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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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NASA NTRS1977

A model of the near-earth plasma environment and application to the ISEE-A and -B orbit

A model of the near-earth environment to obtain a best estimate of the average flux of protons and electrons in the energy range from 0.1 to 100 keV for the International Sun-Earth Explorer (ISEE)-A and -B spacecraft. The possible radiation damage to the thermal coating on these spinning spacecraft is also studied. Applications of the model to other high-altitude satellites can be obtained with the appropriate orbit averaging. This study is the first attempt to synthesize an overall quantitative environment of low-energy particles for high altitude spacecraft, using data from in situ measurements.

Chan, K. W.↗

DOE OSTI2022

Two-proton decay from α-cluster states in 10 C and 11 N

Two-proton decay from excited states in 10 C and 11 N has been characterized from an analysis of the 2p + 2α and 3p + 2α exit channels. Data from four previously published invariant-mass studies associated with inelastic excitation, multinucleon knockout, and neutron pickup reactions have been considered. A rotational band in 10 C was identified built on the second 0 + state which has strong α-cluster molecular structure. The members of this band were tentatively identified up to J π = 4 + and all identified states have a prompt 2p decay branch. The spins of the 0 + and 2 + members were deduced from comparisons of the momentum correlations in their 2p branches to those from known 2p emitters. The 2 + and the tentative 4 + members are both above the α threshold and exhibit large reduced decay widths for α emission. This band exhibits a similar moment of inertia to its analog in the mirror nucleus 10 Be. Evidence is also presented for a molecular band in 11 N built on the second 3/2 – state which 2p decays. Furthermore, tentative members of this band have been assigned up to J π = 9/2 – and their excitation energies also match their likely analogs in the mirror nucleus 11 Be.

6 ≤ A ≤ 19↗

DOE OSTI2022

Hadron Polarimetry for the Electron-Ion Collider

The Electron-Ion Collider (EIC) will be the first collider to use both polarized electron beams and polarized proton and light ion beams. It will therefore offer unique opportunities to study the structure of nucleons and to answer fundamental questions in QCD. The uncertainties on the polarization measurement translate directly into the uncertainties of final physics observables. Hence, a precise measurement of the hadron beam polarization and a good control of systematic uncertainties are critical for the success of the spin program at the EIC. Contrary to the case of electron beam polarimetry, which uses physical processes derived from first principles that allow a high precision extraction of the electron beam polarization, for hadron beams no such process is available. The currently best used methods rely on the process of elastic scattering in the Coulomb-Nuclear Interference (CNI) region, for which there are only effective models available. The experience from RHIC, the only existing polarized proton collider, will be detailed and the challenges of the measurements at the EIC will be addressed. In particular, measurements of the present RHIC polarimeters and simulations of the future EIC polarimeters will be presented.

Nunes, Ana Sofia↗

DOE OSTI2021

Photoproduction of the b 1 (1235) Meson off the proton at E gamma = 6-12 GeV

The GlueX Experiment at Jefferson Lab directs a linearly polarized photon beam on a liquid hydrogen target surrounded by an almost hermetic detector. The experiment aims to study the meson spectrum in the light-quark sector and search for exotic spin-parity states predicted by lattice QCD calculations. The lightest exotic candidate is the π 1 meson, which is predicted to decay dominantly to b 1 π. In this thesis, we present efforts to characterize the ωπ 0 decay channel of the b 1 meson as precursor to an analysis of the sought-after π 1 exotic state. We present an introduction to the physics involved and an overview of the detector subsystems with a focus on the Barrel Calorimeter gain monitoring system, as part of the service work expected by the GlueX Collaboration. We discuss the data analysis method used and present two frameworks, for angular moments and partial waves analyses. Details of the simulation used to calculate the detector acceptance. A proof of concept partial wave analysis is presented along with experimental angular moments as first step to a full analysis of the angular distribution Our partial wave analysis indicates that both S- and D-waves are needed, in qualitative agreement with theoretical expectations. The cross-section of the omega π 0 channel is extracted to be of the scale of 1 μb in agreement with previous measurements. The differential cross-section indicates the presence of two production processes with p 1 = -5:24 ± 0:04 for 0:25 < -t < 0:95 GeV 2 ~c 2 and p 2 = -1:24 ± 0:05 for 0:95 < -t < 2:0 GeV 2 ~c 2 , which does not agree with results from previous experiments. The s-channel helicity conservation and helicity amplitudes of the b 1 meson are presented as additional experimental observables. Our results confirm that the b1 photoproduction process does not conserve s-channel helicity though they do not align with previous measurements. The helicity amplitude of the omega are extracted to be |F 1 | 2 = 0:3037 ± 0:0003 which does not agree with the expected value of a b 1 decay or results from a previous experiment. Future steps in all these analyses will be continued by a new graduate student in the group, culminating in a publication.

Foda, Ahmed↗

NASA NTRS1994

Application of electron paramagnetic resonance imaging to the characterization of the Ultem(R) exposed to 1 MeV electrons. Correlation of radical density data to tiger code calculations

A major long-term goal of the Materials Division at the NASA Langley Research Center is the characterization of new high-performance materials that have potential applications in the aircraft industry, and in space. The materials used for space applications are often subjected to a harsh and potentially damaging radiation environment. The present study constitutes the application of a novel technique to obtain reliable data for ascertaining the molecular basis for the resilience and durability of materials that have been exposed to simulated space radiations. The radiations of greatest concern are energetic electrons and protons, as well as galactic cosmic rays. Presently, the effects of such radiation on matter are not understood in their entirety. It is clear however, that electron radiation causes ionization and homolytic bond rupture, resulting in the formation of paramagnetic spin centers in the polymer matrices of the structural materials. Since the detection and structure elucidation of paramagnetic species are most readily accomplished using Electron Paramagnetic Resonance (EPR) Spectroscopy, the NASA LaRC EPR system was brought back on-line during the 1991 ASEE term. The subsequent 1992 ASEE term was devoted to the adaptation of the EPR core system to meet the requirements for EPR Imaging (EPRI), which provides detailed information on the spatial distribution of paramagnetic species in bulk media. The present (1994) ASEE term was devoted to the calibration of this EPR Imaging system, as well as to the application of this technology to study the effects of electron irradiation on Ultem(exp R), a high performance polymer which is a candidate for applications in aerospace. The Ultem was exposed to a dose of 2.4 x 10(exp 9) Rads (1-MeV energy/electron) at the LaRC electron accelerator facility. Subsequently, the exposed specimens were stored in liquid nitrogen, until immediately prior to analyses by EPRI. The intensity and dimensions of the EPR Images that were generated for the irradiated specimens showed that the electrons penetrated the material to a depth of approximately 0.125 inch. These data show a very high degree of correlation to the energy deposition profile as predicted by the Tiger Code, a Monte Carlo code that provides guidelines for the transport of electrons in matter. Subsequent efforts will focus on delineating the transport properties of energetic protons in Ultem(R).

Suleman, Naushadalli K.↗

DOE OSTI2023

Search for high-mass $Wγ$ and $Zγ$ resonances using hadronic $W/Z$ boson decays from 139 fb –1 of $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

A search for high-mass charged and neutral bosons decaying to $Wγ$ and $Zγ$ final states is presented in this paper. The analysis uses a data sample of $\sqrt{s}$ = 13 TeV proton-proton collisions with an integrated luminosity of 139 fb –1 collected by the ATLAS detector during LHC Run 2 operation. The sensitivity of the search is determined using models of the production and decay of spin-1 charged bosons and spin-0/2 neutral bosons. The range of resonance masses explored extends from 1.0 TeV to 6.8 TeV. At these high resonance masses, it is beneficial to target the hadronic decays of the $W$ and $Z$ bosons because of their large branching fractions. The decay products of the high-momentum $W/Z$ bosons are strongly collimated and boosted-boson tagging techniques are employed to improve the sensitivity. No evidence of a signal above the Standard Model backgrounds is observed, and upper limits on the production cross-sections of these bosons times their branching fractions to $Wγ$ and $Zγ$ are derived for various boson production models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2022

Study of the doubly charmed tetraquark $\mathrm{T}$ $^+_{cc}$

Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the D 0 D 0 π + mass spectrum just below the D *+ D 0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalar T$^{+}_{cc}$ tetraquark with a quark content of cc$\bar{u}\bar{d}$ and spin-parity quantum numbers J P = 1 + . Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D *+ mesons is consistent with the observed D 0 π+ mass distribution. To analyse the mass of the resonance and its coupling to the D*D system, a dedicated model is developed under the assumption of an isoscalar axial-vector T$^{+}_{cc}$ state decaying to the D*D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the T$^{+}_{cc}$ state. In addition, an unexpected dependence of the production rate on track multiplicity is observed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2025

Investigation of 31 P levels near the proton threshold with nuclear resonance fluorescence and the impact on the 30 Si (𝑝,𝛾)⁢ 31 P thermonuclear rate

We investigated the nuclear structure of 31 P near the proton threshold using nuclear resonance fluorescence (NRF) to refine the properties of key resonances in the 30 Si (𝑝,𝛾)⁢ 31 P reaction, which is critical for nucleosynthesis in stellar environments. Excitation energies and spin-parities were determined for several states, including two unobserved resonances at 𝐸 𝑟 = 18.7keV and 𝐸 𝑟 = 50.5keV. The angular correlation analysis enabled the first unambiguous determination of the orbital angular momentum transfer for these states. These results provide a significant update to the 30 Si (𝑝,𝛾)⁢ 31 P thermonuclear reaction rate, with direct implications for models of nucleosynthesis in globular clusters and other astrophysical sites. The revised rate is substantially lower than previous estimates at temperatures below 200 MK, affecting predictions for silicon isotopic abundances in stellar environments. Furthermore, our work demonstrates the power of NRF in constraining nuclear properties, and provides a framework for future studies of low-energy resonances relevant to astrophysical reaction rates.

20 ≤ A ≤ 38↗

DOE OSTI2025

Photoproduction of two charged pions off protons in the resonance region

Photoproduction of charged pions pairs off protons is studied within the invariant masses of the final state hadrons from 1.6 to 2.4 GeV at the Thomas Jefferson National Accelerator Facility with the CLAS detector. The total and differential cross sections and spin-density matrix elements are presented for the isobars pρ 0 (770), Δ(1232) ++ π − , and Δ(1232) 0 π + . The data are included in the Bonn-Gatchina coupled-channel analysis and provide the information necessary to determine the branching fractions of Nρ(770) decays for most known N* and Δ* resonances. For the first time, the Nρ branching ratios are obtained here from an event-based likelihood to γp → π + π − p.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

NASA NTRS1984

Activities of the Solid State Physics Research Institute

Three research programs are reviewed. These programs are muon spin rotation, studies of annealing in gallium arsenide and Hall effect studies in semiconductors. The muon spin rotation work centers around the development of a facility at the Alternating Gradient Synchrotron of BNL. Studies of annealing in GaAs concerns itself with the measurement of depolarization in GaAs. The Hall effect studies of proton damaged semiconductors provide new information on the nature of defects and dislocations in GaAs.

Source record↗

DOE OSTI2022

In-beam γ-ray spectroscopy of 32 Mg via direct reactions

Background: The nucleus 32 Mg (N=20 and Z=12) plays a central role in the so-called “island of inversion,” where in the ground states sd-shell neutrons are promoted to the fp-shell orbitals across the shell gap, resulting in the disappearance of the canonical neutron magic number N=20. Purpose: The primary goals of this work are to extend the level scheme of 32Mg, provide spin-parity assignments to excited states, and discuss the microscopic structure of each state through comparisons with theoretical calculations. Method: In-beam γ-ray spectroscopy of 32 Mg was performed using two direct-reaction probes: one-neutron (two-proton) knockout reactions on 33 Mg ( 34 Si). Final-state exclusive cross sections and parallel momentum distributions were extracted from the experimental data and compared with eikonal-based reaction model calculations combined with shell-model overlap functions. Results: Owing to the remarkable selectivity of the one-neutron and two-proton knockout reactions, a significantly updated level scheme for 32 Mg, which exhibits negative-parity intruder and positive-parity normal states, was constructed. The experimental results were confronted with four different nuclear structure models. Conclusions: In some of these models, different aspects of 32 Mg and the transition into the island of inversion are well described. However, unexplained discrepancies remain, and, even with the help of these state-of-the-art theoretical approaches, the structure of this key nucleus is not yet fully captured.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2026

Observation of a cross-section enhancement near the production threshold in $\sqrt{s} = 13$ TeV pp collisions with the ATLAS detector

A measurement of $t\bar{t}$ production is presented in the invariant-mass region near the pair production threshold, $m_{t\bar{t}} \sim 345$ GeV, in final states with two charged leptons and multiple jets. The measurement is based on $140\,\mathrm{fb}^{-1}$ of proton–proton collision data collected at $\sqrt{s} = 13$ TeV with the ATLAS detector at the Large Hadron Collider. The data are compared to two models of $t\bar{t}$ production: a baseline model including only perturbative quantum chromodynamics (pQCD) predictions for the hard process at approximate next-to-next-to leading order accuracy in the strong coupling, and an extended model that, in addition, incorporates non-relativistic QCD simulations that also include the formation of colour-singlet quasi-bound-states near the $t\bar{t}$ threshold. The agreement between the data and the models is quantified via a profile-likelihood fit to the reconstructed $m_{t\bar{t}}$ distributions, in bins of two angular observables sensitive to spin-correlations in the $t\bar{t}$ system. An excess of events is observed over the baseline pQCD prediction, with an observed significance over 8 standard deviations. This excess is consistent with the formation of colour-singlet and spin-singlet S-wave quasi-bound $t\bar{t}$ states, as predicted by non-relativistic QCD, and corresponds to an observed cross-section of $9.3^{+1.4}_{-1.3}$ pb.

Large Hadron Collider↗

DOE OSTI2024

Accessing the gluon GTMD F 1 , 4 in exclusive π 0 production in e p collisions

We demonstrate that the longitudinal single target-spin asymmetry in exclusive π 0 production in e p collisions can give access to the imaginary part of the gluon generalized transverse momentum distribution (GTMD) F 1 , 4 . Such a longitudinal spin asymmetry that results from the Coulomb-nuclear interference effect, leads to a characteristic azimuthal angular correlation of sin 2 ϕ , where ϕ is the azimuthal angle between the scattered lepton transverse momentum and the recoil proton’s transverse momentum. We also present a numerical estimate of the asymmetry for the kinematics accessible at EIC and EicC. Published by the American Physical Society 2024

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2023

Search for Weak Side Branches in the Electromagnetic Decay Paths of the 6526-keV 10 + Isomer in 54 Fe

High-spin nuclear isomers in $N≈Z$ nuclei between doubly magic 40 Ca and 56 Ni provide an excellent testing ground for the nuclear shell model and questions related to isospin symmetry breaking in the vicinity of the proton drip line. The purpose of the present study is to investigate the possibility of weak electromagnetic decay branches along the decay paths of the 6526-keV 10 + isomer in 54 Fe. The isomer was strongly populated by means of the fusion-evaporation reaction 24 Mg( 36 Ar,$α$2$p$) 54$m$ Fe. The Gammasphere array was used to detect $γ$-ray cascades emitted from the isomeric state. By means of $γγγ$ coincidences, weak non-yrast decay branches can be discriminated, with the isomer’s half-life confirmed at $T$ 1/2 = 363 (4) ns. The yrast ${6}_{1}^{+}$ → ${2}_{1}^{+}$ $E4$ cross-over transition was interrogated. The observations are compared with shell-model calculations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

NASA NTRS1989

Electron Spin Resonance (ESR) studies of returned comet nucleus samples

The most important objective of the Comet Nucleus Sample Returm Mission is to return samples which could reflect formation conditions and evolutionary processes in the early solar nebula. It is expected that the returned samples will consist of fine-grained silicate materials mixed with ices composed of simple molecules such as H2O, NH3, CH4 as well as organics and/or more complex compounds. Because of the exposure to ionizing radiation from cosmic-ray, gamma-ray, and solar wind protons at low temperature, free radicals are expected to be formed and trapped in the solid ice matrices. The kind of trapped radical species together with their concentration and thermal stability can be used as a dosimeter as well as a geothermometer to determine thermal and radiation histories as well as outgassing and other possible alternation effects since the nucleus material was formed. Since free radicals that are known to contain unpaired electrons are all paramagnetic in nature, they can be readily detected and characterized in their native form by the Electron Spin Resonance (ESR) method. In fact, ESR has been shown to be a non-destructive, highly sensitive tool for the detection and characterization of paramagnetic, ferromagnetic, and radiation damage centers in terrestrial and extraterrestrial geological samples. The potential use of ESR as an effective method in the study of returned comet nucleus samples, in particular, in the analysis of fine-grained solid state icy samples is discussed.

Tsay, Fun-Dow↗

DOE OSTI2020

Enhancement‐Mode PEDOT:PSS Organic Electrochemical Transistors Using Molecular De‐Doping

Abstract Organic electrochemical transistors (OECTs) show great promise for flexible, low‐cost, and low‐voltage sensors for aqueous solutions. The majority of OECT devices are made using the polymer blend poly(ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), in which PEDOT is intrinsically doped due to inclusion of PSS. Because of this intrinsic doping, PEDOT:PSS OECTs generally operate in depletion mode, which results in a higher power consumption and limits stability. Here, a straightforward method to de‐dope PEDOT:PSS using commercially available amine‐based molecular de‐dopants to achieve stable enhancement‐mode OECTs is presented. The enhancement‐mode OECTs show mobilities near that of pristine PEDOT:PSS (≈2 cm 2 V −1 s −1 ) with stable operation over 1000 on/off cycles. The electron and proton exchange among PEDOT, PSS, and the molecular de‐dopants are characterized to reveal the underlying chemical mechanism of the threshold voltage shift to negative voltages. Finally, the effect of the de‐doping on the microstructure of the spin‐cast PEDOT:PSS films is investigated.

Keene, Scott T.↗

DOE OSTI2023

Polarized fusion and potential in situ tests of fuel polarization survival in a tokamak plasma

Abstract The use of spin-polarized fusion fuels would provide a significant boost towards the ignition of a burning plasma. The cross section for D + T → α + n, would be increased by 1.5 if the fuels were injected with parallel polarization. Furthermore, our simulations demonstrate additional non-linear power gains in large-scale machines such as ITER, due to increased alpha heating. Such benefits require the survival of spin polarizations for periods comparable to the particle confinement time. During the 1980s, calculations predicted that polarizations could survive a plasma environment, although concerns persisted regarding the cumulative impacts of wall recycling. In that era, technical challenges prevented direct tests and left the large scale fueling of a power reactor beyond reach. Over the last decades, this situation has changed dramatically. Detailed simulations of ITER have predicted negligible wall recycling in a high-power reactor, and recent advances in laser-driven sources project the capability of producing large quantities of ∼100% polarized D and T. The remaining crucial step is an in-situ demonstration of polarization survival in a plasma. For this, we outline a measurement strategy using the isospin-mirror reaction, D + 3 He → α + p. Polarized 3 He avoids the complexities of handling tritium, while encompassing the same spin-physics. We evaluate two methods of delivering deuterium, using dynamically polarized Lithium-Deuteride (with vector polarization P V D of 70%) or frozen-spin Hydrogen-Deuteride (with P V D of 40%), together with a method of injecting optically-pumped 3 He (with 65% polarization). Pellets of these materials all have long polarization decay times (∼6 min for LiD at 2 K, ∼2 months for HD at 2 K, and ∼3 d for 3 He at 77 K), all far greater than a plasma shot in a research tokamak such as DIII-D (∼20 s). Both species can be propelled from a single cryogenic injection gun. We review plasma requirements and strategies for detecting polarization survival. Polarization alters both fusion yields and the angular distribution of fusion products, and each of these provides a potential signal. In this paper we simulate a selection of shots with similar characteristics in a future high-T ion H plasma, and find ratios of yields from shots with fuel spins parallel and antiparallel reaching 1.3 (HD + 3 He) to 1.6 (LiD + 3 He) over a wide range of poloidal angles. (A companion paper finds sensitivity to fusion product angular distributions as reflected in the pitch angles of protons and alphas reaching the plasma facing wall.)

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2023

Entanglement maximization in low-energy neutron-proton scattering

The entanglement properties of neutron-proton scattering are investigated using a measure that counts the number of entangled pairs produced by the action of a scattering operator on a given initial neutron-proton state. All phase shifts relevant for scattering at laboratory energies up to 350 MeV are used. Entanglement is found to depend strongly on the initial state. Entanglement is maximized in very low energy scattering if the initial spin state is | ↑ ↓ >, but not if the initial state is | ↑ ↑ > . At such energies the Hamiltonian obeys Wigner SU(4) symmetry, and an entanglement maximum is a sign of that symmetry. At higher energies the angular dependence of entanglement is strong and the entanglement is large for many scattering angles. Furthermore, the tensor force is shown to play a significant role in producing entanglement at laboratory kinetic energies greater than about 50 MeV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗