Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 8 of 8
Full-Text Articles in Physics
Collisions Of Atomic Hydrogen With Oxygen, Sulfur, Sodium And Halogen Anions At Low Energies, James Anthony Fedchak
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, or by classical orbiting models which assume that the anion interacts with the H atom via an attractive potential of the …
Photoabsorption Spectra Of Hydrogen And Alkali Atoms In Electric Fields, Jing Gao
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, called …
Models For Water Outgassing From Metal Surfaces, Minxu Li
Models For Water Outgassing From Metal Surfaces, Minxu Li
Dissertations, Theses, and Masters Projects
In this study, the outgassing rate from an electropolished stainless steel surface following exposures to H{dollar}\sb2{dollar}O vapor under various conditions was measured. The results of the experiments showed that the outgassing rate is proportional to {dollar}p\sb0\sp{lcub}n{rcub}{dollar}, where {dollar}p\sb0{dollar} is the H{dollar}\sb2{dollar}O exposure pressure and n is about 0.25. The outgassing rate is not as strongly dependent on the system temperature as one would expect if the temperature is kept the same during exposure and pump-down. The outgassing rate is also a function of the exposure time for the first several hours of exposure, indicating that the adsorption saturation time is …
Glueball Wave Functions And Production Cross Sections, Anthony B. Wakely
Glueball Wave Functions And Production Cross Sections, Anthony B. Wakely
Dissertations, Theses, and Masters Projects
Three topics are studied in this dissertation.;Using QCD sum rules, I first calculate the first few moments of the distribution amplitude of the pseudoscalar glueball, a bound state of gluons. The distribution amplitude is the momentum wave function integrated over the transverse momentum. QCD sum rules are a method of finding hadronic parameters using perturbative QCD. I use an approximation in which the glueball is treated as a narrow resonance. The moments of the distribution amplitude then give the corresponding first few coefficients of the distribution amplitude for the glueball expanded in Gegenbauer polynomials. The distribution amplitude is rather close …
A Relativistic Model Of Pion Nucleon Scattering And Pion Photoproduction On A Single Nucleon, Yohanes Surya
A Relativistic Model Of Pion Nucleon Scattering And Pion Photoproduction On A Single Nucleon, Yohanes Surya
Dissertations, Theses, and Masters Projects
Pion nucleon scattering is described by a manifestly covariant wave equation in which the pion is restricted to its mass-shell. The kernel of the equation includes nucleon (N), Roper (N*), delta ({dollar}\Delta{dollar}) and {dollar}D\sb{lcub}13{rcub}{dollar} poles, with their corresponding crossed pole terms approximated by contact interactions, and contact {dollar}\sigma{dollar}- and {dollar}\rho{dollar}-like exchange terms. The {dollar}\pi NN{dollar} vertex is treated as a mixture of {dollar}\gamma\sp5{dollar} and {dollar}\gamma\sp\mu\gamma\sp5{dollar} coupling, with a mixing parameter {dollar}\lambda{dollar} chosen so that the dressed nucleon pole will be unshifted by the interaction. Chiral symmetry is maintained at threshold. The resonance contributions are fully unitarized by the equation, with …
Polarization Transfer Coefficient Measurements In The Deuteron Breakup Reaction Hydrogen-1(Polarized Deuteron,Polarized Proton)X At 2.1 Gev, Naipor Eric Cheung
Polarization Transfer Coefficient Measurements In The Deuteron Breakup Reaction Hydrogen-1(Polarized Deuteron,Polarized Proton)X At 2.1 Gev, Naipor Eric Cheung
Dissertations, Theses, and Masters Projects
The polarization of the protons emerging at 0$\sp\circ$ from the inclusive deuteron breakup reaction $\sp1$H($\vec d,\vec p$)X was measured using a deuteron beam with kinetic energy of 2.1 GeV. The momentum of the protons was selected by the magnetic spectrometer SPES4 and the polarization was measured with the polarimeter POMME. This experiment was performed at eight different proton momenta. When those momenta are Lorentz transformed to the deuteron rest frame, they corresponded to values from 0.00 to 0.34 GeV/c. The result of the measurements is expressed in terms of polarization transfer coefficient which is defined as the ratio of the …
Low Internal Magnetic Fields In Anisotropic Superconductors, Allan J. Greer Jr.
Low Internal Magnetic Fields In Anisotropic Superconductors, Allan J. Greer Jr.
Dissertations, Theses, and Masters Projects
This thesis is a theoretical, numerical study of the magnetic fields which exist in the anisotropic, high temperature superconductors like $YBa\sb2Cu\sb3O\sb{7-\delta}$, or YBCO for short, using both the anisotropic London theory and simulations based on existing muon spin rotation techniques. The thesis first describes the muon spin rotation ($\mu$SR) techniques, and then gives a brief discussion of superconductivity with regard to the London theory of anisotropic, type II superconductors. Next, numerical results of the application of this theory to YBCO are presented. Three dimensional surface plots of the magnetic field components within the flux line lattice (FLL) are shown, as …
Muon Transfer From Muonic Deuterium To Carbon, David William Viel
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 a previous result measured at 50 bar of …