Semiclassical calculation of inelastic cross sections for electron-cesium atomic collisions.
Inelastic cross section calculated semiclassically for electron-cesium atomic collision
INELASTIC COLLISION↗
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Simultaneous ocean cross-section and rainfall measurements from space with a nadir-pointing radar
A method to determine simultaneously the rainfall rate and the normalized backscattering cross section of the surface was evaluated. The method is based on the mirror reflected power, p sub m which corresponds to the portion of the incident power scattered from the surface to the precipitation, intercepted by the precipitation, and again returned to the surface where it is scattered a final time back to the antenna. Two approximations are obtained for P sub m depending on whether the field of view at the surface is either much greater or much less than the height of the reflection layer. Since the dependence of P sub m on the backscattering cross section of the surface differs in the two cases, two algorithms are given by which the path averaged rain rate and normalized cross section are deduced. The detectability of P sub m, the relative strength of other contributions to the return power arriving simultaneous with P sub m, and the validity of the approximations used in deriving P sub m are discussed.
Meneghini, R.↗
Aerodynamic Research on Fuselages with Rectangular Cross Section
The influence of the deflected flow caused by the fuselage (especially by unsymmetrical attitudes) on the lift and the rolling moment due to sideslip has been discussed for infinitely long fuselages with circular and elliptical cross section. The aim of this work is to add rectangular cross sections and, primarily, to give a principle by which one can get practically usable contours through simple conformal mapping. In a few examples, the velocity field in the wing region and the induced flow produced are calculated and are compared with corresponding results from elliptical and strictly rectangular cross sections.
Maruhn, K.↗
Electron collision cross sections in metal vapors Semiannual report
Electron collision cross section in metal vapors - measurement of Townsend alpha coefficient in cesium-helium mixtures
METAL VAPOR↗
A program to measure new energetic particle nuclear interaction cross sections
The Transport Collaboration, consisting of researchers from institutions in France, Germany, Italy, and the USA, has established a program to make new measurements of nuclear interaction cross sections for heavy projectiles (Z greater than or equal to 2) in targets of liquid H2, He and heavier materials. Such cross sections directly affect calculations of galactic and solar cosmic ray transport through matter and are needed for accurate radiation hazard assessment. To date, the collaboration has obtained data using the Lawrence Berkeley Laboratory Bevalac HISS facility with 20 projectiles from He-4 to Ni-58 in the energy range 393-910 MeV/nucleon. Preliminary results from the analysis of these data are presented here and compared to other measurements and to cross section prediction formulae.
Guzik, T. G.↗
Electron impact cross sections for atmospheric species. III.
Inelastic electron impact cross sections for ionization and vibrational excitation of atmospheric molecular oxygen
INELASTIC COLLISION↗
s-wave threshold in electron attachment - Observations and cross sections in CCl4 and SF6 at ultralow electron energies
The threshold photoionization method was used to study low-energy electron attachment phenomena in and cross sections of CCl4 and SF6 compounds, which have applications in the design of gaseous dielectrics and diffuse discharge opening switches. Measurements were made at electron energies from below threshold to 140 meV at resolutions of 6 and 8 meV. A narrow resolution-limited structure was observed in electron attachment to CCl4 and SF6 at electron energies below 10 meV, which is attributed to the divergence of the attachment cross section in the limit epsilon, l approaches zero. The results are compared with experimental collisional-ionization results, electron-swarm unfolded cross sections, and earlier threshold photoionization data.
Chutjian, A.↗
Optical scattering cross sections for polydispersions of dielectric spheres.
Optical scattering cross sections for polydispersions of dielectric spheres, showing dependence on ratio of third to second moment of shape and size distribution function
PARTICLE SIZE↗
Absolute elastic differential electron scattering cross sections in the intermediate energy region. III - SF6 and UF6
A recently developed technique has been used to measure the ratios of elastic differential electron scattering cross sections (DCS) for SF6 and UF6 to those of He at electron impact energies of 5, 10, 15, 20, 30, 40, 50, 60, and 75 eV and at scattering angles of 20 to 135 deg. In order to obtain the absolute values of DCS from these ratios, He DCS of McConkey and Preston have been employed in the 20 to 90 deg range. At angles in the 90 to 135 deg range the recently determined cross sections of Srivastava and Trajmar have been utilized. From these DCS, elastic integral and momentum transfer cross sections have been obtained.
Srivastava, S. K.↗
Total Born approximation cross sections for single electron loss by atoms and ions colliding with atoms
The first born approximation (FBA) is applied to the calculation of single electron loss cross sections for various ions and atoms containing from one to seven electrons. Screened hydrogenic wave functions were used for the states of the electron ejected from the projectile, and Hartree-Fock elastic and incoherent scattering factors were used to describe the target. The effect of the target atom on the scaling of projectile ionization cross sections with respect to the projectile nuclear charge was explored in the case of hydrogen-like ions. Scaling of the cross section with respect to the target nuclear charge for electron loss by Fe (+25) in collision with neutral atoms ranging from H to Fe is also examined. These results were compared to those of the binary encounter approximation and to the FBA for the case of ionization by completely stripped target ions.
Rule, D. W.↗
Fragmentation of 710 and 1050 MeV/nuc Fe nuclei in CH2 and C targets - Isotopic cross sections for H targets
Fe nuclei of incident energies of 710 and 1050 MeV/nuc in CH2 and C targets are fragmented in order to measure isotopic cross sections in hydrogen targets. The telescope used to measure the charge and mass of the fragments is a Cerenkov x total energy telescope. The data are reported for z = 20-25 fragments. The number of individual events corresponding to each charged fragment is obtained and analyzed. Ratios of partial cross sections on C and CH2 targets indicate that simple scaling exists for isotope fractions as well as for charge fractions in different targets. The cross sections in hydrogen are obtained directly by a simple subtraction. Excitation functions for Mn and Cr nuclei are presented.
Webber, W. R.↗
Minimum drag bodies with elliptical cross sections.
Minimum drag bodies with elliptical cross section, using Newtonian flow theory and calculus of variations
VARIATIONAL CALCULUS↗
Nuclear reaction cross sections for spacecraft shield design
Nuclear cross sections and center of sphere dose calculations for spacecraft radiation shielding research
Peelle, R. W.↗
Molecular hydrogen inelastic electron impact cross sections - A semiclassical method.
Electron impact cross sections for diatomic molecule ionization and excitation from modified Gryzinski theory, discussing results from molecular models
Hettel, H. J.↗
Photoionization research on atomic radiation. 3: The ionization cross section of atomic nitrogen
The photoionization cross section of atomic nitrogen was measured between the ionization limit and 432 A. The experimental values are well fitted by those from a calculation of HENRY due to the dipole velocity approximation. A Rydberg series converging to the 5S-state of the ion is clearly identified from the ionization measurements and is shown to ionize.
Comes, F. J.↗
Ab initio method for calculating total cross sections
A method for calculating total cross sections without formally including nonelastic channels is presented. The idea is to use a one channel T-matrix variational principle with a complex correlation function. The derived T matrix is therefore not unitary. Elastic scattering is calculated from T-parallel-squared, but total scattering is derived from the imaginary part of T using the optical theorem. The method is applied to the spherically symmetric model of electron-hydrogen scattering. No spurious structure arises; results for sigma(el) and sigma(total) are in excellent agreement with calculations of Callaway and Oza (1984). The method has wide potential applicability.
Bhatia, A. K.↗
Instantaneous response of elastic thin-walled structures with arbitrary open cross section to rapid heating
A generalized modeling and analysis approach of thermally-induced coupled vibrations of elastic thin-walled configurations with arbitrary open cross sections are presented in conjunction with a unified implicit transient methodology. Limited research appears in literature which takes into account the influence of rapid thermal heating effects on structures involving various forms of coupling. As a consequence, the dynamic response of such thin-walled structures of arbitrary open cross section due to rapid heating are described here. Effects involving triple, double, and no coupling between bending and torsional vibrations caused by sudden heating on these structures are examined. Numerical test cases are presented which describe the influence of sudden heating on elastic thin-walled structures of arbitrary open cross sections.
Chen, Xiaoqin↗
Method of forming variable cross-sectional shaped three-dimensional fabrics
Method of weaving a variable cross-sectional shaped three-dimensional fabric which utilizes different weft yarn insertion from at least one side of the warp layers for selectively inserting weft yarns into different portions of the fabric cross-sectional profile defined by the warp yarn layers during the weaving process. If inserted from both sides of the warp yarn layers, the weft yarns may be inserted simultaneously or alternately from each side of the warp yarn layers. The vertical yarn is then inserted into the fabric by reciprocation of a plurality of harnesses which separate the vertical yarn into a plurality of vertical yarn systems as required by the shape of the three-dimensional fabric being formed.
Mohamed, Mansour H.↗