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Articles 32731 - 32760 of 36556

Full-Text Articles in Physical Sciences and Mathematics

Measurements Of Transverse Electron Scattering From The Deuteron In The Threshold Region At High Momentum Transfers, M Frodyma, R G. Arnold, D Benton, P E. Bosted, L Clogher, G Dechambrier, A T. Katramatou, J Lambert, A Lung, G G. Petratos, A Rahbar, S E. Rock, Z M. Szalata, B Debebe, R S. Hicks, A Hotta, Gerald Alvin Peterson Apr 1993

Measurements Of Transverse Electron Scattering From The Deuteron In The Threshold Region At High Momentum Transfers, M Frodyma, R G. Arnold, D Benton, P E. Bosted, L Clogher, G Dechambrier, A T. Katramatou, J Lambert, A Lung, G G. Petratos, A Rahbar, S E. Rock, Z M. Szalata, B Debebe, R S. Hicks, A Hotta, Gerald Alvin Peterson

Gerald Alvin Peterson

Deuteron electrodisintegration cross sections near 180' have been measured near breakup threshold for the four-momentum transfer squared Q' range 1.21—2.76 (GeV/c) . Evidence for a change of slope in the cross section near Q =1 (GeV/c ) has been obtained. The data are compared to nonrelativistic calculations, which predict a strong influence of meson-exchange currents. The data are also compared to a hybrid quark-hadron model ~ None of these calculations agrees with the data over the entire measured range of Q'. The ratio of inelastic structure functions W, (Q', E„~)/Wz(Q', E„~)is extracted from the present results and previous forward angle …

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Monte Carlo Simulations Of Water-Ice Layers On A Model Silver Iodide Substrate: A Comparison With Bulk Ice Systems, James H. Taylor, Barbara N. Hale Apr 1993

Monte Carlo Simulations Of Water-Ice Layers On A Model Silver Iodide Substrate: A Comparison With Bulk Ice Systems, James H. Taylor, Barbara N. Hale

Physics Faculty Research & Creative Works

Two water layers adsorbed on a model silver iodide basal face are simulated at nine temperatures from 150 to 425 K using Monte Carlo methods. The periodic unit cell of 96 internally rigid water molecules (interacting via the revised central-force potentials) couples to the rigid-substrate atoms via effective pair potentials with Lennard-Jones short-range and Coulomb long-range terms. The distribution of molecules perpendicular to the substrate exhibits layering, and individual layer structure factors, dipole moments, and "pseudodiffusion" coefficients are calculated. A complex temperature dependence with the two layers taking on different solidlike, quasiliquid, or liquid properties at the same T is …

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The Effect Of Ionizing And Displacive Radiation On The Thermal Conductivity Of Alumina, D. P. White Apr 1993

The Effect Of Ionizing And Displacive Radiation On The Thermal Conductivity Of Alumina, D. P. White

Physics Faculty Publications

The effects of ionizing and displacive radiation on the thermal conductivity of alumina at high temperatures have been studied. The phonon scattering relaxation times for several scattering mechanisms have been used to determine the effect on the thermal conductivity. The scattering mechanisms considered are scattering by electrons excited into the conduction band, vacancies, aluminum precipitates, and voids. It is found that under irradiation conditions where the electrical conductivity and dielectric loss tangent are greatly increased there is not a significant decrease in the thermal conductivity due to phonon-electron scattering. The conditions under which the scattering due to vacancies, aluminum precipitates, …

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Impurity Modes In Photonic Band Structures, Yi-Fen Chang Apr 1993

Impurity Modes In Photonic Band Structures, Yi-Fen Chang

Masters Theses

In this thesis I study a theoretical model of one-dimensional dielectric array (a layered system of dielectric slabs) which forms a periodic dielectric system in which band gaps are opened in the frequency spectrum. Specifically, we study such a one-dimensional array with linear impurities introduced in the periodic dielectric system. In these impurity structures narrow resonant modes are found in the band gaps as impurity modes and these impurity modes change with the dielectric constant. This impurity problem is similar to the donor and acceptor state problem in electronic semiconductors. The calculations presented in this thesis are based on numerically …

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Electrostatic Positioning Of Droplets In Turbulent Flows (Lstm 375/Te/93), Nihad E. Daidzic, Adrian Melling Apr 1993

Electrostatic Positioning Of Droplets In Turbulent Flows (Lstm 375/Te/93), Nihad E. Daidzic, Adrian Melling

Aviation Department Publications

Report LSTM 375/TE/93, Lehrstuhl fuer Stroemungsmechanik Universitaet Erlangen-Nuernberg Cauerstr. 4, 8520 Erlangen Germany.

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New Magnets From Interstitial Intermetallics, J.M.D. Coey, Ralph Skomski Apr 1993

New Magnets From Interstitial Intermetallics, J.M.D. Coey, Ralph Skomski

Ralph Skomski Publications

The outlook for improving the energy product of permanent magnets beyond the theoretical limit of 516 kJ/m3 for Nd2Fe14B is discussed. Most promising are nanostructured two-phase magnets consisting of an aligned hard-magnetic skeleton phase possessing exceptionally high uniaxial anisotropy and a soft-magnetic phase which assures a high magnetization. Brown’s paradox is discussed for inhomogeneous magnets, and micromagnetic calculations are used to predict energy products as high as 1090 kJ/m3 in suitable nanostructured Sm2Fe17N3/Fe65Co35 composites, such as multilayers or disordered two-phase magnets with common c axis.

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Contribution Of High-Order Rainbows To The Scattering Of A Gaussian Laser Beam By A Spherical Particle, James A. Lock Apr 1993

Contribution Of High-Order Rainbows To The Scattering Of A Gaussian Laser Beam By A Spherical Particle, James A. Lock

Physics Faculty Publications

I review the theory of the scattering of a Gaussian laser beam by a dielectric spherical particle and give the details for constructing a computer program to implement the theory. Computational results indicate that if the width of the laser beam is much less than the diameter of the particle and if the axis of the beam is incident near the edge of the particle, the fifth-, sixth-, and ninth-order rainbows should be evident in the far-field scattered intensity. I performed an experiment that yielded tentative evidence for the presence of the sixth-order rainbow.

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Temperature Dependence Of Optical Properties For Amorphous Silicon At Wavelengths Of 632.8 And 752 Nm, P.T. Leung, Nhan Do, Oguz Yavas, Andrew C. Tam, Wing P. Leung, Hee K. Park, Costas P. Grigoropoulos, Johannes Boneberg, Paul Leiderer Apr 1993

Temperature Dependence Of Optical Properties For Amorphous Silicon At Wavelengths Of 632.8 And 752 Nm, P.T. Leung, Nhan Do, Oguz Yavas, Andrew C. Tam, Wing P. Leung, Hee K. Park, Costas P. Grigoropoulos, Johannes Boneberg, Paul Leiderer

Physics Faculty Publications and Presentations

The temperature dependence of the optical properties for amorphous silicon is studied at wavelengths of 632.8 and 752 nm. Both the refractive index and extinction coefficient increase linearly with temperature for 752 nm, while the refractive index decreases and the extinction coefficient increases for 632.8 nm. The rate of increase of the extinction coefficient at 632.8 nm is twice as much as that for 752 nm.

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Photodeflection Probing Of The Explosion Of A Liquid Film In Contact With A Solid Heated By Pulsed Excimer Laser Irradiation, P.T. Leung, Nhan Do, Leander Klees, Andrew C. Tam, Wing P. Leung Apr 1993

Photodeflection Probing Of The Explosion Of A Liquid Film In Contact With A Solid Heated By Pulsed Excimer Laser Irradiation, P.T. Leung, Nhan Do, Leander Klees, Andrew C. Tam, Wing P. Leung

Physics Faculty Publications and Presentations

The explosion or rapid vaporization of a liquid film on an opaque surface by a pulsed laser is studied experimentally. Using a probe-beam deflection sensing (PDS) scheme, together with a previously developed transmission monitor, the distortion of the PDS signal due to the generation of shock waves by the exploding liquid is investigated. Various liquids, including alcohols and pure water in contact with substrates such as polyimide, amorphous carbon, and silicon, are studied for a wide range of excimer laser fluences. It is concluded that the present PDS technique is highly sensitive to the explosion threshold.

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Photodetachment Cross Section Of H- In Crossed Electric And Magnetic Fields. I. Closed-Orbit Theory, Aaron D. Peters, John B. Delos Apr 1993

Photodetachment Cross Section Of H- In Crossed Electric And Magnetic Fields. I. Closed-Orbit Theory, Aaron D. Peters, John B. Delos

Arts & Sciences Articles

In this, the first of two papers, we obtain a simple analytic formula for the photodetachment cross section of H− in crossed electric and magnetic fields. The three-dimensional semiclassical approximation predicts oscillations in the spectrum and these oscillations are correlated with closed classical orbits. In the following paper [A. D. Peters and J. B. Delos, Phys. Rev. A 47, 3036 (1993)] we derive fully-quantum-mechanical formulas for the cross section in perpendicular electric and magnetic fields and show how these results can be reduced to the semiclassical results of this paper.

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Evidence Of Preferential Directions For Gravity Wave Propagation Due To Wind Filtering In The Middle Atmosphere, Michael J. Taylor, E. H. Ryan, T. F. Tuan, R. Edwards Apr 1993

Evidence Of Preferential Directions For Gravity Wave Propagation Due To Wind Filtering In The Middle Atmosphere, Michael J. Taylor, E. H. Ryan, T. F. Tuan, R. Edwards

All Physics Faculty Publications

All-sky TV images of wave structure in the near-infrared hydroxyl (OH) nightglow emission were recorded over a 3-month period during May, June, and July 1988 from a high-altitude site at the Mountain Research Station (40.0° N, 105.6° W, 3050 m), near Nederland, Colorado. Well-defined, coherent wave patterns associated with the passage of short period (<1 hour) gravity waves were observed on a total of 22 occasions. The wave motions exhibited similar spatial and temporal properties during each month but a distinct tendency for northward propagation (68% of the wave azimuths within ± 40.0° N), with some eastward motion in May and June, was observed throughout the campaign. Although it is theoretically well known that upward propagating gravity waves can be blocked at a critical layer produced by the interaction of the waves with the horizontal background wind, observational evidence of this phenomenon is rare. To investigate the possibility that the asymmetry in the wave propagation directions was caused by the critical layer, a model based on mean climatological background winds and numerical tidal wave modes valid for any mid-latitude site and time of the year was constructed to show the regions forbidden to upward gravity wave propagation from critical layer theory. These “blocking diagrams” which vary with height and time were constructed for the OH altitude (∼87 km) for the present paper. Comparison of the predicted (i.e., least restricted) and the observed directions of the wave motion show almost complete agreement. This suggests that middle atmospheric winds can play an important role in determining the flux and the azimuthal distribution of short-period waves reaching the upper atmosphere.

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Residual-Ion Orientation After Autoionization, G. T. Xu, Xiao Wang, J. Greg Story, William E. Cooke Apr 1993

Residual-Ion Orientation After Autoionization, G. T. Xu, Xiao Wang, J. Greg Story, William E. Cooke

Physics Faculty Research & Creative Works

We have measured the relative population in the two mj states of barium 6p1/2 ions produced by the autoionization of (6p3/2nd)J=MJ=3 states by detecting the helicity of the emitted fluorescence. These populations can be related to the relative branching ratio into the 6p1/2εd5/2 and 6p1/2εg7/2 continuum channels. Rydberg states with n=16-23 have similar branching ratios, producing approximately six times as much 6p1/2εd5/2 population as 6p1/2εg7/2 population.

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Supersymmetry And The Tunneling Problem In An Asymmetric Double Well, Asim Gangopadhyaya, Prasanta K. Panigrahi, Uday P. Sukhatne Apr 1993

Supersymmetry And The Tunneling Problem In An Asymmetric Double Well, Asim Gangopadhyaya, Prasanta K. Panigrahi, Uday P. Sukhatne

Physics: Faculty Publications and Other Works

The techniques of supersymmetric quantum mechanics are applied to the calculation of the energy difference between the ground state and the first excited state of an asymmetric double well. This splitting, originating from the tunneling effect, is computed via a systematic, rapidly converging perturbation expansion. Perturbative calculations to any order can be easily carried out using a logarithmic perturbation theory. Our approach yield substantially better results than alternative widely used semiclassical analyses.

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Millikan Lecture 1992: Hypermedia And The Knowing Of Physics: Standing Upon The Shoulders Of Giants, Robert Fuller Apr 1993

Millikan Lecture 1992: Hypermedia And The Knowing Of Physics: Standing Upon The Shoulders Of Giants, Robert Fuller

Robert G. Fuller Publications

Hypermedia is defined and its roots briefly discussed. Models of knowing physics and of intrinsically motivating instruction are presented. Uses of hypermedia to increase the knowing of physics and the motivation of learners are proposed.

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Filtered Noise Can Mimic Low-Dimensional Chaotic Attractors, P. E. Rapp, Alfonso M. Albano, T. I. Schmah, L. A. Farwell Apr 1993

Filtered Noise Can Mimic Low-Dimensional Chaotic Attractors, P. E. Rapp, Alfonso M. Albano, T. I. Schmah, L. A. Farwell

Physics Faculty Research and Scholarship

This contribution presents four results. First, calculations indicate that when examined by the Grassberger-Procaccia algorithm alone, filtered noise can mimic low-dimensional chaotic attractors. Given the ubiquity Of signal filtering in experimental investigations, this is potentially important. Second, a criterion is derived which provides an estimate of the minimum data accuracy needed to resolve the dimension of an attractor. Third, it is shown that a criterion derived by Eckmann and Ruelle [Physica D 56, 185 (1992)] to estimate the minimum number of data points required in a Grassberger-Procaccia calculation can be used to provide a further check on these dimension estimates. …

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Non-Resonant Transfer And Excitation For S^13+ Projectiles Colliding With Neutral Gas Targets, Liang Duo Apr 1993

Non-Resonant Transfer And Excitation For S^13+ Projectiles Colliding With Neutral Gas Targets, Liang Duo

Masters Theses

Non-resonant Transfer and Excitation (NTE) by 20-70 Mev S,3+ projectiles in collisions with neutral gas targets of He, Ne and Ar is investigated. For NTE, positively charged projectiles undergo excitation and electron capture in a single collision in which the capture and excitation processes are independent events. The mechanisms involved in the NTE process are electron-nucleus interactions, and the combination of projectile excitation and capture is a two-step process. In this work, NTE cross sections, along with total K x-ray production cross sections and total single-electron capture and loss cross sections, were measured as a function of projectile energy. The …

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Photodetachment Cross Section Of H- In Crossed Electric And Magnetic Fields. Ii. Quantum Formulas And Their Reduction To The Result Of The Closed-Orbit Theory, Aaron D. Peters, John B. Delos Apr 1993

Photodetachment Cross Section Of H- In Crossed Electric And Magnetic Fields. Ii. Quantum Formulas And Their Reduction To The Result Of The Closed-Orbit Theory, Aaron D. Peters, John B. Delos

Arts & Sciences Articles

In this, the second of two papers, we derive general quantum formulas for the photodetachment cross section for H− in perpendicular electric and magnetic fields. The results are valid for any polarization and can be reduced to the semiclassical results of the first paper [A. D. Peters and J. B. Delos, Phys. Rev. A 47, 3020 (1993)]: a smooth background plus oscillatory terms. This connection between the quantum and semiclassical results is made using a stationary-phase approximation and it is shown that each stationary-phase point corresponds to a closed orbit.

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The Effects Of Electron Radiation On The Glass Transition Temperature Of A Polyetherimide, Kristen Tulloch Kern Apr 1993

The Effects Of Electron Radiation On The Glass Transition Temperature Of A Polyetherimide, Kristen Tulloch Kern

Physics Theses & Dissertations

The effects of electron radiation on a polyetherimide (PEI), Ultem*, were investigated. In particular, the changes in the glass transition temperature (Tg) with absorbed radiation dose were studied. The polymer was exposed to mono-energetic beams of 100-keV electrons and 1.0-MeV electrons for doses up to 100 megagray (MGy). Dosimetry for the exposures was based on Monte-Carlo simulations of the transfer of energy from an energetic electron to the polymer and on comparison to Nylon standards. Dynamic mechanical analysis was used to determine the (Tg) for non-exposed PEI and the changes in (Tg) resulting from …

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Electron Microscopy Study Of Magnetosomes In Two Cultured Vibrioid Magnetotactic Bacteria, Fiona C. Meldrum, Stephen Mann, Brigid R. Heywood, Richard B. Frankel, Dennis A. Bazylinski Mar 1993

Electron Microscopy Study Of Magnetosomes In Two Cultured Vibrioid Magnetotactic Bacteria, Fiona C. Meldrum, Stephen Mann, Brigid R. Heywood, Richard B. Frankel, Dennis A. Bazylinski

Physics

Magnetite (Fe304) crystals produced by two strains of cultured vibrioid magnetotactic bacteria were studied by high-resolution transmission electron microscopy (HRTEM). Both magnetotactic strains were characterized by single chains of magnetite crystals aligned along the long axes of the cells. The strains, designated as MV-2 and MV-4, produced crystals that differed markedly in size and morphology. Crystals present in MV-4 cells were generally larger than those in MV-2 cells and displayed significantly smaller aspect ratios. Crystallographic analysis of the magnetosomes of MV-2 revealed an elongated hexagonal habit based on a prism of {110} faces capped by {111} …

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Electron Microscopy Study Of Magnetosomes In A Cultured Coccoid Magnetotactic Bacterium, Fiona C. Meldrum, Stephen Mann, Brigid R. Heywood, Richard B. Frankel, D. A. Bazyllinski Mar 1993

Electron Microscopy Study Of Magnetosomes In A Cultured Coccoid Magnetotactic Bacterium, Fiona C. Meldrum, Stephen Mann, Brigid R. Heywood, Richard B. Frankel, D. A. Bazyllinski

Physics

Intracellular magnetite (Fe3O4) crystals produced by the magnetotactic bacterium MC-1 were analyzed by transmission electron microscopy (TEM). Strain MC-1 represents the first-reported isolation of a coccoid magnetotactic bacterium in axenic culture. The magnetosomes of this bacterium displayed a pseudo-hexagonal prismatic habit, were elongated along the crystallographic direction, and were truncated by {111}, {100} and {110} faces. The presence of {111} truncations represents a modification of the magnetosome morphology previously determined for those in other coccoid bacteria. Study of immature crystals produced by strain MC-1 showed that the crystal morphology was controlled even at early stages of …

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Distinguishing A Charged Higgs Signal From A Heavy Wr Signal, David I. Kaiser Mar 1993

Distinguishing A Charged Higgs Signal From A Heavy Wr Signal, David I. Kaiser

Dartmouth Scholarship

It is shown that non-Standard Model bosons should obey an observable asymmetry in their decays to taus. This asymmetry enables a distinction to be made between charged Higgsboson signalsand heavy right-handed Wboson signals,by reconstructing the orientation of the z with respect to the beam axis.

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On Spontaneous Symmetry Breaking In Discretized Light Cone Field Theory, David G. Robertson Mar 1993

On Spontaneous Symmetry Breaking In Discretized Light Cone Field Theory, David G. Robertson

Physics Faculty Scholarship

The problem of spontaneous symmetry breaking in scalar field theories quantized on the light cone is considered. Within the framework of "discretized" light-cone field theory, a constrained zero mode of the scalar field, which is necessary for obtaining a consistent dynamics, is responsible for supporting nonzero vacuum expectation values classically. This basic structure is shown to carry over to the quantum theory as well, and the consistency of the formalism is checked in an explicit perturbative calculation in (1+1)-dimensional φ4 theory.

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Ta(110) Surface And Subsurface Core-Level Shifts And 4f7/2 Lineshapes, D. Mark Riffe, G. K. Wertheim Mar 1993

Ta(110) Surface And Subsurface Core-Level Shifts And 4f7/2 Lineshapes, D. Mark Riffe, G. K. Wertheim

All Physics Faculty Publications

High-resolution 4f core-level spectra of the Ta(110) surface region have been obtained at 80 and 300 K with 70- and 100-eV synchrotron radiation. The data show that the subsurface core-level binding-energy shift (compared to deeper-lying atoms) for a close-packed bcc(110) surface can be substantial: 65±15 meV for the first underlayer atoms of Ta(110). The surface core-level shift is 360±12 meV at 80 K and decreases by 13±2 meV at 300 K. Final-state screening in both the bulk and surface layers is well described by a constant singularity index of 0.133±0.012. An enhanced phonon broadening at the surface corresponds to a …

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Influence Of Retardation On The Vibrational Wave Function And Binding Energy Of The Helium Dimer, Fei Luo, Geunsik Kim, George C. Mcbane, Clayton F. Giese, W. Ronald Gentry Mar 1993

Influence Of Retardation On The Vibrational Wave Function And Binding Energy Of The Helium Dimer, Fei Luo, Geunsik Kim, George C. Mcbane, Clayton F. Giese, W. Ronald Gentry

Peer Reviewed Articles

Because of the extremely small binding energy of the helium dimer, the nuclear wave function is delocalized over an extremely large range of separations. One might therefore expect the properties of this extraordinary species to be sensitive to the potential at very large internuclear distances, r, where relativistic corrections to the usual van der Waals interaction may be important. We have estimated the effect of retardation, which changes the r-6 dependence of the potential to r-7 in the limit of large r, and have found that the binding energy and expectation value (r) are …

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Heavy Quark Solitons, Joseph Schechter, Kumar S. Gupta, M. Arshad Momen, A. Subbaraman Mar 1993

Heavy Quark Solitons, Joseph Schechter, Kumar S. Gupta, M. Arshad Momen, A. Subbaraman

Physics - All Scholarship

We investigate the heavy baryons which arise as solitonic excitations in a ``heavy meson" chiral Lagrangian which includes the light vector particles. It is found that the effect of the light vectors may be substantial. We also present a simple derivation which clearly shows the connection to the Callan-Klebanov approach.

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Doubly Differential Electron-Production Cross Sections For 200- 1500-Ev E- +H2 Collisions, M. Eugene Rudd, K. W. Hollman, J. K. Lewis, D. L. Johnson, R. R. Porter, E. L. Fagerquist Mar 1993

Doubly Differential Electron-Production Cross Sections For 200- 1500-Ev E- +H2 Collisions, M. Eugene Rudd, K. W. Hollman, J. K. Lewis, D. L. Johnson, R. R. Porter, E. L. Fagerquist

M. Eugene Rudd Publications

Ionization cross sections differential in the angle and energy of the detected electrons were measured for electron impact on hydrogen gas at 200, 500, 1000, and 1500 eV. Measurements were made from 15°-150° and from a few eV to T -I where T is the primary electron energy and I the ionization potential of hydrogen. The results are compared to earlier measurements and to available calculations.

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Relative Effectiveness Of Mixed Radiation Fields, Robert Katz Mar 1993

Relative Effectiveness Of Mixed Radiation Fields, Robert Katz

Robert Katz Publications

For all one-hit detectors the relative effectiveness of a mixed radiation field may be found as the dose-weighted average of the relative effectiveness of its components, segregated according to the atomic number Z and the energy T. We emphasize that this procedure is incorrect for mammalian cells, whatever the nature of the segregation.

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The Measurement Of Astronomical Parallaxes With Ccd Imaging Cameras On Small Telescopes, Stephen J. Ratcliff, Thomas J. Balonek, Laurence A. Marschall, David L. Dupuy, Carlton R. Pennypacker, Ritu Verma, Anastasia Alexov, Vivian Bonney Mar 1993

The Measurement Of Astronomical Parallaxes With Ccd Imaging Cameras On Small Telescopes, Stephen J. Ratcliff, Thomas J. Balonek, Laurence A. Marschall, David L. Dupuy, Carlton R. Pennypacker, Ritu Verma, Anastasia Alexov, Vivian Bonney

Physics and Astronomy Faculty Publications

Small telescopes equipped with charge-coupled device (CCD) imaging cameras are well suited to introductory laboratory exercises in positional astronomy (astrometry). An elegant example is the determination of the parallax of extraterrestrial objects, such as asteroids. For laboratory exercises suitable for introductory students, the astronomical hardware needs are relatively modest, and under the best circumstances, the analysis requires little more than arithmetic and a microcomputer with image display capabilities. Results from the first such coordinated parallax observations of asteroids ever made are presented. In addition, procedures for several related experiments, involving single-site observations and/or parallaxes of earth-orbiting artificial satellites, are outlined.

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The Behlen Observatory Variable Star Survey, Paper Iii, Edward G. Schmidt, John R. Chab, Darwin E. Reiswig Mar 1993

The Behlen Observatory Variable Star Survey, Paper Iii, Edward G. Schmidt, John R. Chab, Darwin E. Reiswig

Edward Schmidt Publications

Finding charts, accurate coordinates and light curves are presented for 146 variable stars including three which are newly discovered. Parameters descriptive of the light curves arc tabulated including periods for eight stars which lacked them in the General Catalogue of Variable Stars (the GCVS). GCVS periods of twelve stars were found to be seriously in error. The classification of the stars is discussed. Revisions or refinements of the classifications from the General Catalogue of Variable of Stars are suggested for thirty-one stars. Of the nineteen stars classified as Bailey type c RR Lyrae stars in the General Catalogue of Variable …

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Low Temperature Phase Formation Of Tl-Based Superconducting Thin Films In Reduced Oxygen Atmosphere, C.Y. Wu, F. Foong, Sy_Hwang Liou, J.C. Ho Mar 1993

Low Temperature Phase Formation Of Tl-Based Superconducting Thin Films In Reduced Oxygen Atmosphere, C.Y. Wu, F. Foong, Sy_Hwang Liou, J.C. Ho

Sy-Hwang Liou Publications

Tl-Ba-Cu-Cu-O superconducting thin films were prepared by magnetron sputtering with postannealing in a reduced oxygen atmosphere. Single-phase Tl2Ba2Ca2Cu3Oχ can form on the MgO substrate at 800°C under P(O2)≈0.1 atm. However, the phase formation temperature can be affected by the starting composition of the film. Tl1Ba2 Ca2Cu2Oχ phase can be formed by simply lowering the Tl2O pressure. The thermal stability of Tl1Ba2Ca2Cu3Oχ phase was studied by resistivity measurements at high temperatures.

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