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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

A Measurement of the Neutron Electromagnetic Form Factor Ratio from a Rosenbluth Technique with Simultaneous Detection of Neutrons and Protons

The internal structure of protons and neutrons provides insight into both the dynamical behavior of the constitute quarks and gluons, and emergent properties of the nucleons (such as mass, spin, and electromagnetic distributions). Elastic electron-nucleon scattering can probe the elastic electromagnetic form factors of the nucleon. The electric and magnetic form factors, respectively, encode information about the internal charge and magnetization distributions within the nucleon. Precision data for these form factors, over a broad range of the four-momentum transfer squared, Q^2, can benchmark theoretical models describing the strong interaction of nuclear physics. The Super BigBite Spectrometer (SBS) program in Hall A at Jefferson Lab, is a series of high-precision experiments which seek to significantly extend the Q^2 reach of previous data for the nucleon electromagnetic form factors. The first two experiments of this program are known as G_M^n and the neutron Two Photon Exchange (nTPE) and the data were collected from October 2021 to February 2022. Both experiments were conducted with the simultaneous measurement of D(e,e'n) and D(e,e'p) reactions for quasi-elastic electron-deuteron scattering. The scattered electrons were detected in the BigBite Spectrometer, which features multiple large-acceptance Gas Electron Multiplier (GEM) detectors. The Super BigBite Spectrometer provided simultaneous detection of scattered nucleons, and utilized a large acceptance dipole magnet and Hadron Calorimeter (HCal). The G_M^n experiment provides precision measurements of the neutron magnetic form factor, via the ratio method, over a Q^2 range of 3.0 to 13.5 (GeV/c)2. From this data analysis, preliminary values for G_M^n/µ_n G_D are extracted. For Q^2=4.48 (GeV/c)2 we find G_M^n/µ_n G_D=0.9546±0.0132 and for Q^2=4.476 (GeV/c)2 we find G_M^n/µ_n G_D=0.9563±0.0110. These preliminary G_M^n/µ_n G_D values are more precise than existing world data in this Q^2 regime and are consistent with the most recent parameterization of the G_M^n/µ_n G_D world data. The nTPE experiment provides a first measurement of the neutron Rosenbluth Slope and seeks to quantify the two-photon exchange(TPE) contribution to elastic electron-neutron scattering at a fixed Q^2=4.5 (GeV/c)2 with two different beam energies and scattering angle values. For data of the proton form factor ratio, µ_p G_E^p/G_M^p, significant discrepancies exist between values obtained from Rosenbluth Separation and polarization transfer measurement, particularly at large Q^2, and TPE contributions are thought to resolve this discrepancy. The impacts of TPE contributions have not yet been experimentally established for the neutron. From the data analysis presented in this dissertation, a preliminary result for the neutron Rosenbluth Slope is found as S^n=(G_E^n )^2/t_n (G_M^n )^2=0.0916±0.0476 for Q^2=4.48 (GeV/c)2. This value of the neutron Rosenbluth Slope is consistent with the world data extrapolation and the absence of large TPE corrections.

Wertz, Ezekiel [Thomas Jefferson National Accelera↗
NASA NTRS1995

Proton affinity determinations and proton-bound dimer structure indications in C2 to C15, (alpha),(omega)-alkyldiamines

The 'kinetic method' was used to determine the proton affinity (PA) of a,coalkyldiamines from collision induced dissociation (CID) studies of protonated heterodimers. These PA values were consistently lower than those reported in the proton affinity scale. The apparent discrepancy was rationalized in terms of differences in the conformation of the protonated diamine monomers. The minimum energy species, formed by equilibrium proton transfer processes, have a cyclic conformation and the ion charge is shared by both amino-groups which are bridged by the proton. On the other hand, the species formed through dissociation of protonated dimers have a linear structure and the charge is localized on one of the amino-groups. Thus, the difference in the PA values obtained by both methods is a measure of the additional stability acquired by the protonated diamines through cyclization and charge delocalization. The major collision dissociation pathway of the protonated diamine monomers involved elimination of an ammonia moiety. Other reactions observed included loss of the second amino-group and several other bond cleavages. CID of the protonated dimers involved primarily formation of a protonated monomer through cleavage of the weaker hydrogen bond and subsequently loss of ammonia at higher collision energies. As observed from the CID studies, doubly charged ions were also formed from the diamines under conditions of the electrospray ionization.

Karpas, Z.↗
DOE OSTI2024

Exploring the impact of high-precision top-quark pair production data on the structure of the proton at the LHC

The impact of recent LHC top-quark pair production single differential cross section measurements at 13 TeV collision energy on the structure of the proton is explored. In particular, the impact of these high-precision data on the gluon and other parton distribution functions (PDFs) of the proton at intermediate and large partonic momentum fraction x is analyzed. This study extends the CT18 global analysis framework to include these new data. The interplay between top-quark pair and inclusive jet production as well as other processes at the LHC, is studied. In addition, a study of the impact of scale choice on the theory description of the new 13 TeV t t ¯ measurements is performed. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2022

A Strong-QCD Regime Measurement of the Proton’s Spin Structure

The theory of the strong force, Quantum Chromodynamics (QCD) remains one of the most important ways to understand the fundamental properties of ordinary matter. However, at low momentum transfer Q 2 , in the regime where the strong force becomes extremely strong, our understanding of QCD for ordinary nucleons becomes hazy. Several cutting edge theories such as Chiral Perturbation Theory (χPT) and Lattice QCD have provided valuable predictions in this regime, but Lattice QCD has not yet extended predictions of many important quantities to this kinematic region, and Chiral Perturbation Theory has faced several important disagreements with experimental data for the neutron over the last several decades. It is therefore of extreme importance to have a benchmark of experimental data in the low energy regime for the proton’s behavior, as a test of leading theories for the behavior of QCD in this regime. The E08-027 (g2p) experiment ran at Jefferson Lab in 2012 with the goal of collecting this valuable data, and though I was still completing my undergraduate studies at the time, I became involved in the analysis in 2015 and built on the previous work to complete it and analyze the exciting results. This experiment achieved a high precision measurement of the spin structure functions g1 and g2 for the proton, quantities which describe the internal spin structure of the proton. These measurements were taken in the valuable low Q 2 region described above, and used to extract several moments of these spin structure functions which can be directly compared to the cutting-edge predictions of Chiral Perturbation Theory. Though the experiment’s timeline was such that I didn’t have a chance to work directly on the experimental setup, I had the opportunity to acquire hands-on experience working on a polarized target at UNH which is very similar to the crucial polarized target used in the g2p experiment. Full details of the g2p experiment and my experimental work at the University of New Hampshire are presented in this thesis, as well as a detailed description of the analysis process and the exciting benchmark results, which serve as a direct test of all current and future theories of QCD in the low-Q 2 regime.

Ruth, David↗
DOE OSTI2021

Neutron Structure Functions at Large Bjorken X

The E12-10-002 (F2) experiment ran in Hall C at JLab to extract the F2 structure functions of proton and neutron from inclusive H(e, e0) and D(e, e0) reactions in the high Bjorken x region. Those extractions put constraints on the Parton Distribution Functions PDFs (especially at large Bjorken x), and facilitate the study of Quark Hadron Duality. The F2 experiment measurements covers a large kinematic range in x from 0.2 to 1.0, and in Q2 from 4 to 16 GeV2 . While the proton F2 structure function has been studied extensively through inelastic electron-proton scattering, much less is known about neutron structure due to the unavailability of high density, free neutron targets. The BONuS12 experiment was proposed to measure the neutron F2 on a nearly free neutron within a weakly bound deuteron target via the spectator tagging method. Tagging the slow backward moving spectator protons minimizes both off-shell and final-state interaction effects, and the measured proton momentum is used to correct for the initial-state momentum of the struck neutron. The recoil detector is used to detect spectator protons with momenta 70 < ps < 150 MeV/c. This dissertation outlines the design, construction and testing of the recoil detector, Radial Time Projection Chamber (RTPC) and discusses the results of the H(e, e0) and D(e, e0) cross sections and the F2 structure functions obtained from the Hall C F2 data analysis.

Nadeeshani, Sooriyaarachchilage↗
NASA NTRS2003

Structure-Derived Proton-Transfer Mechanism of Action Human Pyruvate Dehydrogenase

The derivative of vitamin B1 thiamin pyrophosphate (TPP) is a cofactor of pyruvate dehydrogenase (E1p) that is involved in decarboxylation of pyruvate followed by reductive acetylation of lipoic acid covalently bound to a lysine residue of dihydrolipoamide acetyltransferase. The structure of E1p recently determined in our laboratory revealed patterns of association of foul subunits and specifics of two TPP binding sites. The mechanism of action in part includes a conserved hydrogen bond between the N1' atom of the aminopyrimidine ring of the cofactor and the carboxylate group of Glu59 from the beta subunits, and a V-conformation of the cofactor that brings the N4' atom of the aminopyrimidine ring to the distance of the intramolecular hydrogen bond formed with the C2-atom of the thiazolium moiety. The carboxylate group of Glu59 is the local proton acceptor that enables proton translocation within the aminopyrimidine ring and stabilization of the rare N4' - iminopyrimidine tautomer. Based on the analysis of E1p structure, we postulate that the protein environment drives N4' - amino/N4' - imino dynamics resulting in a concerted shuttle-like movement of the subunits. We also propose that this movement of the subunits is strictly coordinated with the two enzymatic reactions carried out in E1p by each of the two cofactor sites. It is proposed that these reactions are in alternating phases such that when one active site is involved in decarboxylation, the other is involved in acetylation of lipoyl noiety.

Ciszak, Ewa↗
DOE OSTI2024

Up and down quark structure of the proton

We report an improved measurement of the valence u and d quark distributions from the forward-backward asymmetry in the Drell-Yan process using 8.6 fb − 1 of data collected with the D0 detector in p p ¯ collisions at s = 1.96 . This analysis provides the values of new structure parameters that are directly related to the valence up and down quark distributions in the proton. In other experimental results measuring the quark content of the proton, d quark contributions are mixed with those from other quark flavors. In this measurement, the u and d quark contributions are separately extracted by applying a factorization of the QCD and electroweak portions of the forward-backward asymmetry. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Characterisation of the dip-bump structure observed in proton–proton elastic scattering at $\sqrt{s}$ = 8 TeV

The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton–proton scattering at √s = 8TeV in the squared four-momentum transfer range 0.2GeV 2 < |t| < 1.9GeV 2 . This interval includes the structure with a diffractive minimum (“dip”) and a secondary maximum (“bump”) that has also been observed at all other LHC energies, where measurements were made. A detailed characterisation of this structure for √s = 8 TeV yields the positions, |t| dip = (0.521 ± 0.007)GeV 2 and |t| bump = (0.695 ± 0.026)GeV 2 , as well as the cross-section values, dσ/dt| dip = (15.1 ± 2.5)μb/GeV 2 and dσ/dt| bump = (29.7 ± 1.8)μb/GeV 2 , for the dip and the bump, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1974

Temperature and density structure of thermal proton flows

Thermal proton flows along magnetic field lines are an important feature of magnetosphere-ionosphere coupling. In this paper we report the results of a theoretical study of the thermal structure of such flows. The adopted steady state model is based upon O+, H+, and electrons with self-consistent solutions for the separate O+, H+, and electron temperatures, the O+ and H+ densities and the H+ drift velocity. Through investigation of a number of parameters affecting the model, it is shown that Joule heating arising from the flow of H+ through O+ preferentially heats H+, so that the H+ temperature is substantially greater than the O+ temperature. Low O+ densities characteristic of the trough region appear to give high H+/O+ temperature ratios. Typical O+ densities characteristic of polar wind flow regions give moderate H+/O3 temperature ratios. The Mach number of H+ outflow is substantially reduced in the present models in comparison with the older fixed temperature calculations.

Banks, P. M.↗
DOE OSTI2025

The Three-Dimensional Structure of the Proton

This project addresses three key questions about the “glue that binds us all” (Nuclear Science Advisory Council’s Long-Range Plan). First, what is the three-dimensional momentum distribution of gluons within the nucleon? Second, how is the motion of quarks and gluons correlated within hadrons and how do those correlations manifest in nucleon structure? Third, how can lattice calculations guide the experimental study of hadron structure at the future electron-ion collider (EIC)?

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Tailoring the structural durability and proton conductivity of electrolytes for highly fuel-flexible and reversible ceramic cells

A durable and high ionic conducting electrolyte is critical for achieving fuel-flexible and reversible protonic ceramic cells (PCCs) at reduced temperatures since the developed electrolyte materials are vulnerable to steam, CO 2 , or coking deterioration. Here, we report a fast-conducting electrolyte material BaZr 0.06 Ce 0.7 Y 0.06 Yb 0.06 Hf 0.06 Gd 0.06 O 3−δ (BZCYYbHG), demonstrating excellent durability against CO 2 and H 2 O under the realistic electrolysis operations, and a high conductivity of 0.017 S cm −1 at 550 °C for lowering the PCC operating temperature. Further, density functional theory calculations indicate that the higher configurational entropy of mixing at the B-site cations slightly reduces the hydrogen adsorption energy, suggesting a higher incorporation rate of protons or hydrogen atoms into the electrolyte bulk. Ultimately, single cells with the BZCYYbHG electrolyte deliver peak power densities of 1.39, 1.12, and 0.7 W cm −2 in H 2 , NH 3 , and wet CH 4 at 550 °C with promising durability. In addition, the PCCs achieve a current density of −1.61 A cm −2 at 1.3 V and 550 °C with a high faradaic efficiency of 91.3% at −0.5 A cm −2 , enabling stable operations in steam electrolysis mode under humid air (30% H 2 O), wet air containing CO 2 (up to 10%), and reversible cycling.

25 ENERGY STORAGE↗
DOE OSTI2025

Spin structure of the proton from global QCD analysis

In this talk we review recent results for spin-dependent parton distribution functions extracted in global QCD analysis of high energy scattering data by the JAM collaboration, including inclusive and semi-inclusive deep-inelastic scattering, jet and weak boson production in polarised hadron-hadron collisions. In particular, we focus on the determination of the gluon polarisation in the proton, whose sign and magnitude have been the subject of debate recently.

Melnitchouk, Wally [Thomas Jefferson National Acce↗
DOE OSTI2022

Fine structure in the odd-odd proton emitter Tm 144

Axial symmetry breaking in 144 Tm is probed by examining its proton emission fine structure. The ground-state spin and parity in 144 Tm and daughter 143 Er are assigned unambiguously based on the corroboration of our calculations with the present data. Here we establish the first microscopic description of fine structure in odd-odd proton emitters, which is capable of resolving ambiguities present in the assignments of transitions in such nuclei.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Extraction of Proton and Deuteron F2 Structure Function from Inclusive Electron-Nucleon Scattering at Large Bjorken-X

The E12-10-002 experiment measured the inclusive electron-nucleon cross section at Jeferson Lab at large Q2 (up to 16 GeV2) and a large range of x (up to 0.99). The data is analyzed and the cross sections are extracted for hydrogen and deuterium. Then the F2 structure function is extracted for hydrogen and deuterium. Finally the quark-hadron duality is tested for the proton F2 structure function for the previous world data and this experiment.

Biswas, Debaditya↗