a momentum resolution scale of Λ large-N c ~ 500 MeV. We derive a set of spin-isospin exchange sum rules and discuss implications for the spectrum of 30 P and applications to nuclear forces, nuclear structure calculations, and three-nucleon interactions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Classical information driven quantum dot thermal machines

We analyze the transient response of quantum dot thermal machines that can be driven by hyperfine interaction acting as a source of classical information. Our setup comprises a quantum dot coupled to two contacts that drive heat flow while coupled to a nuclear spin bath. The quantum dot thermal machines operate both as batteries and as engines, depending on the parameter range. The electrons in the quantum dot interact with the nuclear spins via hyperfine spin-flip processes as typically seen in solid state systems such as GaAs quantum dots. The hyperfine interaction in such systems, which is often treated as a deterrent for quantum information processing, can favorably be regarded as a driving agent for classical information flow into a heat engine setup. We relate this information flow to Landauer’s erasure of the nuclear spin bath, leading to a battery operation. We further demonstrate that the setup can perform as a transient power source even under a voltage bias across the dot. Focusing on the transient thermoelectric operation, our analysis clearly indicates the role of Landauer’s erasure to deliver a higher output power than a conventional quantum dot thermoelectric setup and an efficiency greater than that of an identical Carnot cycle in steady state, which is consistent with recently proposed bounds on efficiency for systems subject to a feedback controller. The role of nuclear spin relaxation processes on these aspects is also studied. Finally, we introduce the Coulomb interaction in the dot and analyze the transient thermoelectric response of the system. Our results elaborate on the effective use of somewhat undesirable scattering processes as a non-equilibrium source of Shannon information flow in thermal machines and the possibilities that may arise from the use of a quantum information source.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Strange Mesons and Gluonic Excitations

In the standard model of particle physics, the interactions between the fundamental constituents of nuclear matter, quarks and gluons, are governed by the theory of Quantum Chromodynamics (QCD). A central goal of nuclear physics is to understand how hadrons, such as protons and neutrons, are formed from these underlying quark and gluon degrees of freedom. A hadron is primarily constructed from three quarks or a quark-antiquark pair; however, the theory of QCD allows for much more exotic configurations. One of the predicted exotic configurations is known as a hybrid meson, which contains an excited gluonic field in addition to the usual quark-antiquark pair. This project aims to search for and study these gluonic excitations using the Gluonic Excitation (GlueX) experiment at Jefferson Lab in Newport News, VA. The discovery potential of the experiment will be significantly extended by studying the quark flavor composition of the meson spectrum through the completion and use of an enhanced detector to identify mesons containing strange quarks. The unprecedented statistical precision of the data collected at GlueX will allow us to search for a pattern of light-quark hybrid mesons, providing new insight into the interactions that bind the fundamental quarks and gluons into the hadrons we observe in nature.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

In-medium Properties of {omega} and {eta}' Mesons in Elementary Reactions

We have investigated the in-medium properties of {omega} and eta prime mesons in photoproduction experiments using the Crystal Barrel(CB)/TAPS detector system at the ELSA accelerator facility in Bonn. Different methods to study the in-medium properties of the hadrons are discussed. The lineshape analysis of {omega}-mesons for two energy ranges shows limited sensitivity to in-medium modifications. Recent results on the in-medium width of the eta prime-meson, derived from transparency ratio measurements, are presented. The absorption of the eta prime-meson in nuclear matter is discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Theoretical highlights on neutrino-nucleus interactions: current challenges

The present theoretical status of neutrino interactions in the few-GeV region is reviewed. Quasielastic scattering, pion production and their importance for neutrino oscillation studies are discussed, making emphasis on the open questions that arise in the comparison with new experimental data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Sliding friction and wear behavior of nuclear graphite in high temperature inert environment: Influence of contact load, speed and temperature

Repeated dynamic interactions of graphitic components in pebble-bed gas-cooled nuclear reactors can cause abrasive wear-induced pebble surface damage, generate hazardous fine graphite debris, and alter fuel circulation dynamics due to changes in friction behavior. Comprehensive tribological characterization of nuclear graphitic materials in conditions relevant to reactor operation is needed to assess reactor long-term safety and performance. This work reports sliding friction and wear behavior of self-mated nuclear graphite ET-10 at various elevated temperatures (650 °C and 750 °C), sliding speeds (1 and 10 mm/s) and contact loads (20 and 40 N) in a controlled argon environment. The results revealed nonmonotonic frictional behavior with a higher running-in coefficient of friction (COF) followed by a lower steady-state COF, as a result of transition from two-body abrasion to three-body abrasion along with formation of a tribofilm. A key finding of this work is the sensitivity of the running-in COF to experimental conditions; maximum running-in values were lower at either elevated temperature (0.52–0.54) or reduced sliding speed (0.51–0.54). Conversely, the steady-state COF remained invariant at approximately 0.3 across all tested parameters. Transmission electron microscopy revealed a 0.5–2.0 μm thick nanocrystalline tribofilm that was thought to be formed by the compaction of the graphitic wear debris on the contact surface during the sliding process. The nanocrystalline nature of the tribofilm was further confirmed by Raman spectroscopy. As a result, the combination of tribological testing and morphological characterization provided a mechanistic understanding of the frictional behavior of nuclear graphite upon sliding.

Friction↗
DOE OSTI2015

Measurement of interaction between antiprotons

In this paper, one of the primary goals of nuclear physics is to understand the force between nucleons, which is a necessary step for understanding the structure of nuclei and how nuclei interact with each other. Rutherford discovered the atomic nucleus in 1911, and the large body of knowledge about the nuclear force that has since been acquired was derived from studies made on nucleons or nuclei. Although antinuclei up to antihelium-4 have been discovered and their masses measured, little is known directly about the nuclear force between antinucleons. Here, we study antiproton pair correlations among data collected by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC), where gold ions are collided with a centre-of-mass energy of 200 gigaelectronvolts per nucleon pair. Antiprotons are abundantly produced in such collisions, thus making it feasible to study details of the antiproton–antiproton interaction. By applying a technique similar to Hanbury Brown and Twiss intensity interferometry, we show that the force between two antiprotons is attractive. In addition, we report two key parameters that characterize the corresponding strong interaction: the scattering length and the effective range of the interaction. Our measured parameters are consistent within errors with the corresponding values for proton–proton interactions. Our results provide direct information on the interaction between two antiprotons, one of the simplest systems of antinucleons, and so are fundamental to understanding the structure of more-complex antinuclei and their properties.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Hop/STIP1 depletion alters nuclear structure via depletion of nuclear structural protein emerin

Highlights: • The link between the co-chaperone Hop/STIP1 and nuclear protein emerin is studied. • Hop overexpression or depletion targets emerin for degradation. • Hop and emerin interact in complexes that do not require Hsp90, but accommodate Hsp70. • Nuclear structure is altered in Hop and emerin depleted cells. Hop/STIP1 is a co-chaperone of Hsp70 and Hsp90 that regulates a number of cell biology processes via interactions with cellular proteins. Here we report a new relationship between Hop and the nuclear structural protein emerin in maintenance of nuclear morphology. Depletion or overexpression of Hop resulted in the reduction of emerin protein levels via proteasomal and lysosomal pathways. Co-immunoprecipitation assays confirmed that Hop and emerin are in a common complex, which could accommodate Hsp70 but not Hsp90, and that TPR2AB is required for the association. Loss of Hop or emerin led to a deformation of nuclear structure, a statistically significant decrease in nuclear size, and was associated with changes in the levels of nuclear proteins, lamin A-C and fibrillarin. The nuclear defects upon Hop loss could be rescued by emerin overexpression. Taken together, these data suggest that Hop stabilises emerin and that loss of Hop alters nuclear structure via emerin degradation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2011

Coordinated Research Projects of the IAEA Atomic and Molecular Data Unit

The IAEA Atomic and Molecular Data Unit is dedicated to the provision of databases for atomic, molecular and plasma-material interaction (AM/PMI) data that are relevant for nuclear fusion research. IAEA Coordinated Research Projects (CRPs) are the principal mechanism by which the Unit encourages data evaluation and the production of new data. Ongoing and planned CRPs on AM/PMI data are briefly described here.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2025

Affinity of LDR Organics to Cementitious Materials and Activated Carbon

The Hanford site stores approximately 56 million gallons of radioactive and hazardous waste in underground storage tanks. The current low-activity waste (LAW) vitrification facility does not have the capacity to immobilize all of the LAW. Therefore, cementitious waste forms are being evaluated as a cost-effective supplemental waste treatment, focusing on the solidification/immobilization of Land Disposal Restricted (LDR) organics, which is currently not recognized by the Environmental Protection Agency (EPA) as a standard treatment method (40 CFR 268.42). Previous efforts by the EPA and waste management agencies have highlighted the potential for cementitious materials to retain certain organic species through physical (encapsulation) and chemical (sorption) interactions.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Microscale Thermophoresis (MST) as a Tool to Study Binding Interactions of Oxygen-Sensitive Biohybrids

Microscale thermophoresis (MST) is a technique used to measure the strength of molecular interactions. MST is a thermophoretic-based technique that monitors the change in fluorescence associated with the movement of fluorescent-labeled molecules in response to a temperature gradient triggered by an IR LASER. MST has advantages over other approaches for examining molecular interactions, such as isothermal titration calorimetry, nuclear magnetic resonance, biolayer interferometry, and surface plasmon resonance, requiring a small sample size that does not need to be immobilized and a high-sensitivity fluorescence detection. In addition, since the approach involves the loading of samples into capillaries that can be easily sealed, it can be adapted to analyze oxygen-sensitive samples. In this Bio-protocol, we describe the troubleshooting and optimization we have done to enable the use of MST to examine protein–protein interactions, protein–ligand interactions, and protein–nanocrystal interactions. The salient elements in the developed procedures include 1) loading and sealing capabilities in an anaerobic chamber for analysis using a NanoTemper MST located on the benchtop in air, 2) identification of the optimal reducing agents compatible with data acquisition with effective protection against trace oxygen, and 3) the optimization of data acquisition and analysis procedures. The procedures lay the groundwork to define the determinants of molecular interactions in these technically demanding systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

On the theory of double quantum NMR in polymer systems: The second cumulant approximation for many spin I = 1/2 systems

General analytical expressions for Double Quantum Nuclear Magnetic Resonance (DQ NMR) kinetic curves of many-spin I = 1/2 systems are derived with an accuracy of the second cumulant approximation. The expressions obtained exactly describe the initial part of the kinetic curves and provide a reasonable approximation up to times of about the effective spin-relaxation time. For the case when the system contains two isolated spins, this result exactly reproduces known expressions. In the case of polymer melts, the intermolecular magnetic dipole-dipole interactions significantly influence the time dependence of the DQ NMR kinetic curves.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Implementing Chiral Three-Body Forces in Terms of Medium-Dependent Two-Body Forces

Three-nucleon (3N) forces are an indispensable ingredient for accurate few-body and many- body nuclear structure and reaction theory calculations. While the direct implementation of chiral 3N forces can be technically very challenging, a simpler approach is given by employing instead a medium-dependent NN interaction V med that reflects the physics of three-body forces at the two-body normal-ordered approximation. We review the derivation and construction of Vmed from the chiral 3N interaction at next-to-next-to-leading order (N2LO), consisting of a long-range 2π-exchange term, a mid-range 1π-exchange component and a short-range contact-term. Several applications of V med to the equation of state of cold nuclear and neutron matter, the nucleon single-particle potential in nuclear matter, and the nuclear quasiparticle interaction are discussed. We also explore differences in using local vs. nonlocal regulating functions on 3N forces and make direct comparisons to exact results at low order in perturbation theory expansions for the equation of state and single-particle potential. We end with a discussion and numerical calculation of the in-medium NN potential V med from the next-to-next-to-next-to-leading order (N3LO) chiral 3N force, which consists of a series of long-range and short-range terms.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗