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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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Excitation and ionization cross sections for electron scattering in metastable hydrogen atom calculated by Born approximation and Gryzinski semiclassical theory
Atomic beam measure of cesium-cesium total cross section
A sensitive ionization cross section detector for gas chromatography
Numerical evaluation of quantum effects on transport cross sections for Lennard-Jones gas temperature and statistics effects
Molecular inelastic collision cross sections from radiometer force curve
Electron collision cross section in metal vapors
Thermal flutter analysis of booms with open cross section
Boron 10 absorption cross sections from counting ratios measurements of boron trifluoride proportional counter used to monitor neutron fluxes
Photoabsorption cross section data as function of wavelength for 24 atoms
Ionized gases quantum transport cross sections and collision integrals, considering energy and temperature ranges for attractive and repulsive screened Coulomb potentials
A computer subroutine parameterization of electromagnetic dissociation cross sections for nucleus-nucleus collisions is presented that is suitable for implementation in a heavy ion transport code. The only inputs required are the projectile kinetic energy and the projectile and target charge and mass numbers.
Experimental excitation cross sections are reported for the tranitions 3s23p3 S0 goes to 3s23p3 2D0, 3s23p3 P0 and 3s3P4 4P in SII.
The laboratory values of the Herzberg continuum absorption cross-section of oxygen at room temperature from Cheung et al. (1986) and Jenouvrier et al. (1986) are compared and analyzed. It is found that there is no discrepancy between the absolute values of these two sets of independent measurements. The values are combined in a linear least-squares fit to obtain improved values of the Herzberg continuum cross-section of oxygen at room temperature throughout the wavelength region 205-240 nm. The results are compared with in situ and other laboratory measurements.
An analysis is presented of the wave propagation and attenuation in two-dimensional ducts with slowly varying cross sections which carry sheared mean flow. A uniformly valid asymptotic expansion of the acoustic waves is obtained in terms of the maximum slope of the wall by using the method of multiple scales. The result is a first-order differential equation describing the amplitude variation with the axial distance. This equation is used to evaluate the effects of variations of the duct cross section and growing boundary layers on the different acoustic modes.
Using synchrotron radiation as a continuum light source, the photoabsorption and photoionization cross sections of NH3, PH3, H2S, C2H2, and C2H4 have been measured from their respective ionization thresholds to 1060 A. The vibrational constants associated with the nu(2) totally symmetric, out-of-plane bending vibration of the ground electronic state of PH3(+) have been obtained. The cross sections and quantum yields for producing neutral products through photoexcitation of these molecules in the given spectral regions have also been determined. In the present work, autoionization processes were found to be less important than dissociation and predissociation processes in NH3, PH3, and C2H4. Several experimental techniques have been employed in order to examine the various possible systematic errors critically.
Neutrino production in sun, predicting fluxes and absorption cross sections for transitions from ground states, with reference to beta decay rates
Fluctuating light scattering cross section and Lorentz-Lorenz refractive index formula derived from microscopic equations
Measurements and theoretical predictions of the Coulomb cross section for the production of direct electron pairs by heavy ions in emulsion have been performed. Nuclear track emulsions were exposed to the 1.8 GeV/amu Fe-56 beam at the Lawrence Berkeley Laboratory bevalac and to the 60 and 200 GeV/amu O-16 and the 200 GeV/amu S-32 beam at the European Center for Nuclear Research Super Proton Synchrotron modified to accelerate heavy ions. The calculations combine the Weizsacker-Williams virtual quanta method applicable to the low-energy transfers and the Kelner-Kotov relativistic treatment for the high-energy transfers. Comparison of the measured total electron pair yield, the energy transfer distribution, and the emission angle distribution with theoretical predictions revealed a discrepancy in the frequency of occurrence of the low-energy pairs (less than or = 10 MeV). The microscope scanning criteria used to identify the direct electron pairs is described and efforts to improve the calculation of the cross section for pair production are also discussed.