Physics Commons^™

Elastic Magnetic Electron Scattering From 'Ca, H Baghaei, A Cichocki, J B. Flanz, M Frodyma, Y Han, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson, S H. Rokni

Gerald Alvin Peterson

The elastic magnetic form factor of 41Ca has been determined by 180° electron scattering in the momentum-transfer range 0.9–2.0 fm-1. An analysis of the data indicates that the amplitudes of the M3 and M5 multipoles are quenched by factors of 0.57±0.16 and 0.68±0.07 relative to the simple shell model. In contrast, the magnitude of the M7 form factor is in good accord with this model. Calculations that include multiparticle-multihole configurations in the 1f7/2 and 1d3/2 subshells, first-order core polarization to higher excited orbitals, and meson exchange currents give reasonable agreement with the data for all multipoles. The rms radius of …

Theory Of Compositional And Magnetic Correlations In Alloys: Interpretation Of A Diffuse Neutron-Scattering Experiment On An Iron-Vanadium Single Crystal, J. B. Staunton, Duane D. Johnson, F. J. Pinski

Duane D. Johnson

We describe a first-principles theory for compositional and magnetic correlations in alloys and compare the results of the theory with recent diffuse, unpolarized, neutron-scattering measurements on a single crystal of ferromagnetic Fe0.865V0.135. The nuclear cross section is described very well by the theory and we are able to connect the q-dependent structure to the underlying electronic structure of the alloy. The magnetocompositional and magnetic correlations also may be obtained for comparison to polarized measurements.

Transverse Electrodisintegration Of The Deuteron In The Threshold Region At High Q2,", R G. Arnold, D Benton, P E. Bosted, L Clogher, B Debebe, M B. Frodyma, R S. Hicks, A Hotta, Gerald Alvin Peterson

Gerald Alvin Peterson

Cross sections for 180° deuteron electrodisintegration have been measured near threshold for the Q2 range 1.21 to 2.77 (GeV/c)2. The data are compared to several nonrelativistic meson-nucleon and hybrid quark-hadron models. The data are in strong disagreement with the impulse approximation, indicating the importance of non-nucleonic degrees of freedom. None of the models are in good agreement with the data at all values of Q2. The ratio W1/W2 of inelastic structure functions has been extracted using previous forward angle data and is found to decrease strongly near threshold, also indicating the importance of interaction effects.

Measurements Of The Deuteron And Proton Magnetic Form Factors At Large Momentum Transfers, P E. Bosted, A T. Katramatou, R G. Arnold, D Benton, L Clogher, G De Chambrier, J Lambert, A Lung, G G. Petratos, A Rahbar, S E. Rock, Z M. Szalata, B Debebe, M Frodyma, R S. Hicks, A Hotta, Gerald Alvin Peterson, R A. Gearhart, J Alster, J Lichtenstadt, F Dietrich, K Van Bibber

Gerald Alvin Peterson

Measurements of the deuteron elastic magnetic structure function B(Q') are reported at squared four-momentum transfer values 1.20~ Qi ~ 2.77 (GeV/c)'. Also reported are values for the proton magnetic form factor Gstr(Q2) at 11 Q values between 0.49 and 1.75 (GeV/c) . The data were obtained using an electron beam of 0.5 to 1.3 GeV. Electrons backscattered near 180' were detected in coincidence with deuterons or protons recoiling near 0 in a large solid-angle double-arm spectrometer system. The data for B(Q ) are found to decrease rapidly from Q =1.2 to 2 (GeV/c), and then rise to a secondary maximum …

Total-Energy And Pressure Calculations For Random Substitutional Alloys, Duane D. Johnson, D. M. Nicholson, F. J. Pinski, B. L. Györffy, G. M. Stocks

Duane D. Johnson

We present the details and the derivation of density-functional-based expressions for the total energy and pressure for random substitutional alloys (RSA) using the Korringa-Kohn-Rostoker Green’s-function approach in combination with the coherent-potential approximation (CPA) to treat the configurational averaging. This includes algebraic cancellation of various electronic core contributions to the total energy and pressure, as in ordered-solid muffin-tin-potential calculations. Thus, within the CPA, total-energy and pressure calculations for RSA have the same foundation and have been found to have the same accuracy as those obtained in similar calculations for ordered solids. Results of our calculations for the impurity formation energy, and …

General Relativity Is Dead, Milan Meszaros

Milan Meszaros physicist

The intent of the present study is to analize standard cosmology in an immanent mathematical-critical way. First of all, the fundamental statements of this cosmological model will be investigated themselves as well as their relevation to the theory. Further aims are to reveal the interdependence of different physical disciplines, confrontation of various observations, to elucidate the correlations between observed data and theory and, finally, to analyze this cosmology from the point of view of self-consistency.

The study discusses the status of the standard modell.

Lowand Mid-Latitude Ionospheric Electric Fields During The January 1984 Gismos Campaign, Bela G. Fejer, M. C. Kelley, C. Senior, O. De La Beaujardiere, J. A. Holt, C. A. Tepley, R. Burnside, M. A. Abdu, J. H.A. Sobral, R. F. Woodman, Y. Kamide, R. Lepping

Bela G. Fejer

This paper examines in detail the electrical coupling between the high-, middle-, and low-latitude ionospheres during January 17–19, 1984, using interplanetary and high-latitude magnetic field data together with F region plasma drift measurements from the EISCAT, Sondre Stromfjord, Millstone Hill, Saint-Santin, Arecibo, and Jicamarca incoherent scatter radars. We study the penetration of both the zonal and meridional electric field components of high-latitude origin into the low-latitude and the equatorial ionospheres. In the dusk sector, a large perturbation of the zonal equatorial electric field was observed in the absence of similar changes at low and middle latitudes in the same longitudinal …

Coincidence Orientations Of Crystals In Tetragonal Systems, With Applications To Yba2cu3o7, Abha Singh, N. Chandrasekhar, Alexander H. King

Alexander H. King

We have developed a method for the characterization of coincidence-site lattices (CSL's) in tetragonal or near-tetragonal orthorhombic structures, by suitable modifications to the method of Grimmer & Warrington [Acta Cryst. (1987), A43, 232-243]. We have applied our method to determine coincidence rotations and the associated information appropriate for forming constrained CSL's in the high-To superconductor YBazCu307-n. The unit cell is orthorhombic with lattice parameters a = 3.82, b = 3"89 and c = 11.67 A for the nominal composition. We present tables of coincidence rotation angles, .Z, CSL, DSCL and associated step vectors up to ,~ = 50. We find …

Seasonal Variations In Theequatorial Thermospheric Wind Measured At Arequipa, Peru, M. A. Biondi, J. W. Meriwether, Bela G. Fejer, S. A. Gonzalez

Bela G. Fejer

Studies have been carried out at Arequipa, Peru, of the seasonal variations in the thermospheric winds at moderate solar flux levels and low geomagnetic activity. Fabry-Perot interferometer measurements of the Doppler shifts in the 630.0 nm nightglow emission line from March to August 1983 and from April to October 1988 have yielded monthly-average meridional winds that are nearly zero (<50 m/s) and possibly fluctuating in direction through much of the night but develop a southward flow at 50–100 m/s in the early and the late night from May onward. The average zonal winds are eastward throughout the night, reaching peak velocities before local midnight and then decreasing. The peak velocities increase to a maximum around the June solstice. The winds are generally stronger in 1988 than in 1983, even though the solar EUV fluxes are comparable for both years. Comparison of the present results with earlier satellite measurements, as embodied in the Horizontal Wind Model of Hedin et al., reveals generally satisfactory agreement at the equinox and June solstice, except for the June 1988 period. Killeen et al.'s vector spherical harmonic form of the NCAR Thermospheric General Circulation Model, calculated for similar solar flux levels, yields meridional and zonal wind variations which exhibit the same temporal behaviors but generally smaller values than the present measurements. The present wind patterns are also compared with those measured during the same years at Arecibo, Puerto Rico; one finds oppositely directed meridional flows and similar, eastward zonal flows at the two locations, as expected from a consideration of solar EUV heating as the principal driving force.