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Full-Text Articles in Physics
Closed-Orbit Theory Of Oscillations In Atomic Photoabsorption Cross Sections In A Strong Electric Field. Ii. Derivation Of Formulas, J. Gao, John B. Delos
Closed-Orbit Theory Of Oscillations In Atomic Photoabsorption Cross Sections In A Strong Electric Field. Ii. Derivation Of Formulas, J. Gao, John B. Delos
Arts & Sciences Articles
A formula for photoabsorption cross sections of hydrogen and alkali-metal atoms in a static electric field is derived, based on the closed-orbit theory previously used to study hydrogen in a magnetic field. Electric fields are simpler than magnetic fields, because the classical motion is regular and closed orbits can be enumerated. In alkali metals the core modifies the relevant dipole matrix elements, and it produces additional phase shifts.
Closed-Orbit Theory Of Oscillations In Atomic Photoabsorption Cross Sections In A Strongelectric Field. I. Comparison Between Theory And Experiments On Hydrogen And Sodium Above Threshold, J. Gao, John B. Delos, M. Baruch
Closed-Orbit Theory Of Oscillations In Atomic Photoabsorption Cross Sections In A Strongelectric Field. I. Comparison Between Theory And Experiments On Hydrogen And Sodium Above Threshold, J. Gao, John B. Delos, M. Baruch
Arts & Sciences Articles
Using a simple analytic formula from closed-orbit theory, we calculate photoabsorption cross sections of hydrogen and sodium in a strong electric field. The theoretical spectra show good agreement with experimental results. A scaled variable measurement is also suggested.
Hamiltonian Bifurcation Theory Of Closed Orbits In The Diamagnetic Kepler Problem, J. M. Mao, John B. Delos
Hamiltonian Bifurcation Theory Of Closed Orbits In The Diamagnetic Kepler Problem, J. M. Mao, John B. Delos
Arts & Sciences Articles
Classically chaotic systems possess a proliferation of periodic orbits. This phenomenon was observed in a quantum system through measurements of the absorption spectrum of a hydrogen atom in a magnetic field. This paper gives a theoretical interpretation of the bifurcations of periodic or closed orbits of electrons in atoms in magnetic fields. We ask how new periodic orbits can be created out of existing ones or ‘‘out of nowhere’’ as the energy changes. Hamiltonian bifurcation theory provides the answer: it asserts the existence of just five typical types of bifurcation in conservative systems with two degrees of freedom. We show …
Quasilinear Theory Of Laser-Plasma Interactions, Alastair John Neil
Quasilinear Theory Of Laser-Plasma Interactions, Alastair John Neil
Dissertations, Theses, and Masters Projects
The interaction of a high intensity laser beam with a plasma is generally susceptible to the filamentation instability due to nonuniformities in the laser profile. In ponderomotive filamentation high intensity spots in the beam expell plasma by ponderomotive force, lowering the local density, causing even more light to be focused into the already high intensity region. The result--the beam is broken up into a filamentary structure.;Several optical smoothing techniques have been proposed to eliminate this problem. In the Random Phase Plates (RPS) approach, the beam is split into a very fine scale, time-stationary interference pattern. The irregularities in this pattern …
The Branching Fraction Of Long-Lived Kaon Going To Muon-Anti-Muon, Michael David Chapman
The Branching Fraction Of Long-Lived Kaon Going To Muon-Anti-Muon, Michael David Chapman
Dissertations, Theses, and Masters Projects
This thesis presents the results of a measurement of the branching fraction of the $K\sb{L}\to\mu\bar{\mu}$ decay. This decay is scGIM supressed in the Standard Model, and provides a useful test of that model. Additionally, the degree of deviation from the unitary limit provides a useful test for several other models. The experiment was performed at the Brookhaven National Laboratory Alternating Gradient Synchrotron facility. The apparatus consisted of a two-magnet mass spectrometer, together with dual electromagnetic and muon particle identification systems. A total of 281 $K\sb{L}\to\mu\bar{\mu}$ events were observed. Normalizing to the 15,768 $K\sb{L}\to\pi\bar{\pi}$ events observed results in a branching fraction …
Painleve Singularity Analysis Applied To Charged Particle Dynamics During Reconnection, Jay Walter Larson
Painleve Singularity Analysis Applied To Charged Particle Dynamics During Reconnection, Jay Walter Larson
Dissertations, Theses, and Masters Projects
For a plasma in the collisionless regime, test-particle modelling can lend some insight into the macroscopic behavior of the plasma, e.g conductivity and heating. A common example for which this technique is used is a system with electric and magnetic fields given by B = {dollar}\delta y{dollar}cx x + xcx y + {dollar}\gamma{dollar}cx z and E = {dollar}\epsilon{dollar}cx z, where {dollar}\delta{dollar}, {dollar}\gamma{dollar}, and {dollar}\epsilon{dollar} are constant parameters. This model can be used to model plasma behavior near neutral lines, ({dollar}\gamma{dollar} = 0), as well as current sheets ({dollar}\gamma{dollar} = 0, {dollar}\delta{dollar} = 0). The integrability properties of the particle motion …
Formation And Desorption Of Negative Ions From Metal Surfaces, Douglas Hugh Baker
Formation And Desorption Of Negative Ions From Metal Surfaces, Douglas Hugh Baker
Dissertations, Theses, and Masters Projects
Investigations of negative ion and electron emission from gas-covered metal surfaces due to the impact of low energy (30-300 eV) positive ions and, separately, photons (2-5 eV) are presented. In both cases, the negative ion formation process is thought to occur via electron tunneling from the surface or its substrate to a sputtered or photodesorbed neutral atom or molecule.;In particular, absolute total negative ion and electron yields for collisions of positive alkali ions with a gas-covered Mo substrate have been measured. Mass analysis of the sputtered negative ions show that O{dollar}\sb2\sp-{dollar} is the dominant ion at low impact energies. This …