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Full-Text Articles in Physical Sciences and Mathematics
Recurrences Associated With A Classical Orbit In The Node Of A Quantum Wave Function, John A. Shaw, John B. Delos, Michael Courtney, Daniel Kleppner
Recurrences Associated With A Classical Orbit In The Node Of A Quantum Wave Function, John A. Shaw, John B. Delos, Michael Courtney, Daniel Kleppner
Arts & Sciences Articles
Absorption spectra of atoms in magnetic fields reveal recurrences: manifestations of classical orbits (or quantum wave packets) that go out from the atom and later return. A formula from closed-orbit theory asserts that if the orbit lies on a node of the outgoing wave function, then the strength of the recurrence is zero. New quantum calculations, however, show that the recurrence strength is nonzero, though small. We derive a semiclassical formula for the recurrence strength associated with a classical orbit at a node of the quantum wave function. This formula is compared to the quantum mechanical calculation. Compared to …
Organization Of Sequences Of Bifurcations Of Periodic Orbits, D. A. Sadovskii, J. A. Shaw, John B. Delos
Organization Of Sequences Of Bifurcations Of Periodic Orbits, D. A. Sadovskii, J. A. Shaw, John B. Delos
Arts & Sciences Articles
Numerical calculations have shown that bifurcations of periodic orbits of Hamiltonian systems often occur in organized groups. Normal-form theory provides an explanation.
Closed Orbit Bifurcations In Continuum Stark Spectra, Michael Courtney, Hong Jiao, Neal Spellmeyer, Daniel Kleppner, J. Gao, John B. Delos
Closed Orbit Bifurcations In Continuum Stark Spectra, Michael Courtney, Hong Jiao, Neal Spellmeyer, Daniel Kleppner, J. Gao, John B. Delos
Arts & Sciences Articles
We report an experimental and theoretical study of the effect of bifurcations of closed classical orbits in continuum Stark spectra. Our findings provide a natural way to understand how the spectrum evolves from a simple sinusoidal modulation at positive energy to a quasidiscrete spectrum below the classical ionization limit. The experiment employs scaled-energy spectroscopy of lithium. The results provide the first experimental confirmation of a formulation of closed-orbit theory that provides a quantitative description of the behavior of the spectrum at a bifurcation.
Half-Cycle Pulse Acting On A One-Dimensional Rydberg Atom: Semiclassical Transition Amplitudes In Action And Angle Variables, C. D. Schwieters, John B. Delos
Half-Cycle Pulse Acting On A One-Dimensional Rydberg Atom: Semiclassical Transition Amplitudes In Action And Angle Variables, C. D. Schwieters, John B. Delos
Arts & Sciences Articles
In this paper we derive the expression for the transition coefficient used in the preceding paper [C. D. Schwieters and J. B. Delos, Phys. Rev. A 51, 1023 (1995)] for principal-quantum-number transitions in one-dimensional hydrogen caused by half-cycle pulses. We briefly review the methods of Miller [Adv. Chem. Phys. 25, 69 (1974)] and Marcus [Chem. Phys. Lett. 7, 525 (1970); J. Chem. Phys. 54, 3965 (1971)], and then derive the result using the methods of Maslov and Fedoriuk [Semi-Classical Approximation in Quantum Mechanics, (Reidel, Dordrecht, 1981)]. Also, we examine the approximate reduction of hydrogen …
Semiclassical Treatment Of A Half-Cycle Pulse Acting On A One-Dimensional Rydberg Atom, C. D. Schwieters, John B. Delos
Semiclassical Treatment Of A Half-Cycle Pulse Acting On A One-Dimensional Rydberg Atom, C. D. Schwieters, John B. Delos
Arts & Sciences Articles
The final-state distribution of hydrogen, acted upon by a 1/2-cycle pulse, has been calculated semiclassically for a proposed one-dimensional experiment. This work was motivated by the recent experimental realization of half-cycle pulses by Jones, You, and Bucksbaum [Phys. Rev. Lett. 70, 1236 (1993)] in which preliminary studies of ionization and state redistribution for hydrogenlike atoms were carried out. To simplify the situation theoretically, an experiment is proposed in which an additional weak static electric field is imposed and approximately one-dimensional states are selected. Within this one-dimensional approximation the transition probability to various n states (n is the principal …
Beam Dynamics In The Cebaf Superconducting Cavities, Zenghai Li
Beam Dynamics In The Cebaf Superconducting Cavities, Zenghai Li
Dissertations, Theses, and Masters Projects
This work is a study of beam dynamics in the CEBAF superconducting cavities under the influence of the fields generated by externally applied RF and beam particles.;A full 3-D modeling of the CEBAF 5-cell superconducting cavity is carried out. Details of the modeling with MAFIA are discussed. Multipole fields due to the asymmetric couplers are studied by means of 3-D Fourier transforms. The cavity steering and focusing of the multipole fields are studied. Experimental measurements of these effects are performed to validate the modeling. Evaluation of the cavity misalignment is discussed. The emittance degradation effects in the CEBAF superconducting linacs …
The Characterization Of The Radiative Energy Transfer Process Among Holmium(3+) Ions In Yttrium(3) Aluminum(5) Oxygen(12), Terri Lynn Lazarus
The Characterization Of The Radiative Energy Transfer Process Among Holmium(3+) Ions In Yttrium(3) Aluminum(5) Oxygen(12), Terri Lynn Lazarus
Dissertations, Theses, and Masters Projects
This research comprises a comprehensive spectroscopic study of the characteristics of the solid state crystal YAG (Yttrium Aluminum Garnet) singly doped with Ho (Holmium) ions. An important area of solid state laser crystal research is the determination and optimization of the processes within these laser crystals which lead to efficient laser action. In most laser crystals, there is a donor ion such as Tm (Thulium) and an acceptor ion such as Ho. The donor ion generally has greater absorption than that of the acceptor at the wavelength of the pump source. The donor ion can transfer this absorbed energy to …
Search For Metastability Of 2s Muonic Neon, Bernard Wilhelm Bach
Search For Metastability Of 2s Muonic Neon, Bernard Wilhelm Bach
Dissertations, Theses, and Masters Projects
An experiment was performed at the Paul Scherrer Institut (PSI) to establish the conditions for the metastability of the 2S-state of muonic neon. The muonic atoms were formed by stopping negative muons in the neon-filled target chamber of the PSI cyclotron trap. A pair of intrinsic germanium detectors were used in coincidence to search for the two photon decay of the 2S-state. Both energy and time information from two photon events were written to disk for off-line analysis. Data were accumulated for neon pressures of 40 and 400 Torr. The data were then searched for evidence of two photon transitions …
A Delta-F Monte Carlo Method To Calculate Parameters In Plasmas, Maciek Sasinowski
A Delta-F Monte Carlo Method To Calculate Parameters In Plasmas, Maciek Sasinowski
Dissertations, Theses, and Masters Projects
A Monte Carlo code has been developed which very efficiently calculates plasma parameters, such as currents, potentials and transport coefficients for a fully three dimensional magnetic field configuration. The code computes the deviation, f, of the exact distribution function, f, from the Maxwellian, {dollar}F\sb{lcub}M{rcub},{dollar} with {dollar}\psi{dollar} the toroidal magnetic flux enclosed by a pressure surface and H the Hamiltonian. The particles in the simulation are followed with a traditional Monte Carlo scheme consisting of an orbit step in which new values for the positions and momenta are obtained and a collision step in which a Monte Carlo equivalent of the …
First Principles Linear Response Calculations Of Lattice Dynamics, Cheng-Zhang Wang
First Principles Linear Response Calculations Of Lattice Dynamics, Cheng-Zhang Wang
Dissertations, Theses, and Masters Projects
First principles calculations, using the density-functional theory and particularly the local density approximation (LDA), have achieved remarkable success in studying the properties of solid state systems. Although the basic results of these calculations are the electronic structures (eigenvalues, eigenfunctions, etc.) and the total energy of ground state, many other related physical properties can be deduced from them by investigating their response under external perturbations. Using the linear response method with linearized-augmented-plane-wave (LAPW) basis, we have calculated lattice dynamical properties of important semiconductors CuCl, SiC and ferroelectric KNbO{dollar}\sb3.{dollar} CuCl is known to exhibit large anharmonic effects and possibly a complicated multi-well …
Calculations Of The Interactions Of Energetic Ions With Materials For Protection Of Computer Memory And Biological Systems, Myung-Hee Y. Kim
Calculations Of The Interactions Of Energetic Ions With Materials For Protection Of Computer Memory And Biological Systems, Myung-Hee Y. Kim
Dissertations, Theses, and Masters Projects
Theoretical calculations were performed for the propagation and interactions of particles having high atomic numbers and energy through diverse shield materials including polymeric materials and epoxy-bound lunar regolith by using transport codes for laboratory ion beams and the cosmic ray spectrum. Heavy ions fragment and lose energy upon interactions with shielding materials of specified elemental composition, density, and thickness. A fragmenting heavy iron ion produces hundreds of isotopes during nuclear reactions, which are treated in the solution of the transport problem used here. A reduced set of 80 isotopes is sufficient to represent the charge distribution, but a minimum of …