Vacancy relaxations in b.c.c. crystals.
Vacancy relaxations in bcc crystals using energy dependence on radial displacements from defect of nearest neighbor sets, discussing crystal size and shape
Grimes, H. H.↗
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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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Physical basis of the transport and composition of cosmic rays in the Galaxy.
Cosmic ray propagation equilibrium model for rays origin and storage in galaxy, considering energy dependence of nuclei relative abundances
Gloeckler, G.↗
Vacuum-ultraviolet photon production in low- energy collisions between two neutral argon atoms
Vacuum UV photons production during ground state neutral argon atomic collisions, measuring relative cross sections energy dependence
Amme, R. C.↗
Analysis of ion-molecule reactions in allene and propyne by ion cyclotron resonance
Thermal product distributions and energy dependencies of ion-molecule reactions in allene and propyne, using ion cyclotron resonance
Bowers, M. T.↗
Shape resonances and rotationally predissociating levels - The atomic collision time delay functions and quasibound level properties of H2/X /1 Sigma g plus//
Approximation of scattering resonance energies and widths of ground state of molecular hydrogen from energy dependence of atomic collisional time delay functions
Bernstein, R. B.↗
Shape resonances and rotationally predissociating levels - The atomic collision time-delay functions and quasibound level properties of H2/chi super 1 sigma sub g plus/
Energy dependence of collisional time delay functions computed for H/1S/ atoms interacting via hydrogen potential, determining scattering cross sections
Bernstein, R. B.↗
SNAP-8 post shutdown gamma radiation approximations
Detector responses were calculated for normalized sources in the Perkins and King energy group structure for a SNAP 8 power system on a NASA space station. Gamma decay rates were then calculated by using an expanded, updated list of isotopic decay data, and from these, actual detector responses were found for the SNAP 8 system. The results indicate that energy-dependent calculations must be made to determine decay gamma dose rates for actual reactor configurations. A simplified method for making these calculations has been devised.
Byrn, N. R.↗
Excitation of Na D-line radiation in collisions of sodium atoms with internally excited H2, D2, and N2
Excitation of D-line radiation in collisions of Na atoms with vibrationally excited N2, H2 and D2 was studied in two modulated crossed beam experiments. In both experiments, the vibrational excitation of the molecules was provided by heating the molecular beam source to temperatures in the range of 2000 to 3000 K, which was assumed to give populations according to the Boltzmann expression. In the first experiment, a total rate coefficient was measured as a function of molecular beam temperature, with absolute calibration of the photon detector being made using the black body radiation from the heated molecular beam source. Since heating affects both the internal energy and the collisional kinetic energy, the first experiment could not determine the relative contributions of internal energy transfer versus collisional excitation. The second experiment achieved partial separation of internal versus kinetic energy transfer effects by using a velocity-selected molecular beam. Using two simple models for the kinetic energy dependence of the transfer cross section for a given change in vibrational quantum number, the data from both experiments were used to determine parameters in the models.
Krause, H. F.↗
NASA-Lewis experiences with multigroup cross sections and shielding calculations
The nuclear reactor shield analysis procedures employed at NASA-Lewis are described. Emphasis is placed on the generation, use, and testing of multigroup cross section data. Although coupled neutron and gamma ray cross section sets are useful in two dimensional Sn transport calculations, much insight has been gained from examination of uncoupled calculations. These have led to experimental and analytic studies of areas deemed to be of first order importance to reactor shield calculations. A discussion is given of problems encountered in using multigroup cross sections in the resolved resonance energy range. The addition to ENDF files of calculated and/or measured neutron-energy-dependent capture gamma ray spectra for shielding calculations is questioned for the resonance region. Anomalies inherent in two dimensional Sn transport calculations which may overwhelm any cross section discrepancies are illustrated.
Lahti, G. P.↗
Entropy and chemical change. 1: Characterization of product (and reactant) energy distributions in reactive molecular collisions: Information and enthropy deficiency
Optimal means of characterizing the distribution of product energy states resulting from reactive collisions of molecules with restricted distributions of initial states are considered, along with those for characterizing the particular reactant state distribution which yields a given set of product states at a specified total energy. It is suggested to represent the energy-dependence of global-type results in the form of square-faced bar plots, and of data for specific-type experiments as triangular-faced prismatic plots. The essential parameters defining the internal state distribution are isolated, and the information content of such a distribution is put on a quantitative basis. The relationship between the information content, the surprisal, and the entropy of the continuous distribution is established. The concept of an entropy deficiency, which characterizes the specificity of product state formation, is suggested as a useful measure of the deviance from statistical behavior. The degradation of information by experimental averaging is considered, leading to bounds on the entropy deficiency.
Bernstein, R. B.↗
Eclipse and noneclipse differential photoelectron flux.
Differential photoelectron flux in the energy range of 3 to 50 eV has been measured in the lower ionosphere both during the March 7, 1970, solar eclipse and during a period 24 hours earlier. The two measurements were made with identical retarding potential analyzers carried on Nike-Apache rocket flights to a peak altitude of approximately 180 km. The differential electron flux spectrum within totality on the eclipse flight had the same shape but was a factor of 10 smaller in magnitude than that measured on the control day at altitudes between 120 and 180 km, an expected result for an eclipse function decreasing to 1/10 at totality. The differential flux spectrum measured in full sun has the same general energy dependence as that reported by Doering et al. (1970) but is larger by a factor of 2 to 10, depending on altitude.
Knudsen, W. C.↗
NASA-Lewis experiences with multigroup cross sections and shielding calculations.
Description of the nuclear reactor shield analysis procedures employed at NASA-Lewis Research Center. Emphasis is placed on the generation, use, and testing of multigroup cross-section data. Although coupled neutron and gamma ray cross-section sets are useful in two-dimensional Sn transport calculations, much insight has been gained from examination of uncoupled calculations. These have led to experimental and analytic studies of areas deemed to be of first-order importance to reactor shield calculations. A discussion is given of problems encountered in using multigroup cross sections in the resolved resonance energy range. The addition to ENDF files of calculated and/or measured neutron-energy-dependent capture gamma ray spectra for shielding calculations is questioned for the resonance region. Anomalies inherent in two-dimensional Sn transport calculations which may overwhelm any cross-section discrepancies are illustrated.
Lahti, G. P.↗
Active tuning circuit
Low-cost, inductorless, high Q active-tuning circuit can be made by coupling pair of transistors and their supporting circuitry to take advantage of frequency dependent energy storage effects. Circuit may be manufactured by standard micro-electronic techniques; has very low noise factor; and input-output matching networks are not necessary.
Kleinberg, L. L.↗
Measurement of Elemental Abundance of Very Low Energy Solar Cosmic Rays
Heavy interplanetary particles were observed during a solar flare period between October 29 and November 4, 1972. The nuclear abundance was determined by a two parameter analysis (dE/dx vs E technique) of a thin window proportional counter - solid state detector device aboard the Explorer 47 (IMP-7) satellite. Energy spectra are given for C, O and Fe. The elemental abundance relative to oxygen is determined for carbon, neon, magnesium, silicon and the iron group in the energy range 0.62 to 6.9 MeV/nucleon. For the Fe/O ratio no energy dependence could be observed within the error limits.
Hovestadt, D.↗
Collision matrix elements near a pseudocrossing of potential energy curves.
The cross sections of certain inelastic atomic collision processes can be determined from the matrix elements of the collision operator, d/dR, where R is the separation of the colliding atoms. At one extreme, the matrix element may pass through zero near a pseudocrossing of potential energy curves, while at the other extreme, it may pass through a maximum. The resulting cross sections are entirely different in magnitude and in energy dependence. An attempt is made to predict the qualitative behavior of the collision matrix elements with variations in R from an analysis of the Born-Oppenheimer adiabatic Hamiltonian. The modifications caused by a second pseudocrossing with a third adiabatic state are studied.
Oppenheimer, M.↗
Electron pitch angle distributions throughout the magnetosphere as observed on Ogo 5.
A survey of the equatorial pitch angle distributions of energetic electrons is provided for all local times out to radial distances of 20 earth radii on the night side of the earth and to the magnetopause on the day side of the earth. In much of the inner magnetosphere and in the outer magnetosphere on the day side of the earth, the normal loss cone distribution prevails. The effects of drift shell splitting - i.e., the appearance of pitch angle distributions with minimums at 90 deg, called butterfly distributions - become apparent in the early afternoon magnetosphere at extended distances, and the distribution is observed in to 5.5 earth radii in the nighttime magnetosphere. Inside about 9 earth radii the pitch angle effects are quite energy-dependent. Beyond about 9 earth radii in the premidnight magnetosphere during quiet times the butterfly distribution is often observed. It is shown that these electrons cannot survive a drift to dawn without being considerably modified. The role of substorm activity in modifying these distributions is identified.
West, H. I., Jr.↗
X-ray evaluation of crystals for stellar spectrometers
The report consists of three parts. The first part is an analysis of the principles involved in X-ray crystal evaluation and how they are applied to a number of crystals. The principles of crystal evaluation analysis as they apply to the special problems of X-ray astronomy are presented. A number of crystals were evaluated, and the energy dependence of the diffraction properties of (002) PET, (111) Ge, (101) ADP, (001) KAP, and (001) RAP are reported. The second part is a compilation of the diffraction properties of a number of crystals as reported by other authors. In the third part some technical details of a triple crystal spectrometer built by the author at Polytechnic Institute of Brooklyn are given. This spectrometer seems to be a most appropriate instrument for evaluation of crystal properties. (Modified author abstract)
Alexandropolos, N. G.↗
A study of X-ray emission from galactic and extragalactic sources with emphasis on soft and ultra-soft wavelengths
A Black Brant VC rocket was used to scan the Coma and Virgo clusters in order to measure structure in the X-ray sources. The rocket also made measurements of soft X-ray spectra, soft X-ray background flux during a 50 deg scan of the sky, soft X-rays from De Voucoulers 50, set limits to the energy dependence of soft X-ray background spectra, and the flux of solar 584 A radiation resonantly scattered by interstellar He flowing through the solar system.
Bowyer, C. S.↗