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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Progress in Understanding Short-Range Structure in Nuclei: An Experimental Perspective

High-energy electron scattering is a clean, precise probe for measurements of hadronic and nuclear structure and plays a key role in understanding the role of high-momentum nucleons (and quarks) in nuclei. Jefferson Lab has dramatically expanded our knowledge of the high-momentum nucleons generated by short-range correlations, providing sufficient insight to model much of their impact on nuclear structure in neutron stars and in low- to medium-energy scattering observables, including neutrino oscillation measurements. These short-range correlations also seem related to the modification of the quark distributions in nuclei, and efforts to improve our understanding of the internal structure of these short-distance and high-momentum configurations in nuclei will provide important input on a wide range of high-energy observables.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Study of correlation effects in nuclei at the limit of stability. Final report

Exotic nuclei far from the valley of stability are a particularly exciting testing ground to probe nucleon-nucleon correlations in a regime where the numbers of constituent protons and neutrons are out of balance and the influence of isospin-dependent terms within the nuclear force becomes amplified. The grant DE-FG02-08ER41556 has supported from 2008 to 2019 an MSU graduate student research assistantship at the heart of a research program that explored the evolution of nuclear structure in exotic nuclei with gamma-ray spectroscopy experiments in the N=40 region of neutron-rich nuclei at NSCL and at ATLAS at Argonne National Laboratory and that mounted a new low-energy Coulomb excitation program at NSCL’s ReA accelerator within the PI’s research program. This final scientific/technical report describes the results and outcomes resulting from the support by the Department of Energy, Office of Science, Office of Nuclear Physics.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Boson Fermion Nuclei Monograph Series: Monograph #6

Monographs 1 through 5 show that nuclei in the second and third periods of the periodic table of elements are made of components that are nuclei in the first period. This leads to descriptions of nuclear structures throughout the periodic table that account for many of the observed properties of nuclei and atoms. The boson fermion nucleus is significant in that it offers a unified explanation for many observables and predicts the creation of materials with extraordinary properties.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2022

Calculation of β- and double β-decay rates in nuclei [Poster]

The knowledge of how neutrinos interact in nuclei is critical to an understanding of finite nuclei, neutrino physics and also to astrophysical environments like neutron stars and supernovae. Within this project we studied how nuclei decay through the emission of a neutrino and a lepton, i.e. β-decay. We implemented realistic treatments of many-nucleon correlations and currents to enable high-precision studies of neutrino physics.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Nuclear Computational Low Energy Initiative (NUCLEI)

The NUCLEI project, as defined by the scope of work, developed, implemented and run codes for large-scale computations of many topics in low-energy nuclear physics. Physics studied include the properties of nuclei and nuclear decays, nuclear structure and reactions, and the properties of nuclear matter. The computational techniques used include Quantum Monte Carlo, Configuration Interaction, Coupled Cluster, and Density Functional methods. The research program emphasized areas of high interest to current and possible future DOE nuclear physics facilities, including ATLAS and FRIB (nuclear structure and reactions, and nuclear astrophysics), TJNAF (neutron distributions in nuclei, few body systems, and electroweak processes), NIF (thermonuclear reactions), MAJORANA and FNPB (neutrinoless double-beta decay and physics beyond the Standard Model), and LANSCE (fission studies).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Investigating Spatial Variability of Aerosol, Cloud Condensation Nuclei, and Ice Nucleating Particles in Mountainous Terrain Field Campaign Report

The U.S. Department of Energy Atmospheric System Research (ASR)-supported Surface Atmosphere Integrated Field Laboratory (SAIL) campaign in the East River Watershed (ERW) of the Upper Colorado River Basin in southwestern Colorado ran from fall 2021 to spring 2023. Two monitoring sites were deployed in the ERW as part of SAIL. The two sites were the Aerosol Observation System (AOS) located on Crested Butte Ski Mountain, and the second ARM Mobile Facility (AMF2), located at the Rocky Mountain Biological Laboratory in Gothic, Colorado. To gain a more comprehensive understanding of aerosols in complex, mountainous terrain, Handix Scientific deployed SAIL-Net, a distributed network of six measurement nodes spanning the domain of the SAIL research area from October 2021 to July 2023. Each node measured aerosol particles between 140 nm and 3.4 μm in diameter using a small portable optical particle spectrometer (POPS; Gao et al. 2016), cloud condensation nuclei (CNN) using a miniature CCN counter (CloudPuck), and ice nucleating particles (INP) using the time-resolved aerosol filter sampler (TRAPS; Creamean et al. 2018). Our approach was similar to other studies that aimed to better characterize and understand aerosols and gas-phase pollutants using networks of lower-cost sensors (Caubel et al. 2019, Kelly et al. 2021, Asher et al. 2022). Such studies have identified neighborhood-level variations in pollutant concentrations (Schneider et al. 2017, Popoola et al. 2018, Caubel et al. 2019). Small-scale variations such as this are poorly represented in models and poorly measured by a single monitoring system (Caubel et al. 2019). Previous work has shown the representation error (the ability of measurements to represent a larger area) increases with complex orography, leading to decreases in model accuracy (Schutgens et al. 2017). The overall goal of SAIL-Net was to improve our understanding of the variability of aerosol in the ERW, thus increasing our knowledge of aerosol-cloud interactions in this region and informing the usefulness of distributed networks of measurements for future studies. We met this goal by answering the following science questions: 1. What is the aerosol temporal variability, and how does aerosol inhomogeneity vary seasonally? Is there significant seasonal variability in sources, or are short-term meteorological conditions the most important determining factor in sources for cloud nuclei? 2. What is the aerosol spatial variability? What are the aerosol characteristics at cloud base, presumably the particles most representative of those acting as cloud nuclei? 3. How should measurement networks be designed to capture aerosol-cloud interactions, and what do they need to measure? Can a single measurement site accurately represent aerosol properties in regions of complex terrain? SAIL-Net consisted of six measurement nodes spread across the ERW near Crested Butte, Colorado. The primary objective in site placement was to select locations that captured the vertical variation in aerosol properties while also spanning the domain of the SAIL campaign. The elevation of the sites ranged from roughly 2750 m along the valley floor of the ERW to approximately 3500 m near the top of Crested Butte Mountain, which is one of the taller peaks in the ERW. The farthest distance between sites was 14 km, while the closest two sites were approximately 1 km apart. Two of the sites were collocated with the ARM SAIL sites; our instruments sat on top of one of the trailers at AOS and another one of our sites was located in a meadow just above AMF2.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Local chiral EFT potentials in nuclei and neutron matter: results and issues

In recent years, the combination of advanced quantum Monte Carlo (QMC) methods and local interactions derived from chiral effective field theory (EFT) has been shown to provide a versatile and systematic approach to nuclear systems. Calculations at next-to-next-to-leading order in chiral EFT have lead to fascinating results for nuclei and nucleonic matter. On the one hand, ground-state properties of nuclei are well reproduced up to A $≤$ 16, even though these potentials have been fit to nucleon-nucleon scattering and few-body observables only. On the other hand, a reasonable description of neutron-matter properties emerges. While regulator functions applied to two- and three-nucleon forces are a necessary ingredient in these many-body calculations, the use of local regulators leads to a substantial residual regulator and cutoff dependence that increases current theoretical uncertainties. In this contribution, we review local chiral interactions, their applications, and QMC results for nuclei and neutron matter. In addition, we address regulator issues for such potentials and present a possible path forward.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Gamma-Ray Spectra of r -process Nuclei

The radioactive decay of unstable nuclei created in the rapid neutron capture process releases a large amount of γ-rays. When the ejecta are optically thick, these γ-rays may contribute to an associated kilonova. Once transparent, prominent spectral features will be directly observable in current and future γ-ray detectors. In this work, we study and compare the γ-ray spectra of different representative r-process trajectories across a broad range of timescales, from hours to 50,000 yr, identifying the nuclei that significantly contribute. We discuss these findings in the context of observability, noting that there are several practical challenges to connecting observed signatures to specific nuclei. However, if these challenges can be overcome, direct observation of γ-rays from r-process sites can provide insight into the fundamental physics underpinning the r-process.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Astromers in the Radioactive Decay of r-process Nuclei

Certain nuclear isomers are well known to affect nucleosynthesis with important observable consequences (e.g., 26 Al and 180 Ta). We study the impact of nuclear isomers in the context of rapid neutron capture process (r-process) nucleosynthesis. Here we demonstrate that nuclear isomers are dynamically populated in the r process and that some are populated far from thermal equilibrium; this makes them astrophysical isomers, or "astromers." We compute thermally mediated transition rates between long-lived isomers and the corresponding ground states in neutron-rich nuclei. We calculate the temperature-dependent β-decay feeding factors, which represent the fraction of material going to each of the isomer and ground state daughter species from the β-decay parent species. We simulate nucleosynthesis following the decay of a solar-like r-process composition and include as separate species nuclear excited states with measured terrestrial half-lives greater than 100 μs. We introduce a new metric to identify those astromers most likely to be influential and summarize them in a table. Notable entries include many second peak nuclei (e.g., the Te isotopic chain) and previously overlooked isomers in stable nuclei (e.g., 119 Sn, 131 Xe, and 195 Pt). Finally, we comment on the capacity of isomer production to alter radioactive heating in an r-process environment.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

MEASUREMENT OF Fn 2 /Fp 2 FROM DEEP INELASTIC ELECTRON SCATTERING OFF A=3 MIRROR NUCLEI AT JEFFERSON LAB

This research is part of the Je?erson Lab MARATHON experiment (MeAsurement of the Fn 2 /Fp 2 , d/u RAtios and A = 3 EMC E?ect in Deep Inelastic Electron Scattering Off the Tritium and Helium MirrOr Nuclei). MARATHON is an experiment on electron deep inelastic scattering off the 3H, 3He mirror nuclei. It has extracted, from the measured deep inelastic scattering cross section ratio o? 3H and 3He, the ratio of the neutron to proton inelastic structure functions Fn 2 /Fp 2 . The extraction has taken advantage of the isospin symmetry of the A = 3 mirror nuclei within a novel technique, which avoids the theoretical uncertainties that are present in the SLAC experiments of the 1970s, which used hydrogen and deuterium targets. The experiment was performed using the upgraded 11 GeV beam of the Jefferson Lab electron accelerator, the Hall A Experimental Facility, and a newly designed cryogenic, high-pressure gas target system containing 3H and 3He cells. Electrons scattered o? the gas targets were detected in the two superconducting, high-resolution magnetic spectrometers of Hall A. The cross section data cover the four-momentum transfer squared range 2.0 < Q2 < 14.0 (GeV/c)2, and the Bjorken x scaling variable range 0.19 < x < 0.83. The experiment also measured, for calibration purposes, electron deep inelastic scattering off hydrogen and deuterium at selected kinematics.

Su, Tong↗
DOE OSTI2020

Measurement of the Ratio of the Neutron to Proton Structure Functions, and the Three-Nucleon EMC Effect in Deep Inelastic Electron Scattering Off Tritium and Helium-3 Mirror Nuclei

The proton and neutron structure functions Fp 2 and Fn 2, respectively are fundamental to understanding many studies in nuclear physics. They provide important information about quark distributions. For example, the ratio Fn 2/Fp 2 is one of the best measurements to find the ratio of d quark over u quark distribution inside the proton. While the calculations of structure functions and quark distributions are non-perturbative, they can be determined by the parameterization of experimental data. The understanding of Fn 2/Fp 2 and d/u as x -> 1 has a large influence on global fits and parameterization, and can be used to distinguish the non-perturbative models which give different predictions. However, Fn 2/Fp 2 measured using deuteron and hydrogen targets has large nuclear uncertainties at large x, because the nuclear effects in the deuteron become significant at large x. The MARATHON experiment, which ran in spring 2018 using the upgraded 11 GeV Jefferson Lab electron beam, employs a novel method. It performed deep inelastic scattering off tritium and helium-3 mirror nuclei to measure Fn 2/Fp 2 over the range x = 0.17 to x = 0.82. Since tritium and helium-3 are mirror nuclei, theoretical uncertainties largely cancel out in the ratio. The extracted Fn 2/Fp 2 has much smaller uncertainties compared with previous experiments at large x. The MARATHON experiment also provided results on the EMC effect for tritium and helium-3 nuclei. The results are considered essential for understanding the EMC effect. This thesis describes the MARATHON experiment, and presents results for Fn 2/Fp 2, and the EMC effect for tritium and helium-3.

Liu, Hanjie↗
DOE OSTI2022

Sensitivity of puff dynamics and airborne droplet nuclei distribution to variations in violent expiration events

Here, we use large eddy simulations to investigate the puff and droplet dynamics from violent expiratory events such as coughs and sneezes in the first few seconds following an ejection. For each of the eleven simulations considered, over 60,000 droplets are ejected and individually tracked using the point-particle Euler–Lagrange approach. We test the sensitivity of the puff and droplet dynamics to various parameters including the ejection volume, momentum, and orientation. We also explore the effect of the mouth shape on the aforementioned dynamics by considering elliptical and circular inlet cross-sections. The results from the simulations compare favorably with a recent theoretical framework put forth by Balachandar et al. in terms of the puff size and propagation velocity. More importantly however, the theory is able to accurately predict the number and size spectra of the potentially virus-laden droplet nuclei that remain airborne within the puff. We observe that the ejection angle and mouth shape do not significantly affect the puff and droplet dynamics. Additionally, we quantify the carrying capacity of the detached puff portions in terms of the number and size spectra of droplets/droplet nuclei suspended within.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

G EANT 4 atomic relaxation data for transfermium nuclei (Z = 101–104)

Advanced theoretical methods can accurately calculate various atomic observables and predict electronic structure. Still, systematic computations of the radiative and non-radiative transition probabilities and energies are missing for the actinides and all the transfermium elements. However, these compilations are needed for comprehensive Monte-Carlo simulations (such as GEANT4) of the radioactive decay of transfermium nuclei. These simulations can forma basis for data analysis of experiments, especially with complex detection setups. Investigation of the transfermium nuclei is crucial for understanding the nature of the nuclear force. In this study, simulations based on data from the Jena Atomic Calculator (JAC) and the data from the Evaluated Atomic Data Library (EADL) present in GEANT4 were found compatible for the three elements Ba(Z = 56), U(Z = 92), and Fm(Z = 100), thus, validating the JAC calculations. For Z> 100, we also found sound agreement between simulations that used data generated with JAC and experimental results involving No(Z = 102) and Rf(Z = 104) isotopes. In conclusion, these results demonstrate that JAC can produce reliable atomic data sets for transfermium elements, which will assist in analyzing nuclear-decay-spectroscopy experiments.

GEANT4↗
DOE OSTI2020

$\gamma$-Unstable Bohr Hamiltonian with sextic potential for odd-A nuclei

We report in this paper, odd-A nuclei in the vibrational to γ-soft transitional region are studied in the collective model, in which the odd-A system is described by the Bohr Hamiltonian with the quasi exactly solvable sextic β-part potential for the even-even core coupled with a single nucleon in a j = 3/2 orbit via the β-independent five-dimensional spin-orbit interaction and the total angular momentum degeneracy breaking term. To test the validity of the coupling scheme, we use the model to reproduce experimentally available level energies and B(E2) values of 187,189,191,193,195 Ir. It is clearly shown from both the level energies and the known B(E2) values for 191,193I r fitted that the model with the β-independent five-dimensional spin-orbit interaction and the total angular momentum degeneracy breaking term seems adequate to describe the low-lying level pattern and the structure of these odd-A nuclei.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Quantitative phase measurements of human cell nuclei using X-ray ptychography

The human cell nucleus serves as an important organelle holding the genetic blueprint for life. In this work, X-ray ptychography was applied to assess the masses of human cell nuclei using its unique phase shift information. Measurements were carried out at the I13-1 beamline at the Diamond Light Source that has extremely large transverse coherence properties. Furthermore, the ptychographic diffractive imaging approach allowed imaging of large structures that gave quantitative measurements of the phase shift in 2D projections. In this paper a modified ptychography algorithm that improves the quality of the reconstruction for weak scattering samples is presented. The application of this approach to calculate the mass of several human nuclei is also demonstrated.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Cloud Condensation Nuclei Particle Counter (CCN) Instrument Handbook

The Cloud Condensation Nuclei Counter—CCN (Figure 1) is a U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility instrument for measuring the concentration of aerosol particles that can act as cloud condensation nuclei [1, 2]. The CCN draws the sample aerosol through a column with thermodynamically unstable supersaturated water vapor that can condense onto aerosol particles. Particles that are activated, i.e., grown larger in this process, are counted (and sized) by an Optical Particle Counter (OPC). Thus, activated ambient aerosol particle number concentration as a function of supersaturation is measured. Models CCN-100 and CCN-200 differ only in the number of humidifier columns and related subsystems: CCN-100 has one column and CCN-200 has two columns along with dual flow systems and electronics.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Cloud Condensation Nuclei Hygroscopicity Value-Added Product Report

The purpose of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility’s Cloud Condensation Nuclei Hygroscopicity Parameter (AOSCCNSMPSKAPPA and AOSCCNUHSASKAPPA) Value-Added Product (VAP) is to calculate the hygroscopicity parameter, kappa, to quantify the ability of aerosols to activate into cloud water droplets. The hygroscopicity parameter is often used to model the cloud condensation nuclei (CCN) activity of atmospheric aerosols of different sizes and compositions, providing additional insight on the influence of aerosols on climate. The AOSCCNUHSASKAPPA VAP was recently developed to provides kappa data for ARM sites where AOSCCNSMPSKAPPA was missing. Laboratory experiments show that the kappa values for highly hygroscopic aerosols vary from 0.5 to 1.4 (Petters and Kreidenweis 2007). For organic compounds they are observed to vary between 0.01 and 0.5. For non-hygroscopic aerosols, such as soot, kappa values are very close to zero. Ambient aerosols are complex mixtures of organic and inorganic compounds and previous observations indicate that kappa values for these aerosols typically vary from 0.05 to 0.9 (Petters and Kreidenweis 2007).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Bayesian averaging for ground state masses of atomic nuclei in a Machine Learning approach

We present global predictions of the ground state mass of atomic nuclei based on a novel Machine Learning algorithm. We combine precision nuclear experimental measurements together with theoretical predictions of unmeasured nuclei. This hybrid data set is used to train a probabilistic neural network. In addition to training on this data, a physics-based loss function is employed to help refine the solutions. The resultant Bayesian averaged predictions have excellent performance compared to the testing set and come with well-quantified uncertainties which are critical for contemporary scientific applications. We assess extrapolations of the model’s predictions and estimate the growth of uncertainties in the region far from measurements.

74 ATOMIC AND MOLECULAR PHYSICS↗