257 leaves : ill. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics, 1970

Thesis (Ph.D.) -- University of Adelaide, Dept. of Physics, 1970.

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 110-113).

by Kwok Si Ho. / Chinese title in romanization: Re shi guang duan dai xi tong zhi zhi zao ji re shi guang zhi yi xie te xing you jian ji liang duan dai fa zhi yan jiu. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1988. / Bibliography: leaves 98-101.

The kinetic and dosimetric features of the main thermoluminescence peak of quartz have been investigated in unannealed as well in quartz annealed at 500˚C for 10 minutes. The main peak is found at 92 and 86˚C respectively for aliquots of unannealed and annealed samples irradiated to 10 Gy and heated at 5.0˚C/s. For each sample, the intensity of the main peak is enhanced with repetitive measurement whereas its maximum temperature is unaffected. The peak position of the main peak in each sample is independent of the irradiation dose and this, together with its fading characteristics are consistent with first-order kinetics. For low doses, typically between 2 and 10 Gy, the dose response of the main peak in each sample is linear. In the intermediate dose range from 10 to 60 Gy, the growth of the main peak in each sample is sub-linear and for greater doses, in the range from 60 Gy to 151 Gy, it is linear again. The half-life of the main peak of the unannealed sample is about 1.3 h whereas that of the annealed sample is about 1.2 h. The main peak in each sample can be approximated to a first-order glow peak. As the heating rate increases, the intensity of the main peak in each sample decreases. This is evidence of thermal quenching. The main peak in each sample is the only peak regenerated by phototransfer. The resulting phototransferred peak occurs at the same temperature as the original peak and has similar kinetic and dosimetric features. For a preheat temperature of 120˚C, the intensity of the phototransferred peak in each sample increases with illumination time up to a maximum and decreases afterwards. At longer illumination times (such as 30 min up to 1 h), no further decrease in the intensity of the phototransferred peak is observed. The traps associated with the 325˚C peak are the main source of the electrons responsible for the regenerated peak. Radioluminescence emission spectra were also measured for quartz annealed at various temperatures. Emission bands in quartz are affected by annealing and irradiation. A strong enhancement of the 3.4 eV (~366 nm) emission band is observed in quartz annealed at 500˚C. A new emission band which grows with annealing up to 1000˚C is observed at 3.7 eV (~330 nm) for quartz annealed at 600˚C. An attempt has been made to correlate the changes in radioluminescence emission spectra due to annealing with the influence of annealing on luminescence lifetimes in quartz.

No description available.

No description available.

No description available.

Desenvolveu-se um sistema termoluminescente especial, para operar a partir da temperatura do nitrogênio líquido, que permite, ainda, a obtenção do espectro de emissão termoluminescente da amostra. Com o uso deste sistema, estudou-se a termoluminescência do LiF:Mg,Ti (TLD-100), irradiado a 77 K, desde a temperatura de irradiação até 315K. Neste intervalo de temperaturas foram determinados sete picos de emissão termoluminescente em 139, 153, 194, 240, 260, 283 e 300K. Através de experiências de variação do tratamento térmico da amostra, linearidade, fototransferência e destruição óptica, o pico de emissão termoluminescente em 139K foi associado a centros de buracos Vk, enquanto que os demais a armadilhas de elétrons. Os sete picos de emissão termoluminescente emitem em três comprimentos de onda, 270, 300 e 420nm, sendo que a banda de emissão em 270nm é a mais intensa no caso dos picos de emissão termoluminescente em 139 e 153K, sobressaindo-se as bandas de emissão em 300 e 420nm para os demais picos de emissão termoluminescente. A banda de emissão em 270nm foi associada a centros de recombinação para buracos liberados dos centros Vk, centros estes diferentes daqueles, normalmente, associados à banda de emissão em 420nm. Quanto à banda de emissão em 300nm, esta foi associada à interação entre elétrons e centros Vk. Verificou-se que os picos de emissão termoluminescente em 139, 153, 194 e 260K obedecem à cinética de primeira ordem. As energias de ativação determinadas para estes picos foram, respectivamente, 0,26, 0,29, 0,49 e 0,82eV. / A special thermoluminescent system was deve1oped. It is able to operate right from liquid nitrogen temperature and also permits the determination of the sample thermoluminescent emission spectrum. Using this system, the thermoluminescence displayed by 77K irradiated LiF:Mg,Ti (TLD-100), from the irradiation temperature to 315 K, was studied. In this temperature range seven glow peaks, at 139, 153, 194, 240, 260, 283 and 300 K, were determined. Based upon different annealing procedures, linearity, phototransference and optical bleaching experiments, the glow peak at 139 K was related to Vk hole centres, while the remaining glow peaks were associated to electron traps. The seven glow peaks emit at three wavelengths, namely, 270, 300 and 420 nm. The emission band at 270 nm is the most intense in the case of glow peaks at 139 and 153 K. For the remaining glow peaks, the emission bands at 300 and 420 nm are the most important ones. The emission band at 270 nm was related to the recombination of Vk holes at recombination centres other than those ones, normally, associated to the emission band at 420 nm. The emission band at 300 nm was related to the recombination of electrons and Vk centres. It was verified that the glow peaks at 139, 153, 194 and 260 K obey the first order kinetics. For these glow peaks, the determined activation energies were, respectively, 0,26, 0,29, 0,49 and 0,82 eV.

by Ngar Yuen Kan. / Title also in Chinese. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 117-118.