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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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Exact quantum mechanical reactive cross sections are reported for a three dimensional angle dependent model surface. The surface simulates an atom-heteronuclear diatom system A + BC leading to AB + C where atom B is much heavier than A or C. The molecules BC and AB are taken to be rotating vibrators which can dissociate. Results for two angle dependent potentials are given.
Measurements of the absolute photoionization cross section from the 6s5d 3D metastable level of barium are presented. The 3D levels were selectively populated with a high-power tuneable dye laser. The number density was determined by observing the resulting depopulation of the ground state when pumping occurred.
The results of tests of 56 cylinders of D cross section conducted in the Aeronautical Laboratory of the University of Maryland are presented in this report. These cylinders were subjected to pure bending and torsional moments of varying proportions to give the strength under combined loading conditions. The average buckling stress of these cylinders has been related to that of circumscribing circular cylinders for conditions of pure torsion and pure bending and the equation of the interaction curve has been determined for conditions of combined loading.
Measurements of the normalized radar cross section (sigma(sup o)) made by the YSCAT ultrawideband scatterometer during an extended deployment on the Canada Centre for Inland Waters(CCIW) Research Tower located at Lake Ontario are analyzed and compared with anemometer wind measurements to study the sensitivity of (sigma(sup o)) to the wind speed as a function of the Bragg wavelength. This paper concentrates on upwind and downwind azimuth angles in the wind speed range of 4.5-12 m/s. While YSCAT collected measurements of sigma(sup o) at a variety of frequencies and incidence angles, this paper focuses on frequencies of 2.0, 3.05, 5.30, 10.02, and 14.0 GHz and incidence angles within the Bragg regime, 30-50 deg. Adopting a power law model to describe the relationship between sigma(sup o) and wind speed, both wind speed exponents and upwind/downwind (u/d) ratios of sigma(sup o) are found using least squares linear regression. The analysis of the wind speed exponents and u/d ratios show that shorter Bragg wavelengths (Lambda less than 4 cm) are the most sensitive to wind speed and direction. Additionally, vertical polarization (V-pol) sigma(sup o) is shown to be more sensitive to wind speed than horizontal polarization (H-pol) sigma(sup o), while the H-pol u/d ratio is larger than the V-pol u/d ratio.
We investigate the spatial variability of the normalized radar cross section of the surface (NRCS or Sigma(sup 0)) derived from measurements of the TRMM Precipitation Radar (PR) for the period from 1998 to 2009. The purpose of the study is to understand the way in which the sample standard deviation of the Sigma(sup 0) data changes as a function of spatial resolution, incidence angle, and surface type (land/ocean). The results have implications regarding the accuracy by which the path integrated attenuation from precipitation can be inferred by the use of surface scattering properties.
Differential cross sections for secondary proton production by proton incident beam on beryllium, carbon, water, aluminum, cobalt, and bismuth targets
Point matching method calculation of cut-off frequencies and field configurations of waveguides with general cross section
Charge exchange cross sections for argon ions incident on hydrogen and deuterium measured over energy range of 30 to 1000 ev, taking into account ion-molecule reactions
Charge exchange cross sections measurements for ion-molecule pairs of hydrogen, argon, krypton, helium and xenon
Excitation cross section for doubly ionized states of argon, neon, and krypton by fast electrons
Differential cross sections for secondary protons production in 160 Mev proton reactions on various target nuclei, obtaining angular distributions
Excitation cross section for double ionized states of Ar, Ne and Kr due to fast electron impingement on neutral atom
Cross sections for hydrogen and helium particles produced by 62 MeV and 29 MeV protons on aluminum-27
Ar-Kr integral collision cross sections based on density measurements of Ar beam passed through liquid nitrogen cooled Kr filled scattering chamber
Note on Bell-Kingston paper on Born total and differential cross sections for proton impact ionization of He
Hydrogen and inert gas atoms collisional excitation cross sections calculated by multistate impact parameter approximation
Integral test of inelastic scattering cross sections using measured neutron spectra from thick shells of Ta, W, Mo, and Be
Cross sections for fluorescence production in carbon dioxide photoionization by 58.4 nm radiation, deriving emission spectra