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Full-Text Articles in Physics

An Experimental Apparatus For Studying Double Differential Scattering By Low-Energy Multiply Charged Ions From Atomic Targets, Meenatchi S. Gopinathan Dec 1994

An Experimental Apparatus For Studying Double Differential Scattering By Low-Energy Multiply Charged Ions From Atomic Targets, Meenatchi S. Gopinathan

Master's Theses

A new differential energy-gain spectrometer with a movable parallel-plate electrostatic energy analyzer has been constructed and tested for the study of double differential (in energy and angle) cross sections for state-selective electron capture processes in collisions of low-energy multiply charged ions with atomic gases. The ion beam is produced by extracting recoil ions from a primary interaction region where these ions are generated in collisions between a neutral target gas and a fast fluorine beam from the WMU tandem Van de Graaff accelerator. An einzel lens is used to focus the ion beam extracted from the recoil-ion source into a ...


Strong Magnetic Field Effects And Molecular Processes With Applications To White Dwarfs, Phillip C. Stancil Jul 1994

Strong Magnetic Field Effects And Molecular Processes With Applications To White Dwarfs, Phillip C. Stancil

Physics Theses & Dissertations

Radiative transitions of hydrogenlike atoms in external magnetic fields of strength applicable to magnetic white dwarfs, i.e. B < 103 megagauss, have been investigated for field-free principal quantum numbers n < 6. Finite proton mass corrections are included. Relativistic corrections are also investigated. Transition probabilities are determined using the length, velocity, and acceleration forms of the electric dipole operator. Discrepancies between previous calculations and magnetic white dwarf observations of low-lying boundbound transitions have been studied. New results for high-lying transitions are also obtained.

The transition probability for the hydrogenlike 2s two-photon decay has been investigated and shown to increase substantially with field strength. The computed two-photon spectra show resonances and interference minima. Anomalous Zeeman depolarization features are found in computed two-photon polarization spectra of alkali atoms in laboratory strength magnetic fields. A previously observed fine structure depolarization feature is shown to decay with decreasing field strength.


Muon Transfer From Muonic Deuterium To Carbon, David William Viel Jan 1994

Muon Transfer From Muonic Deuterium To Carbon, David William Viel

Dissertations, Theses, and Masters Projects

Negative muons were brought to rest in a gas mixture of 30 torr CH$\sb4$ and 570 torr D$\sb2$, using the cyclotron trap at PSI. The muons formed muonic deuterium atoms which diffused through the mixture and transferred their muons to the carbon of the CH$\sb4$ molecules. A planar germanium detector and a silicon detector were used to observe x-rays from the initial muon cascade in the deuterium, and from subsequent cascade in the muonic carbon after transfer. A transfer rate of (4.5 $\pm$ 1.8) $\times$ 10$\sp{10}$/sec was found which agrees well with ...


Collisions Of Atomic Hydrogen With Oxygen, Sulfur, Sodium And Halogen Anions At Low Energies, James Anthony Fedchak Jan 1994

Collisions Of Atomic Hydrogen With Oxygen, Sulfur, Sodium And Halogen Anions At Low Energies, James Anthony Fedchak

Dissertations, Theses, and Masters Projects

Total electron detachment and charge transfer cross sections, $\sigma\sb{\rm e}$(E) and $\sigma\sb{\rm ct}$(E), have been measured for collisions of the negative ions O$\sp{-}$, S$\sp{-}$, F$\sp{-}$, Cl$\sp{-}$, Br$\sp{-}$, I$\sp{-}$, Na$\sp{-}$, and K$\sp{-}$ with atomic hydrogen for laboratory energies ranging from 2 to 500 eV. For the systems F$\sp{-}$, Cl$\sp{-}$, Br$\sp{-}$, O$\sp{-}$ and S$\sp{-}$ + H, $\sigma\sb{\rm e}$(E) displays no barrier for associative detachment; the results are found to be adequately described by simple curve-crossing models based upon available intermolecular potentials ...


Photoabsorption Spectra Of Hydrogen And Alkali Atoms In Electric Fields, Jing Gao Jan 1994

Photoabsorption Spectra Of Hydrogen And Alkali Atoms In Electric Fields, Jing Gao

Dissertations, Theses, and Masters Projects

A systematic study of the photoabsorption spectra of highly excited hydrogen and alkali atoms in electric fields is presented, based on the semiclassical closed-orbit theory. In most respects, hydrogen and alkali atoms behave similarly, because the excited alkali atoms have a single electron outside of a small ionic core, and the core only produces small shifts of energy levels and small phase shifts of scattered wave functions.;For hydrogen, the classical motion of the excited electron is regular and closed orbits can be enumerated. Above the zero-field ionization threshold, the system is rather simple. There is only one closed orbit ...