Magnetic field in the SSC arc quad (open access)

Magnetic field in the SSC arc quad

In part one we report on field calculations along the conductor in the end region of the SSC arc-quad. We have determined that the maximum field in the 2D section is 5.04 tesla located at the pole turn of the inner layer somewhere in the middle of the cable (strand 9)(fields are at 6500 A). At the end'' the maximum field is slightly higher 5.09 tesla located at the overpass (strand 11). The iron contribution was included assuming infinite permeability. In part two we include results of a 3D representation of the magnetic field inside the bore. The complete analysis, for which a brief description has been included here, is described elsewhere. This form for presenting the field is suitable for interfacing with other codes that make use of the 3D field components (particle tracking and stability). 69 figs.
Date: April 29, 1991
Creator: Caspi, S.; Helm, M. & Laslett, L.J.
Object Type: Report
System: The UNT Digital Library
Direct, experimental evidence of the Fermi surface in YBa sub 2 Cu sub 3 O sub 7-x (open access)

Direct, experimental evidence of the Fermi surface in YBa sub 2 Cu sub 3 O sub 7-x

We report new measurements of the electron-positron momentum spectra of YBa{sub 2}Cu{sub 3}O{sub 7-x} performed with ultra-high statistical precision. These data differ from previous results in two significant respects: They show the D{sub 2} symmetry appropriate for untwinned crystals and, more importantly, they show unmistakable, statistically significant, discontinuities that are evidence of a major Fermi surface section. These results provide a partial answer to a question of special significance to the study of high temperature superconductors i.e. the distribution of the electrons in the material, the electronic structure. Special consideration has been given both experimentally and theoretically to the existence and shape of a Fermi surface in the materials and to the superconducting gap. There are only three experimental techniques that can provide details of the electronic structure at useful resolutions. They are angular correlation of positron annihilation radiation, ACAR, angle resolved photo emission, PE, and de Haas van Alphen measurements. 11 refs., 4 figs.
Date: April 29, 1991
Creator: Haghighi, H.; Kaiser, J. H.; Rayner, S. L.; West, R. N.; Liu, J. Z.; Shelton, R. et al.
Object Type: Article
System: The UNT Digital Library
Saturation and kinetic issues for optical-field-ionized plasma x-ray lasers (open access)

Saturation and kinetic issues for optical-field-ionized plasma x-ray lasers

Lasing between excited states and the ground state following optical-field ionization is studied. Saturation of an x-ray laser when the lower lasing level is a ground state of a H-like or Li-like ion is discussed. Efficiencies of 10{sup {minus}5} to 10{sup {minus}4} are calculated for the 3d{sub 5/2}--2p{sub 3/2} transition at 98 {Angstrom} in Li-like Ne. The assumption that the fine-structure levels are populated according to their statistical weights is shown to be justified through comparisons with calculations using a detailed atomic model. The effect of saturation by a given fine-structure transition on the populations of the fine-structure levels is analyzed. 4 refs., 2 figs.
Date: April 29, 1991
Creator: Eder, D.C.; Amendt, P.; Rosen, M.D.; Nash, J.K. & Wilks, S.C.
Object Type: Article
System: The UNT Digital Library
National Emergency Powers (open access)

National Emergency Powers

This report the National Emergencies Act (50 U.S.C. 1601-1651) that eliminated or modified some statutory grants of emergency authority, required the President to declare formally the existence of a national emergency and to specify what statutory authority, activated by the declaration, would be used, and provided Congress a means to countermand the President's declaration and the activated authority being sought.
Date: April 29, 1991
Creator: Relyea, Harold C.
Object Type: Report
System: The UNT Digital Library