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DOE OSTI2023

Our teams design high-resolution MeV x-ray radiography systems for National security missions [Poster]

The NNSS has been at the forefront of custom high-fidelity x-ray/gamma radiographic imaging solutions that serve our national security for over five decades. Our radiography team utilizes expertise in physics modeling and analysis, along with optical, mechanical, and electrical design, in close collaboration with our customers, to develop imaging methods and capabilities that go beyond their needs. Conceptual designs are developed through R&D efforts to provide solutions for the specific problem at hand. Field systems are designed and built in-house, then qualified utilizing a range of facilities across the National Security Enterprise. Radiographic imaging systems are deployed by our team in the most challenging environments. The NNSS has a strong math and programming team that provides novel on-site image analysis methods that extract crucial information from data returned in field tests.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2023

Analytical Meridional, Non-Paraxial Ray Tracing

We present an analytical method for non-paraxial, meridional ray tracing through a system of basic geometric surfaces derivable from a generalized ellipse; i.e. the most general ray tracing method for a 2-dimensional system comprised of elliptical, circular, and linear surfaces. This work is meant as a non-small angle generalization of standard ray tracing for geometric optics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2021

Photo-Switching of Protein Dynamical Collectivity

We examine changes in the picosecond structural dynamics with irreversible photobleaching of red fluorescent proteins (RFP) mCherry, mOrange2 and TagRFP-T. Measurements of the protein dynamical transition using terahertz time-domain spectroscopy show in all cases an increase in the turn-on temperature in the bleached state. The result is surprising given that there is little change in the protein surface, and thus, the solvent dynamics held responsible for the transition should not change. A spectral analysis of the measurements guided by quasiharmonic calculations of the protein absorbance reveals that indeed the solvent dynamical turn-on temperature is independent of the thermal stability/photostate however the protein dynamical turn-on temperature shifts to higher temperatures. This is the first demonstration of switching the protein dynamical turn-on temperature with protein functional state. The observed shift in protein dynamical turn-on temperature relative to the solvent indicates an increase in the required mobile waters necessary for the protein picosecond motions, that is, these motions are more collective. Melting-point measurements reveal that the photobleached state is more thermally stable, and structural analysis of related RFP’s shows that there is an increase in internal water channels as well as a more uniform atomic root mean squared displacement. These observations are consistent with previous suggestions that water channels form with extended light excitation providing O2 access to the chromophore and subsequent fluorescence loss. We report that these same channels increase internal coupling enhancing thermal stability and collectivity of the picosecond protein motions. The terahertz spectroscopic characterization of the protein and solvent dynamical onsets can be applied generally to measure changes in collectivity of protein motions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1972

New horizons in astronomy.

Besides the study of astronomy itself, other topics included cover the geological and biological developments on earth and basic physics of matter, heat, and light. Optical and radio telescopes are discussed, as well as photographic and photoelectric means of detection. The immediate solar system is described by topics on the properties and atmospheres of the inner and outer planets, the sun's energy, sunspots, and the solar spectrum. Stars both on and off the main sequence are discussed in terms of distances, intrinsic properties, lifetimes and evolution. The Milky Way is compared to other galaxies in size, star population and structure, and the different galaxy shapes are pictured. Topics of most recent interest are covered by results of the lunar explorations, new concepts of Mars, and problems of space travel. Problems of modern astronomy include pulsars, neutron stars, and quasars.

Brandt, J. C.↗

NASA NTRS1972

Extragalactic X-ray sources.

The extended X-ray sources associated with the Virgo, Perseus, and Coma clusters of galaxies can best be explained as a result of the Compton scattering of relativistic electrons (generated in the radio sources which are present in each of these clusters) on the microwave background radiation. The same physical process involving microwave infrared or optical photons generated in the nuclei of active galaxies may account for the more compact X-ray sources. Thermal bremsstrahlung of hot gas in clusters of galaxies is a less likely source of X-rays.

Brecher, K.↗

NASA NTRS1972

High resolution solar observations from space.

Present ground-based solar observations are limited by the transmission properties of the terrestrial atmosphere, the design of instruments, and the choice of observing locations. Recent improvements in the latter two have made possible observations with MTF around 7% at .5 arc sec and 15% at 1 arc sec. However, the instruments now appear to have been developed as far as the terrestrial atmosphere will permit, and new information will only be determined by space observations. The problems of construction, alignment and thermal control of a very high resolution solar telescope in space are discussed together with various optical systems. The problems of solar physics in which we would expect new information are also discussed, on the basis of recent high-resolution observations from the ground.

Zirin, H.↗

NASA NTRS1973

Application of Fourier analysis to multispectral/spatial recognition

One approach for investigating spectral response from materials is to consider spatial features of the response. This might be accomplished by considering the Fourier spectrum of the spatial response. The Fourier Transform may be used in a one-dimensional to multidimensional analysis of more than one channel of data. The two-dimensional transform represents the Fraunhofer diffraction pattern of the image in optics and has certain invariant features. Physically the diffraction pattern contains spatial features which are possibly unique to a given configuration or classification type. Different sampling strategies may be used to either enhance geometrical differences or extract additional features.

Hornung, R. J.↗

NASA NTRS1976

Solar cell array design handbook, volume 1

Twelve chapters discuss the following: historical developments, the environment and its effects, solar cells, solar cell filters and covers, solar cell and other electrical interconnections, blocking and shunt diodes, substrates and deployment mechanisms, material properties, design synthesis and optimization, design analysis, procurement, production and cost aspects, evaluation and test, orbital performance, and illustrative design examples. A comprehensive index permits rapid locating of desired topics. The handbook consists of two volumes: Volume 1 is of an expository nature while Volume 2 contains detailed design data in an appendix-like fashion. Volume 2 includes solar cell performance data, applicable unit conversion factors and physical constants, and mechanical, electrical, thermal optical, magnetic, and outgassing material properties. Extensive references are provided.

Rauschenbach, H. S.↗

NASA NTRS1979

Interferometric observations of Saturn and its rings at a wavelength of 3.71 per cm

Interferometric observations of Saturn and its rings obtained at the Owens Valley Radio Observatory at a wavelength of 3.71 cm (8085 MHz) are presented. Models of the microwave brightness structure of the Saturn system are fit to the observations in order to estimate the brightness temperatures of the planet and its rings. The models allowed making estimates of the brightness temperatures and optical depths of the A, B, and C rings. The ring brightness temperatures and optical depths are compared with a physical ring model of isotropic scatterers in a layer which is many particles thick. The observations are consistent with particles that conservatively scatter the thermal emission from Saturn to the earth and emit no thermal radiation of their own. However, the particle single-scattering albedo that would be most consistent with the observations is slightly less than unity but probably greater than 0.95. There is evidence indicating that the ring particles must be at least a few centimeters in size.

Schloerb, F. P.↗

NASA NTRS1986

Circumstellar grain formation

Dust formation around cool giant and supergiant stars is examined in terms of grain formulation. Optical properties of small clusters, molecular physics of cluster nucleation and growth, circumstellar mass flows, and their application to alpha Ori are discussed.

Draine, B. T.↗

NASA NTRS1987

The frequency of enhanced star formation in interacting and isolated galaxies

To probe the sensitivity of the star formation rate and extent in galaxies to gravitational encounters, ground based near and mid-infrared and IRAS far-infrared measurements of complete samples of isolated and interacting pairs of galaxies were obtained. The observed infrared properties of the isolated galaxies are used to gauge the magnitude of star formation in galaxies free from external influences, and to define the relationships between morphological type and infrared luminosity. These properties were contrasted with those of the interacting sample to examine the extent to which interactions can enhance or alter the nature of star formation. The mechanisms by which interactions influence activity such as star formation are investigated through correlations of the infrared characteristics with radio and optical measurements, and with morphological and physical parameters such as galaxy types, separations, encounter velocities and interaction types. Limits to the physical extent of the star formation are obtained by comparing the large aperture measurements of IRAS with the small aperture ground based photometry.

Cutri, Roc M.↗

NASA NTRS1986

Intercomparison of independent estimates of cloud properties from simultaneous satellite observations

Preliminary results are reported from comparisons between two techniques for determining the cloud cover fraction within a satellite remote sensing scene. One method (PRM) quantifies cloud-free and cloud-filled areas on the bases of physical relationships between temperature, humidity, cloud optical properties and emitted radiation. The other approach (RSSM) derives the fractional cover from the spatial structure of radiances detected by the sensor. The HIRS (PRM) and the AVHRR (RSSM) instruments, tuned to IR wavelengths, on the TIROS-N polar-orbiting satellite furnished the trial data. Sample results are provided from scans at 15 and 11 microns over the Pacific Ocean.

Coakley, J. A., Jr.↗

NASA NTRS1987

Middle Atmosphere Program. Handbook for MAP, volume 25

GLOBMET (the Global Meteor Observation System) was first proposed by the Soviet Geophysical Committee and was accepted by the Middle Atmosphere Program Steering Committee in 1982. While the atmospheric dynamics data from the system are of primary interest to MAP, GLOBMET also encompasses the astronomical radio and optical observations of meteoroids, and the physics of their interaction with the Earth's atmosphere. These astronomical observations and interactional physics with the Earth's atmosphere are discussed in detail.

Roper, R. G.↗

NASA NTRS1986

Probes and monitors for the study of solidification of molten semiconductors

The purpose is to examine solidification in the LiCl-KCl system to determine if phenomena such as solute rejection can be obseved by laser schlieren imaging. Molten salts have attributes that make them attractive as physical models in solidification studies. With optical techniques of investigation such as schlieren imaging, it is possible to study fluid flow phenomena in molten salts and to watch the trajectory of the solid-liquid interface.

Sadoway, D. R.↗

NASA NTRS1989

The physics and chemistry of the L134N molecular core

The dark cloud L134N is studied in detail via millimeter- and centimeter-wavelength emission-line spectra. A high-density core of molecular gas exists in L134N which has a kinetic temperature of about 12 K, a peak molecular hydrogen density of about 10 exp 4.5/cu cm, and a mass of about 23 solar. The core may be the site of future star formation. Maps of emission from (C-18)O, CS, H(C-13)O(+), SO, NH3, and C3H2 reveal morphologically different distributions resulting in part from both varying physical conditions within the cloud and optical depth effects. Significant differences also exist which are probably due to chemical abundance variations. A consistent set of LTE chemical abundances has been estimated at as many as seven positions, which can be used to constrain chemical models of dark clouds.

Swade, Daryl A.↗

NASA NTRS1992

Isothermal aging effects on PMR-15 resin

Specimens of PMR-15 polyimide neat resin were aged in air at temperatures of 288, 316, and 343 C. Weight losses and dimensional changes were monitored during the course of the exposure time. Physical changes were also observed by optical and electron microscopy. It was found that polyimide polymer degradation occurred within a thin surface layer that developed and grew during thermal aging. The cores of the polymer specimens were protected from oxidative degradation, and they were relatively unchanged by the thermal treatment. Surface cracking was observed at 343 C and was probably due to an interaction between voids and stresses that developed in the surface layer.

Bowles, Kenneth J.↗

NASA NTRS1992

Optical and radio variability in blazars

An analysis is presented of the optical (0.44 micron) and radio flux density variations (4.8, 8.0, and 14.5 GHz) of the five best observed variable AGN, of which three are BL Lac objects and two are optically violent variable (OVV) quasars. For each object the nature of the variability at individual wavelengths is determined by using a structure function analysis and the autocorrelation function as calculated from the discrete correlation technique. Both techniques yield similar results, showing that the optical variations are similar for all objects and are a combination of flicker and shot noise. The radio variability is distinct, being described by shot noise (less variation at short times), with the two OVVs exhibiting the most extreme behavior. The time lag between the variations at the three radio frequencies and the optical flux is studied with the discrete cross-correlation function and the mean variance methods. It is concluded that the optical and radio emitting regions are physically related, exist on distinct time scales, and excite their synchrotron emitting plasmas differently.

Hufnagel, Beth R.↗

NASA NTRS1993

Isothermal aging effects on PMR-15 resin

Bowles, Kenneth J.↗