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>Thesis. The modeling of the Ames Laboratory Research Reactor core region and the input required to utilize the Monte Carlo computer code KENO for criticality calculations are described. Reactivity calculations in terms of k- effective were made for various reactor configurations and compared to measurements made on the actual reactor. (16 references) (auth)

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Thesis. Submitted by J. Lorrain. Theoretical analyses of interphase processes involving vapors and liquids are presented. Monoatomic and reacting vapors were considered in situations such as condensation, evaporation and heat transfer between the vapor and its liquid. These developments are believed to be the most accurate to date in describing such processes. The implications of the presence of diatomic and heavier naolecules in liquid metal vapors in their condensation heat transfer are discussed. It is shown that some assumed detailed mechanisms of condensation of these species can explain the low experimental condensation heat transfer coefficients of liquid metals. Results of an experimental investigation of the condensation mechanism and condensation heat transfer of nitrogen tetroxide vapor are presented. From measurements of temperature profiles in the vapor near the vapor-llquid interface during condensation it was concluded that both major components of the vapor (nitrogen dioxide and nitrogen tetroxide) condense at comparable rates. This mechanism is in qualitative agreement with the experimental condensation heat transfer coefficients, which were found to be 10 to 20% higher than predicted by Nusselt's theory. This is apparentiy the first determination of a detailed condensation mechanism at moderate pressures where traditional methods (e.g., vacuum evaporation techniques) can not …

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Thesis. The optical absorption spectra of Ho/sup 3+/ in the rare earth salt HoF/sub 3/ is studied. Such optical region studies (visible radiation) are easily performed with standard light sources and optical arrangements. Since the energy range of visible light coincides with the excitation energy range for a number of electronic transitions within the rare earth salts, the studies theoretically provide considerable information about rare earth electronic energy levels. Data are compiled for the effects of an applied magnetic field upon the spectra and the effect of sample temperature on the observed absorption spectra. 61 references. (MCW)

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Thesis. The specific heat was measured from 2.55 to 15.7 deg K, first with no external magnetic field, and then with magnetic fields along the c-axis and a-axis of intensity of 1000, 3000, and 5800 Oe. Two specific heat anomalies were observed: a Schottky anomaly caused by the ground state exchange splitting of the Yb/sup 3+/, and spin reorientation of the Fe sublattice. (DLC)