Thesis (M.S. in Applied Physics)--Naval Postgraduate School, December 2009. / Thesis Advisor(s): Colson, William B. ; Blau, Joseph. "December 2009." Description based on title screen as viewed on January 28, 2010. Author(s) subject terms: Free-electron lasers, FEL simulations, undulators, FEL oscillators, FEL amplifiers, diamond field-emitter arrays, field emission cathodes, cathode test cell. Includes bibliographical references (p. 45). Also available in print.

Thesis (doctoral)--Rupertus Carola University, 2001. / Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 113-124).

Thesis (Ph. D.)--University of Chicago, Department of Chemistry, August 2001. / Includes bibliographical references. Also available on the Internet.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: oxygen consumption; PET; blood flow. Includes bibliographical references (p. 58-61).

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains x, 185 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 132-134).

There are many U.S. health-related standards for ozone that aim to limit exposure to ozone. The potential for ozone emission from electrically connected air cleaners is well- known and has led to standards and regulations for portable indoor air cleaning devices, which emit ozone at measured rates of 0.056 – 13.4 mg/hr. However, there is evidence that some in-duct air cleaners may actually emit more ozone than portable air cleaners, despite being exempt from most regulations due to the lack of a suitable test method for measuring ozone generation. To explore if in-duct cleaners actually do emit ozone, I investigated seven commercially available residential in-duct air cleaning devices. These devices used one of two broad technologies as means of air cleaning: UV light or electrical corona. The lowest measured emission rates came from two air cleaners that utilized UV light technology and were 0.309 ± 1.7 mg/hr, which was likely below the detection limit of the apparatus and method, and 4.29± 1.5 mg/hr. Three of the air cleaners tested, also with UV lamps, were of the same brand and model yet exhibited differing emission rates, ranging from 7.44± 1.6 mg/hr to 15.8± 2.6 mg/hr. These three air cleaners were classified as medium emitters and also utilized UV light technology. The high median measured emission rates were measured from both an air cleaner utilizing electrical corona technology, 30.2 ± 4.0 mg/hr, and UV light technology, 29.4 ± 3.9 mg/hr. These experimental results confirm that some in-duct air cleaners are able to generate more ozone than some portable air cleaners and also suggest potential health risks to the indoor environment. / text

published_or_final_version / Diagnostic Radiology / Master / Master of Philosophy

Secondary electron (SE) emission from thin carbon foils induced by 1-20 keV positrons has been investigated over a range of nominal foil thicknesses from 1.0 to 5.0 μg/cm2. The measurement of SEs was carried out in forward geometry using a microchannel plate as a detector. The SE yield γ has been measured as a function of beam energy and compared with some Monte Carlo simulation results. We also present in this thesis the material parameter Λ=? / (dE / dx) and the emitted SE energy spectra. Forincident positron energy of 5 keV or higher, the distribution is found to be characterizedby the Sickafus form, AEm and m is close to 1. For low energy incident positrons however, another form, Bexp(E / t) , is proposed for describing the SE distribution. The maximum scattering angle for SEs emitted from 5.0 μg/cm2 is found to be around 60°. Measurements of energy loss and energy loss straggling for 1-10 keV positrons passing through thin carbon foils of different thicknesses ranging from 1.0 to 5.0 μg/cm2 are present in this thesis. The stopping power dE / dx and positron transmission coefficient have also been investigated as a function of incident positron energy and foil thickness. Particularly, our experimental results are compared with those from Monte Carlo simulation and theory with a view to providing a way to determine the real thickness of carbon foil. The ratio of the energy loss straggling to the foil thickness seems to have a linear relation with the beam energy. The transmitted positrons after passing through 5.0 μg/cm2 C-foil have a small scattering angle which is less than 10°. Titanium dioxide nanotube arrays fabricated by anodization of titanium foil and annealed at different temperatures were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and positron annihilation spectroscopy (PAS). The crystallization process and morphological change of the nanotubes have been discussed. It is found that anatase (101) only appeared on the walls of the nanotube. The atomic concentration of fluoride and the ratio of Ti/O decreased when the annealing temperature increased. Vacancy type defects were found to diffuse toward the surface when the samples were annealed at 200°C and 400°C and healing of vacancies occurred at 600°C. In addition, the fluoride may form some complexes with vacancies on the surface hence lowering the value of the S parameter. A new design of the lifetime positron beam based on the SE emission is proposed. The observed experimental results and simulation results make it possible to construct a new type of high resolution (<250ps) lifetime positron beam. In addition, how rastering of the positron beam can be used to accurately locate the position of the C-foil is also shown; a feature that will be of value in setting up a positron lifetime system. Such a lifetime system is expected to be much simpler in construction than existing beam based lifetime spectroscopy systems. / published_or_final_version / Physics / Doctoral / Doctor of Philosophy