Some Aspects of Classical and Quantum Phases

We study classical and quantum phases in the adiabatic Born-Oppenheimer context. These include a classical astronomical case, the general dual description of the phases, a new "Paradox" connected to scattering Berry phase and its resolution and various elaboration of topological/geometrical/non-abelian phases.Comment: 18 pages, 4 figure

Nonlocal Phases of Local Quantum Mechanical Wavefunctions in Static and Time-Dependent Aharonov-Bohm Experiments

We show that the standard Dirac phase factor is not the only solution of the gauge transformation equations. The full form of a general gauge function (that connects systems that move in different sets of scalar and vector potentials), apart from Dirac phases also contains terms of classical fields that act nonlocally (in spacetime) on the local solutions of the time-dependent Schr\"odinger equation: the phases of wavefunctions in the Schr\"odinger picture are affected nonlocally by spatially and temporally remote magnetic and electric fields, in ways that are fully explored. These contributions go beyond the usual Aharonov-Bohm effects (magnetic or electric). (i) Application to cases of particles passing through static magnetic or electric fields leads to cancellations of Aharonov-Bohm phases at the observation point; these are linked to behaviors at the semiclassical level (to the old Werner & Brill experimental observations, or their "electric analogs" - or to recent reports of Batelaan & Tonomura) but are shown to be far more general (true not only for narrow wavepackets but also for completely delocalized quantum states). By using these cancellations, certain previously unnoticed sign-errors in the literature are corrected. (ii) Application to time-dependent situations provides a remedy for erroneous results in the literature (on improper uses of Dirac phase factors) and leads to phases that contain an Aharonov-Bohm part and a field-nonlocal part: their competition is shown to recover Relativistic Causality in earlier "paradoxes" (such as the van Kampen thought-experiment), while a more general consideration indicates that the temporal nonlocalities found here demonstrate in part a causal propagation of phases of quantum mechanical wavefunctions in the Schr\"odinger picture. This may open a direct way to address time-dependent double-slit experiments and the associated causal issuesComment: 49 pages, 1 figure, presented in Conferences "50 years of the Aharonov-Bohm effect and 25 years of the Berry's phase" (Tel Aviv and Bristol), published in Journ. Phys. A. Compared to the published paper, this version has 17 additional lines after eqn.(14) for maximum clarity, and the Abstract has been slightly modified and reduced from the published 2035 characters to the required 1920 character

Chemical cleaning of aluminum alloy surfaces for use as vacuum materials in synchrotron light sources

Photon and electron desorption from the vacuum chamber walls of electron storage rings such as the proposed Advanced Photon Source (APS), are sometimes responsible for the production of large gas loads during operation even in systems with very good static vacuum. The gas released by beam-induced desorption results in scattering of the beam electrons, and a consequent reduction in the beam lifetime. In extreme cases, the beam-induced outgassing may cause so much scattering that it is not possible to obtain the design goals with regard to obtainable beam current. Consequently, it is important that the surfaces which are exposed to the electron beam and photon fluxes contain as little trapped gas as possible, and that the gas burden during operation be kept as low as possible. The current study investigates the effectiveness of a chemical cleaning treatment developed at CERN for the LEP storage ring, as applied to the 6063 alloy to be used in APS. Additionally, depth profiling of the chemically cleaned samples and samples which were vapor-degreased only, provides new insight on the cleaning process as it applies to the alloy proposed for use in APS. 14 refs., 8 figs., 1 tab

Phase Relations in the System Ce2O3-Al2O3 in Inert and Reducing Atmospheres

The 1:1 compound, CeAlO3, in the system Ce2O3-Al2O3 has been synthesized from the oxides and shown to have a perovskite-like tetragonal unit cell with the lattice parameters a = 3.763 and c = 3.792 Angstrom. A new XRD pattern is suggested for CeAlO3. This compound is shown to be stable up to 1950 degrees C. The 1:11 compound, CeAl11O18, has also been synthesized and shown to possess a magnetoplumbite-like hexagonal unit cell with the lattice parameters a = 5.558 and c = 22.012 Angstrom. An XRD pattern is suggested for CeAl11O18 for the first time. The evolution of eutectic-like microstructures was observed and reported in the Ce2O3-rich side of this binary system