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Heavy ion interactions

Description: Nuclear Physics has come a long way since its inception 70 years ago. We have learned a great deal about nuclear structure and nuclear interactions -- and we have a lot to learn yet. Our understanding of the substructure of protons and neutrons in terms of their elementary' constituents has also evolved to the present level of QCD and the Standard Model. Early work on nuclear reactions involving light projectiles did a great deal in elucidating the characteristic nuclear symmetries and the dyna… more
Date: January 1, 1989
Creator: Schiffer, J.P.
Partner: UNT Libraries Government Documents Department
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Josephson oscillations of charge density waves

Description: The formation of charge density waves in solids was originally proposed as a possible mechanism for superconductivity by Froehlich. Although the experimentally discovered materials with charge density waves (CDW)s are found to have finite resistivity as a result of impurity pinning, they nevertheless reveal many interesting features including motion which is analogous to a resistively shunted Josephson junction of superconductors. The noise spectrum of CDW systems is reviewed with particular em… more
Date: January 1, 1985
Creator: Ruvalds, J. & Tua, P.F.
Partner: UNT Libraries Government Documents Department
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Vortex unbinding in superconducting thin films

Description: The study of the origin of broad resistive transitions in 2D superconducting films requires extremely homogeneous samples. Granular aluminum evaporated onto freshly eleaved mica substrates are shown to satisfy this criterion. Values of T/sub c/, as a function of resistance per square, are in agreement with a one parameter model of independent grains coupled by the Josephson effect, and not the predictions of the Kosterlitz-Thouless vortex unbinding model.
Date: January 1, 1980
Creator: Bancel, P.A. & Gray, K.E.
Partner: UNT Libraries Government Documents Department
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Flux motion and dissipation in high-temperature superconductors

Description: The effects on flux motion and dissipation of interlayer coupling of the Cu-O planes along the c-axis are considered for the high- temperature superconductors (HTS). It is argued that for the highly-anisotropic HTS, the weak interlayer coupling plays a dominant role that can be described by incoherent Josephson tunneling between superconducting Cu-O bi- or tri-layers. In YBa{sub 2}Cu{sub 3}O{sub 7}, the layers are strongly coupled, presumably because the conducting Cu-O chains short circuit the… more
Date: August 1, 1991
Creator: Gray, K.E. & Kim, D.H.
Partner: UNT Libraries Government Documents Department
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Squids, supercurrents, and slope anomalies: Nuclear structure from heavy-ion transfer reactions

Description: Within the past five years we have developed experimental techniques to study heavy-ion transfer reactions to high spin states in deformed nuclei. These methods have been turned into a quantitative tool to assess the influence of collective excitation on single-particle and pairing structure. I discuss some of the nuclear structure questions which are being answered in these experiments: How strong is ground state pairing How does pairing change with angular momentum Why is two-neutron transfer… more
Date: January 1, 1989
Creator: Guidry, M.W.
Partner: UNT Libraries Government Documents Department
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Research and development of superconductivity in the USA

Description: In this paper, the author focuses his attention on the present and potential applications of superconductors -- both the classic low T/sub c/ superconductors such as niobium and its alloys and the new high-T/sub c/ materials. This discussion falls naturally into two broad areas: large scale applications such as magnets and power generators, and small scale applications such as ultrasensitive detectors of electromagnetic radiation and of tiny magnetic fields;
Date: May 1, 1988
Creator: Clarke, J.
Partner: UNT Libraries Government Documents Department
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Atomic physics tests of quantum electrodynamics. [Bound systems, free electron and muon magnetic moments, Josephson effect]

Description: The tests of quantum electrodynamics derived from bound systems and the free electron and muon magnetic moments are reviewed. The emphasis is on the areas in which recent developments in theory or experiment have taken place. Also determinations of the fine structure constant from the Josephson effect and the fine structure of helium are discussed. (JFP)
Date: August 1, 1976
Creator: Mohr, P. J.
Partner: UNT Libraries Government Documents Department
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Superconductivity: Phenomenology

Description: This document discusses first the following topics: (a) The superconducting transition temperature; (b) Zero resistivity; (c) The Meissner effect; (d) The isotope effect; (e) Microwave and optical properties; and (f) The superconducting energy gap. Part II of this document investigates the Ginzburg-Landau equations by discussing: (a) The coherence length; (b) The penetration depth; (c) Flux quantization; (d) Magnetic-field dependence of the energy gap; (e) Quantum interference phenomena; and (f… more
Date: August 1, 1988
Creator: Falicov, L.M.
Partner: UNT Libraries Government Documents Department
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SCALING OF THE SUPERFLUID DENSITY IN HIGH-TEMPERATURE SUPERCONDUCTORS.

Description: A scaling relation N{sub c} {approx} 4.4{sigma}{sub dc}T{sub c} has been observed parallel and perpendicular to the copper-oxygen planes in the high-temperature superconductors; N{sub c} is the spectral weight and {sigma}{sub dc} is the dc conductivity just above the critical temperature T{sub c}. In addition, Nb and Pb also fall close to the this scaling line. The application of the Ferrell-Glover-Tinkham sum rule to the BCS optical properties of Nb above and below T{sub c} yields N{sub c} {ap… more
Date: October 24, 2005
Creator: HOMES, C.C.
Partner: UNT Libraries Government Documents Department
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Magnetotelluric measurements

Description: The ideas of flux quantization and Josephson tunneling are reviewed, and the operation of the dc SQUID as a magnetometer is described. The SQUID currently used for magnetotellurics has a sensitivity of 10/sup -14/ T Hz/sup -1/2/, a dynamic range at 10/sup 7/ in a 1 Hz bandwidth, a frequency response from 0 to 40 kHz, and a slewing rate of 5 x 10/sup -5/T s/sup -1/. Recent improvements in sensitivity are discussed: SQUIDS are rapidly approaching the limit imposed by the uncertainty principle. Th… more
Date: June 1, 1980
Creator: Clarke, John & Goldstein, N. E.
Partner: UNT Libraries Government Documents Department
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Effects of c-axis Josephson coupling on dissipation, flux dynamics and the mechanism of high-T{sub c} superconductivity

Description: Measurements of the c-axis transport in highly anisotropic HTS materials strongly indicate that Josephson coupling is involved. This conclusion affects various properties of the HTS cuprates, including the irreversibility behavior for transport in the ab planes, the direct c-axis transport and potentially the mechanism of Cooper pairing.
Date: December 31, 1995
Creator: Gray, K. E. & Hettinger, J. D.
Partner: UNT Libraries Government Documents Department
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Josephson coupling and plasma resonance in vortex crystal

Description: The authors consider the magnetic field dependence of the plasma resonance frequency in vortex crystal state. The authors found that low magnetic field induces a small correction to the plasma frequency proportional to the field. The slope of this linear field dependence is directly related to the average distance between the pancake vortices in the neighboring layers, wandering length. This length is determined by both Josephson and magnetic couplings between layers. At higher fields the Josep… more
Date: January 19, 2000
Creator: Bulaevskii, L. N. & Koshelev, A. E.
Partner: UNT Libraries Government Documents Department
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Images of interlayer Josephson vortices in single-layer cuprates

Description: The interlayer penetration depth in layered superconductors may be determined from scanning Superconducting QUantum Interference Device (SQUID) microscope images of interlayer Josephson vortices. The authors compare their findings at 4 K for single crystals of the organic superconductor {kappa}-(BEDT-TTF){sub 2}Cu(NCS){sub 2} and three near-optimally doped cuprate superconductors: La{sub 2{minus}x}Sr{sub x}CuO{sub 4}, (Hg, Cu)Ba{sub 2}CuO{sub 4+{delta}}, and Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}}. more
Date: March 1, 2000
Creator: Moler, K. A.; Kirtley, J. R.; Liang, R.; Bonn, D. A.; Hardy, W. N.; Williams, J. M. et al.
Partner: UNT Libraries Government Documents Department
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A compact transportable Josephson voltage standard

Description: The development of a compact, portable 10 V Josephson calibration system is described. Its accuracy is the same as typical laboratory systems and its weight and volume are reduced by more than a factor of three. The new system will replace travelling voltage standards used within several NASA and DOE standards laboratories.
Date: June 1996
Creator: Hamilton, C. A.; Burroughs, C. J. & Kupferman, S. L.
Partner: UNT Libraries Government Documents Department
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