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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Spatial structure of high energy photon sources in solar flares

Stereoscopic observations of high energy (greater than about 100 keV) photon emission from five solar flares have been made with the X-ray spectrometers aboard the ISEE-3 and Pioneer Venus Orbiter spacecraft. The observed altitude structure of the photon source and its dependence on the photon energy and time during a flare are compared with the predictions of thermal and non-thermal models of the hard X-ray source. In the case of the impulsive source, it is found that (1) the thermal model with adiabatic compression and expansion of a magnetically confined plasma and the thin target (non-thermal) model are not consistent with the observations; (2) the thick target (non-thermal) model and the dissipative thermal model are partially in agreement with the observations; (3) the emission probably originates in many individual non-thermal sources distributed in altitude, the lower altitude sources being brighter than those at higher altitude. In the case of the gradual source, it is found that (1) models with purely coronal sources are not consistent with the observations; (2) a partial precipitation model with trapped as well as precipitating electrons is consistent with the observations.

Kane, S. R.↗
DOE OSTI2021

Table-Top High Photon Energy Sources for Chemical Dynamics Investigations

Time-resolved spectroscopies using high-energy photons in the vacuum ultraviolet (VUV) to the X-ray region of the electromagnetic spectrum, have proven to be powerful probes of chemical dynamics. These high-energy photons can access valence and core orbitals of molecules and materials, providing key information on molecular and electronic structure and their time evolution. This report details the development of table-top sources of extreme ultraviolet (XUV) and VUV pulses at Sandia National Laboratories for use in studies of gas phase chemical dynamics. Femtosecond duration XUV pulses are produced using laser-driven high harmonic generation and their detected range span ~40-140 eV photon energies. These pulses are used in conjunction with ultraviolet pulses in a pump-probe scheme to study excited state dynamics of gas phase molecules. VUV pulses at 7.75 eV are generated using a four-wave-mixing scheme driven by 800 nm and 266 nm pulses in an argon-filled hollow-core fiber.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Improvement of machine learning enhanced genetic algorithm for nonlinear beam dynamics optimization

On top of the genetic algorithm enhanced by machine learning for nonlinear lattice optimization, as proposed in Li et al. (2018), an improved repopulation technique has been developed. Different weight coefficients for defining the “elite cluster” were compared to discern the fastest convergence in two classic optimization test problems. Additonally, the volume of the parameter space for generating potentially competitive candidates was further confined by repopulation in the vicinity of randomly selected “elite seeds”. The new repopulation technique significantly improves the quality of newly populated candidates by excluding the less competitive seeds introduced by the old repopulation algorithm. Finally, this technique has been validated, having a faster convergence for test problems first, and then applied to the nonlinear lattice optimization for the High Energy Photon Source storage ring.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Search for Ultra-high-energy Photons from Gravitational Wave Sources with the Pierre Auger Observatory

A search for time-directional coincidences of ultra-high-energy (UHE) photons above 10 EeV with gravitational wave (GW) events from the LIGO/Virgo runs O1 to O3 is conducted with the Pierre Auger Observatory. Due to the distinctive properties of photon interactions and to the background expected from hadronic showers, a subset of the most interesting GW events is selected based on their localization quality and distance. Time periods of 1000 s around and 1 day after the GW events are analyzed. No coincidences are observed. Upper limits on the UHE photon fluence from a GW event are derived that are typically at ~7 MeV cm -2 (time period 1000 s) and ~35 MeV cm -2 (time period 1 day). Due to the proximity of the binary neutron star merger GW170817, the energy of the source transferred into UHE photons above 40 EeV is constrained to be less than 20% of its total GW energy. These are the first limits on UHE photons from GW sources.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Repeatability and sensitivity characterization of the far-field high-energy diffraction microscopy instrument at the Advanced Photon Source

In the last two decades, far-field high-energy diffraction microscopy (FF-HEDM) and similar non-destructive techniques have been actively developed at synchrotron light sources around the world. As these techniques (and associated analysis tools) are becoming more available for the general users of these light sources, it is important and timely to characterize their performance and capabilities. In this work, the FF-HEDM instrument implemented at the 1-ID-E endstation of the Advanced Photon Source (APS) is summarized. The set of measurements conducted to characterize the instrument's repeatability and sensitivity to changes in grain orientation and position are also described. When an appropriate grain matching method is used, the FF-HEDM instrument's repeatability is approximately 5 µm in translation, 0.02° in rotation, and 2 × 10 −4 in strain; the instrument sensitivity is approximately 5 µm in translation and 0.05° in rotation.

3DXRD↗
DOE OSTI2022

High-fidelity photoneutron detection via neutron activation analysis

To interdict illicit radioactive sources and prevent nuclear terror, governments have deployed portal monitor systems at ports of entry. Such portal monitors rely upon the detection of spontaneously-emitted radiation signatures, however, detection scenarios become more challenging for highly enriched uranium, which emits relatively few spontaneous radiation signatures. Photon active interrogation techniques can augment current cargo inspection scenarios and improve detection capabilities for illicit nuclear material. A high-energy photon interrogation source can induce photofission in nuclear material, producing strong radiation signatures for detection. Prompt fission signals are of specific interest because prompt neutrons are greater than 99% of the fission signal. When using detectors capable of spectroscopy, e.g., pulse shape discrimination-capable organic scintillators, the intense interrogating source often will cause pulse pile-up, degrading particle classification. In this work, we demonstrate photoneutron detection via neutron activation of aluminum and iron. The experiments rely upon nuclear reactions that can only be induced by neutrons, and are robust against pile-up, thereby providing high-confidence neutron rates. In this work, we apply neutron activation analysis for the detection of high-energy neutrons produced by high-energy photon irradiation; the depleted uranium sample was irradiated with a 9-MeV bremsstrahlung beam. We find that the irradiated depleted uranium produced an aluminum activation flux of 1.77 × 10 5 n cm –2 s –1 and an iron-56 activation flux of 1.05 × 10 5 n cm –2 s –1 . Furthermore, the ability to detect radioactivity induced by neutrons created in (, n) and photofission reactions demonstrates a new approach for photon active interrogation to identify nuclear materials.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1996

Externally Induced Evaporation of Young Stellar Disks in Orion

In this paper we propose a model for the evaporation of disks around young low-mass stars by external sources of high energy photons. Two evaporation techniques are possible. Lyman continuum radiation can ionize hydrogen at the disk surface powering a steady thermal ionized disk-wind, or FUV radiation can heat the disk through photo-electric grain processes powering a slower thermal neutral disk-wind. Applying these two models to the evaporating objects in the Trapezium produces a satisfactory solution to both the mass-loss rate and size of the ionized envelopes.

Johnstone, D.↗
NASA NTRS2014

An Evaluation of a Passively Cooled Cylindrical Spectrometer Array in Lunar Orbit

This thesis will evaluate a passively cooled cylindrical spectrometer array in lunar orbit characterizing the thermal response in order to provide context for decision-making to scientists and engineers. To provide perspective on thermal issues and controls of space science instruments, a background search of historical lunar missions is provided. Next, a trial science mission is designed and analyzed which brings together the elements of the background search, lunar orbit environment and passive cooling. Finally, the trial science mission analysis results are provided along with the conclusions drawn. Scintillators are materials that when struck by particle radiation, absorb the particle energy which is then reemitted as light in or near the visible range. Nuclear astrophysics utilizes scintillating materials for observation of high-energy photons which are generated by sources such as solar flares, supernovae and neutron stars. SPMs are paired with inorganic scintillators to detect the light emitted which is converted into electronic signals. The signals are captured and analyzed in order to map the number and location of the high-energy sources. The SPM is utilized as it has single photon sensitivity, low voltage requirements and a fast response. SPMs are also compact, relatively inexpensive and allow the usage of lower-cost scintillating materials within the spectrometer. These characteristics permit large-area arrays while lowering cost and power requirements. The ability of a spectrometer to record and identify the interaction of high-energy photons for scientific return is not a trivial matter. Background noise is generated when particles that have not originated from the desired distant source impact the spectrometer. Additionally, thermally induced electrical signals are randomly generated within the SPM even in the absence of light which is referred to as dark current. Overcoming these obstacles requires greater light emittance and energy resolution with reduced dark current. Strong scintillation photon emittance ensures that low energy impacts will produce enough visible photons to be detected by the SPM. Higher energy resolution will ensure that single photon impacts can be distinguished from others of similar wavelength and energy; reduced dark current decreases the generation of random signals not associated with a photon impact. Increasing efficiency in each of these properties in a spectrometer comprised of inorganic scintillators and SPMs requires low temperatures. Low temperature maintenance in a lunar environment presents many unique challenges of its own. Even with the accumulated successes of past missions, the lunar environment remains a thermal challenge for engineers. The lunar orbit thermal environment is driven by radiation from three sources, direct solar radiation, reflected solar radiation from the lunar surface (albedo) and lunar radiation (Clawson 2002). Direct solar radiation values are consistent with those seen in Earth orbit (1325 W/m2) (Clawson 2002). The percentage of solar radiation reflected from the moon is consistently very low with the moon's dark regolith covered surface absorbing nearly 90% of the incident light (Clawson 2002). Yet, it is this absorption that gives the lunar orbit environment one of its most difficult thermal attributes as the absorbed solar radiation is released from the lunar surface as infrared radiation (IR). IR is of a wavelength that is readily absorbed by surfaces designed to function as radiation emitters. It is practical to therefore "choose radiator locations and spacecraft attitude to minimize radiator views to the lunar surface, when possible...pointing the radiator towards the sun to some extent, to minimize its view to the lunar surface, is frequently preferable. (Clawson 2002)" Additionally, the amount of direct solar radiation, lunar IR and albedo an orbiting satellite receives varies from one side of the moon to the other as the moon blocks the sun from view. This environment produces large temperature variations in a satellite's instrumentation, control electronics and propulsion systems which must be understood to characterize operating temperature envelopes.

Waggoner, Jason↗
DOE OSTI2025

SEM/EBSD Characterization of Baffle-Former Bolts Designated for High Energy X-ray Microscopy Studies at the Advanced Photon Source

This report documents the microstructural and surface characterization of two high-fluence baffle-former bolts (BFBs) harvested from a commercial pressurized water reactor (PWR) after nearly four decades of service. These bolts experienced extreme conditions including high neutron fluence, elevated temperatures, corrosive primary water, and sustained mechanical loads, all of which contribute to degradation mechanisms such as irradiation-assisted stress corrosion cracking (IASCC). Using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), the study assessed bulk and near-surface microstructures, grain boundary characteristics, and in-service oxide layers. The results revealed significant differences between bolts exposed to 41 dpa and 29 dpa, including differences in recrystallization extent, deformation structures, and oxidation morphology. These findings establish critical baseline data for integration with advanced synchrotron-based high-energy X-ray microscopy (HEXM) and computational crystal plasticity models. Ultimately, the work supports improved mechanistic understanding and predictive capability regarding the long-term performance of reactor core internal components.

Lach, Tim [Oak Ridge National Laboratory (ORNL), O↗
DOE OSTI2021

Multi-pulse time resolved gamma ray spectroscopy of the advanced radiographic capability using gas Cherenkov diagnostics

The advanced radiographic capability located at the National Ignition Facility (NIF) uses high intensity, short pulse lasers to create bright photon sources for diagnosing high energy density experiments. There are radiographic needs for a multi-frame time-resolved MeV gamma diagnostic for experiments on the NIF with sub-nanosecond resolution. A series of experiments demonstrated measurements of MeV x-ray spectra resolved with a time separation of a few nanoseconds through the use of gas Cherenkov detectors. In this work, a two-pulse radiographic experiment found a 30% reduction in > 2.8 MeV photon flux compared to the first frame exposure.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS2010

The Hard X-Ray Sky: Recent Observational Progress

The last fifty years have witnessed the birth, development, and maturation to full potential of hard X-ray astrophysics. The primary force driving the history of the field has been the development of space-based instrumentation optimized for getting the maximum science out of observations of high-energy photons from astrophysical sources. Hard X-ray telescopes are leading research in areas such as galactic diffuse emission, galactic transients, and active galactic nuclei.

Gehrels, Neil↗
NASA NTRS2011

Future Multiwavelength Studies with the Fermi Large Area Telescope

With two and a half years of experience, Fermi LAT contributions to multiwavelength studies have become an integral part of many astrophysical research projects. Future efforts will benefit from (1) Deeper LAT exposures} resulting in more sources; (2) More high-energy, high-angular resolution photons, giving better source locations and imaging; (3) Faster analysis of variability and announcements to the community; and (4) Longer time series for studies of variable source properties in comparison to other wavelengths.

Thompson, David J.↗
DOE OSTI2020

High-energy-resolution inelastic X-ray scattering spectrometer at beamline 30-ID of the Advanced Photon Source

Inelastic X-ray scattering is a powerful and versatile technique for studying lattice dynamics in materials of scientific and technological importance. In this article, the design and capabilities of the momentum-resolved high-energy-resolution inelastic X-ray spectrometer (HERIX) at beamline 30-ID of the Advanced Photon Source are reported. The instrument operates at 23.724 keV and has an energy resolution of 1.3–1.7 meV. It can accommodate momentum transfers of up to 72 nm -1 , at a typical X-ray flux of 4.5 × 10 9 photons s -1 meV -1 at the sample. A suite of in situ sample environments are provided, including high pressure, static magnetic fields and uniaxial strains, all at high or cryogenic temperatures.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Detectors and diagnostics for multiprobe radiography using high-energy short-pulse lasers

Multiprobe radiography requires the following diagnostic capabilities at minimum: radiographic source diagnostics, spectroscopy, imaging, and tomography diagnostics. Depending on the repetition rate of the radiation sources, the diagnostics may be a single-shot diagnostic, such as photographic (radiochromic and X-ray films for high energy photons) films, or a multiple-shot diagnostic for repetitive source operations, such as a high-speed framing camera. Due to the drastically different detector physics of electrons, photons at different energies (keV to 10s of MeV in the radiography context), heavy ions such as protons, alphas, and neutrons, see, for example, Ref. [1, 2] for an overview, different types or configurations of detectors and constructions may be required for multiprobe radiography applications. Some of the common detector metricsinclude, independent of the particle/photon species, sensitivities or efficiency, energy resolution, spatial or temporal resolutions and others. Some unique detection scenarios arise in a multiprobe radiography setting, for example, crosstalk mitigation and particle identification (ID) when X-ray and higher energy photons, relativistic electrons, neutrons, other hadrons, and heavy particles coexist at the detector location.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗