Relativistic interaction energies between atoms in degenerate states.
Relativistic interaction energies between atoms in degenerate states determined, using Breit-Pauli approximation
QUANTUM MECHANICS↗
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Results for “Atomic energy”
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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Imager of low energy neutral atoms (ILENA) - Imaging neutrals from the magnetosphere at energies below 20 keV
We describe a new imager suitable for measurements of magnetospheric neutrals with energies from about 100 eV to about 10 keV; an energy range adequate for imaging the plasmasheet neutral atoms out to about 10 R(E). The instrument, an outgrowth of a study of atom-surface collisions in support of satellite drag calculations, separates incident photons from neutral atoms by surface scattering and conversion of the neutrals to ions. Subsequently, the ions formed on the first surface are accelerated through a light rejection section which also disperses the ions according to energy. The dispersed ion beam is then allowed to impact a second surface where a start pulse is generated to obtain ion velocity and energy/charge. The second surface is chosen to give large secondary electron emission without regard to charge state of the particles reflected from it. The data supporting the proposed ILENA design is presented in the first part of the paper.
Herrero, Federico A.↗
Atomic electron energies including relativistic effects and quantum electrodynamic corrections
Atomic electron energies have been calculated relativistically. Hartree-Fock-Slater wave functions served as zeroth-order eigenfunctions to compute the expectation of the total Hamiltonian. A first order correction to the local approximation was thus included. Quantum-electrodynamic corrections were made. For all orbitals in all atoms with 2 less than or equal to Z less than or equal to 106, the following quantities are listed: total energies, electron kinetic energies, electron-nucleus potential energies, electron-electron potential energies consisting of electrostatic and Breit interaction (magnetic and retardation) terms, and vacuum polarization energies. These results will serve for detailed comparison of calculations based on other approaches. The magnitude of quantum electrodynamic corrections is exhibited quantitatively for each state.
Aoyagi, M.↗
Atomic ionization: sd energy imbalance and Perdew–Zunger self-interaction correction energy penalty in 3d atoms
To accurately describe the energetics of transition metal systems, density functional approximations (DFAs) must provide a balanced description of s- and d- electrons. One measure of this is the sd transfer error, which has previously been defined as E ( 3 d n − 1 4 s 1 ) − E ( 3 d n − 2 4 s 2 ) . Theoretical concerns have been raised about this definition due to its evaluation of excited-state energies using ground-state DFAs. A more serious concern appears to be strong correlation in the 4s 2 configuration. Here, we define a ground-state measure of the sd energy imbalance, based on the errors of s- and d-electron second ionization energies of the 3d atoms, that effectively circumvents the aforementioned problems. We find an improved performance as we move from the local spin density approximation (LSDA) to the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) to the regularized and restored Strongly Constrained and Appropriately Normed (r 2 SCAN) meta-GGA for first-row transition metal atoms. However, we find large (∼2 eV) ground-state sd energy imbalances when applying a Perdew–Zunger 1981 self-interaction correction. This is attributed to an “energy penalty” associated with the noded 3d orbitals. A local scaling of the self-interaction correction to LSDA results in a balance of s- and d-errors.
Science & Technology - Other Topics↗
The reaction efficiency of thermal energy oxygen atoms with polymeric materials
The reaction efficiency of several polymeric materials with thermal-energy (0.04 eV translational energy), ground-state (O3P) oxygen atoms was determined by exposing the materials to a room temperature gas containing a known concentration of atomic oxygen. The reaction efficiency measurements were conducted in two flowing afterglow systems of different configuration. Atomic oxygen concentration measurements, flow, transport and surface dose analysis is presented in this paper. The measured reaction efficiencies of Kapton, Mylar, polyethylene, D4-polyethylene and Tedlar are .001 to .0001 those determined with high-energy ground-state oxygen atoms in low earth orbit or in a high-velocity atom beam. D4-polyethylene exhibits a large kinetic isotope effect with atomic oxygen at thermal but not hyperthermal atom energies.
Koontz, S. L.↗
A Comparison of the Accuracy of Different Functionals
The errors in the computed geometries, zero-point energies, and atomization energies of molecules containing only first and second row atoms are compared for several levels of theory, including Hartree-Fock, second-order Moller-Plesset perturbation theory (MP2), and density functional theory (DFT) using five different functionals, including two hybrid functionals. The 6-31G* and 6-311+G(3df,2p) basis set are used. Overall, the B3LYP hybrid functional yields the best results.
Bauschlicher, Charles W., Jr.↗
Radiative corrections to the energies of atoms and molecules.
Approximation method using sum rules for energy shift in atomic system due to interaction of electrons with vacuum electromagnetic field applied to hydrogen, helium and lithium atom ground states and hydrogen molecule
HYDROGEN ATOM↗
The scattering of high energy argon atoms from a well characterized /100/ tungsten surface
Scattering of high energy argon atomic beams from /100/ tungsten crystal in gas-surface interaction study
Okeefe, D. R.↗
Experiences with SYCL on AMD GPUs with Kokkos
With the recent diversification of the hardware landscape in the high-performance computing (HPC) community, performance-portability solutions are becoming more and more important. One of the most popular choices is Kokkos, which recently became a Linux Foundation project. Most of its development is supported by the US Department of Energy and the French Alternative Energies and Atomic Energy Commission. Kokkos is implemented as a C++ library with multiple backends to support CPUs as well as various GPU architectures. These backends include OpenMP, CUDA, HIP, and also SCYL. This approach enables users to leverage the preferred vendor toolchain for the respective platform (e.g. CUDA, ROCm, OneAPI). The SYCL backend is used to target Intel GPUs, in particular to support the Aurora exascale supercomputer. However, SYCL itself also offers a large degree of portability, and in fact Kokkos’ CI for SYCL has been running on NVIDIA hardware due to a lack of access to Intel GPUs. In this report, we describe our experience with using Kokkos SYCL backend on AMD GPUs targeting the Frontier supercomputer at Oak Ridge National Laboratory. The two major SYCL implementations are DPC++ and AdaptiveCpp. While the Kokkos SYCL backend has been implemented using the former, the latter was the first implementation to target AMD GPUs. We will discuss the experience with both of these SYCL implementations in terms of functionality and performance. Using Kokkos to evaluate SYCL toolchains has a number of benefits. Kokkos’ use of SYCL is fairly complex, exercising features such as graphs, relocatable device functions, atomics – including for non-arithmetic types, as well as pinned and page migratable memory allocations. Kokkos also needs to implement capabilities such as Kokkos’ hierarchical parallelism that are not a straight-forward mapping to SYCL capabilities. Furthermore, a large number of libraries and applications that represent diverse use cases are implemented in Kokkos, providing readily available test cases for a toolchain evaluation. Preliminary results show that support for AMD GPUs in DPC++ is much less mature than for NVIDIA GPUs or Intel GPUs. While the situation has improved significantly over the last year, we still encounter many runtime failures, dispatching problems, and code generation issues. With AdaptiveCpp the challenges arise even earlier in the evaluation process. Since Kokkos’ SYCL implementation is largely focused on supporting Intel GPUs, we opted to leverage SYCL extensions which are available in DPC++ but not in AdaptiveCpp. Furthermore, AdaptiveCpp appears to be less conformant with the SYCL2020 standard which Kokkos relies on. In some cases, we are able to work around the lack of feature support, in other cases we have to disable certain Kokkos capabilities to evaluate the toolchain. Our evaluation will leverage Kokkos’ unit tests to establish basic functionality and feature completeness. We then use simple benchmarks for components of a CG implementation as a measure of usability and performance of the SYCL toolchains.
97 MATHEMATICS AND COMPUTING↗
Long-Term Infrasound Sensor Calibration and Characterization
Previous testing has shown that infrasound sensors deployed in the field can exhibit notable deviations from their nominal, lab-based calibrations. These variations may be due to changes in environmental conditions, long-term sensor drift, or other unresolved features. In early 2018, we installed two identical infrasound elements with five infrasound sensors at each element (Chaparral M50A, Chaparral M64LN, CEA/Martec MB2005, CEA/Seismowave MB3a, and Hyperion IFS-5113A). These sensors were accepted or under consideration for use in the International Monitoring System network of the Comprehensive Nuclear-Test-Ban Treaty. Each element had all sensors connected to a single digitizer and port to the atmosphere. We also recorded instrument enclosure air temperature and humidity and external air temperature. Using the MB2005 as the reference, we examine the relative sensor response (both magnitude and phase) as a function of time and frequency and compare it with quarterly laboratory calibrations and environmental conditions. Here, we find that the magnitude response for all sensors exhibits some variability in both the lab and field, with the amplitude variations often >5%. The field-based variations are more severe and occur on both long-term (months) and short-term (hours) timescales. Short-term variability correlates with changes in environmental conditions and is considerable (up to 25%) for the Chaparral M50A and noticeable (∼5%) for the French Alternative Energies and Atomic Energy Commission (CEA) MB3a. Long-term magnitude variability for the Chaparral M50A was up to 50% and does not clearly correlate with environmental conditions. The other sensors show some long-term magnitude offsets, but they have relatively stable responses in the conditions we examined. The MB3a also displays some frequency-dependent magnitude variability and shows a minor dependence on temperature. Phase estimates are stable and near zero for all sensors tested. These results strongly suggest sensor response and variability due to environmental conditions should be considered in future infrasound data interpretation and sensor selection and development.
Fee, David↗
Characterizing the Performance of Fission Chambers for Local Neutron Flux and Spectrum Measurement
Three fission chambers were tested at The Ohio State University Research Reactor (OSURR) to evaluate fission chambers for neutron flux and spectrum measurements. Two of the fission chambers are commercial Photonis CFUR43 fission chambers—one utilizing highly enriched uranium-235 fissile deposits for thermal neutron detection and the other with highly depleted uranium-238 for fast neutron detection. This experiment was also performed in collaboration with French Alternative Energies and Atomic Energy Commission (CEA) with CEA suppling a uranium-235 loaded fission chamber built from the Photonis CFPR CE8/9 kit. The fission chambers were irradiated in a movable 6.5 inch dry tube at reactor powers of 50 kW, 200 kW, and 450 kW at ambient temperature and at 350°C. While all sensors demonstrated good linear sensitivity to reactor power, a leakage current of 6 nA was measured for the CFUR43 detectors. Additionally, the measured signal ratios of the two CFUR43 detectors did not match the theoretical values and are subject to further investigation on individual signal contributors.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Keeping LANL at the forefront of list mode capability for safeguards and MC&A [Slides]
Neutron based detection forms key capability to enable and support international and domestic nuclear safeguards and non-proliferation missions. Key stakeholders include International Atomic Energy Agency (IAEA), European Atomic Energy Community (EURATOM), regional safeguards inspectorates, domestic stakeholders. LANL has been historically a leader in development of Non-destructive Assay (NDA) instruments and associated data acquisition hardware and software.
98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
Modeling and Simulation of Austenitic Welds and Coarse-grained Specimens: Part II
The Pacific Northwest National Laboratory (PNNL) is conducting confirmatory research for the U.S. Nuclear Regulatory Commission (NRC) to evaluate commercially available nondestructive examination (NDE) modeling and simulation software used in the nuclear industry. Simulation results from ultrasonic testing (UT) models can inform the design and qualification of inspection techniques and help interpret inspection results. CIVA is a modeling and simulation package developed by the French Alternative Energies and Atomic Energy Commission (CEA). CIVA was selected for this study because it is readily available and has been used for NDE in the US commercial nuclear power industry. This report is focused on completing the efforts initiated in the previous PNNL report to evaluate UT modeling and simulation performance, reliability, and accuracy in relation to common inservice inspection (ISI) scenarios in nuclear power plants (NPP). This work will be used to provide guidance when establishing methods to perform and evaluate simulations for more standardized model implementation, simulation analysis, and interpretation of results.
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
Performance Benchmark of Commercial and Developmental Fission Chambers in Elevated Temperatures
This report documents the testing of two in-core fission chamber technologies for high-temperature irradiation environments. This work is in collaboration with the French Alternative Energies and Atomic Energy Commission (CEA). The fission chamber evaluated by Idaho National Laboratory is the micro-pocket fission detector (MPFD). The fission chamber evaluated by the CEA are the 3 mm miniaturized fission chamber and the 7 mm high-temperature fission chamber. Demonstrations of the MPFD were performed at the Neutron Radiography Facility and the Massachusetts Institute of Technology Reactor. Demonstrations of the CEA fission chambers were performed at the Ohio State University Research Reactor. All demonstrations were conducted with a heated experiment rig up to 850°C.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
2025 CEA SMAD Digitizer Type Approval Evaluation
Sandia National Laboratories has tested and evaluated an updated SMAD digitizer, developed by the French Alternative Energies and Atomic Energy Commission (CEA). The SMAD digitizers are intended to record sensor output for seismic and infrasound monitoring applications.
47 OTHER INSTRUMENTATION↗
Ground Tests on the BOLT Geometry at Mach 7: Cross-Facility Comparison and Stability Analysis
Transition measurements have been obtained through two experimental campaigns conducted independently by the German Aerospace Center and the French Aerospace Lab with the French Alternative Energies and Atomic Energy Commission on subscale models of the BOLT-1 flight experiment geometry. This paper details a cross-facility comparison of measurements obtained at Mach 7, as well as subsequent computational analysis. Infrared (IR) thermography measurements obtained by both campaigns have facilitated a global comparison of the transition front across facilities at analagous conditions, which are found to be in good agreement. High-frequency surface pressure fluctuation data demonstrate significant amplification of instabilities with Mack-mode characteristics in the outboard regions of the acreage. These measurements are compared to stability analyses of varying fidelity. The computational methods employed to characterize the boundary-layer transition phenomena include the traditional line-marching implementation of the Parabolized Stability Equations (PSE), 2D eigenvalue analysis coupled with PSE, and Adaptive Mesh Refinement Wavepacket Tracking. While the 2D eigenvalue analysis is found to predict instabilities, which correlate in terms of frequency and acreage location to the experimental measurements, the predicted amplification for these instabilities is lower than would typically be expected for transition. Line-marching results for traveling crossflow produce the best match to the experimental transition front, with a consistent transition N factor of approximately 3-3.5.
Boundary Layer Transition↗
Comparative assessment of neutron flux sensor technologies for advanced reactors
This report documents the comparative assessment of the rhodium-based self-powered neutron detectors (Rh-SPND), micro-pocket fission detectors (MPFD), and dosimetry wires in heated irradiations at the Neutron Radiography reactor facility at Idaho National Laboratory. The sensors performances are evaluated high-temperature environments (upwards of 850°C) during maximum reactor power to simulate use in advanced reactor applications. The performance of the Rh-SPNDs indicates the experiment cartridge heater power supply interferes with the SPND signals. This interference become increasingly significant at temperatures above 500°C with minimal interference observed for temperatures below 500°C. This work also demonstrated the fabrication process for the updated design of the MPFD, but issues related to the seal welds were identified and usable data was limited. Finally, the dosimetry measurements were within the expected range correlated with reactor power; thus, the dosimetry results were used to provide preliminary SPND calibration factors. The results from this experiment serves as a reference for developing and testing of flux sensors that are designed for high-temperature irradiations and advanced reactor deployments. This includes upcoming FY22 irradiations at the Massachusetts Institute of Technology Reactor and the Neutron Radiography (NRAD) reactor utilizing additional fission chambers from Photonis Technologies and fission chambers and SPNDs from The French Alternative Energies and Atomic Energy Commission.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
A Fifth Force: Generalized through Superconductors
The connection between the Biefield-Brown Effect, the recent repeat of the 1902 Trouton-Noble (TN) experiments, and the gravity shielding experiments was explored. This connection is visualized through high capacitive electron concentrations. From this connection, a theory is proposed that connects mass energy to gravity and a fifth force. The theory called the Gravi-Atomic Energy theory presents two new terms: Gravi-atomic energy and quantum vacuum pressure (QVP). Gravi-atomic energy is defined as the radiated mass energy, which acts on vacuum energy to create a QVP about a mass, resulting in gravity and the fifth force. The QVP emission from a superconductor was discussed followed by the description of a test for QVP from a superconductor using a Cavendish balance.
Robertson, Glen A.↗