Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 116-121). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 103-110). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 116-121). Also available on the Internet.

Thesis (Ph. D.)--University of Canterbury, 2010. / Typescript (photocopy). Includes bibliographical references (p. 196-206). Also available via the World Wide Web.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xxii, 212 p.; also includes graphics. Includes bibliographical references (p. 203-212). Available online via OhioLINK's ETD Center

Thesis (Ph.D.)--Ohio University, August, 2003. / Title from PDF t.p. Includes bibliographical references (leaves 188-194)

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

The High Radiation to Materials facility employs a high intensity pulsed beam imposing several challenges on the beam position monitors. Diamond has been shown to be a resilient material with its radiation hardness and mechanical strength, while it is also simple due to its wide bandgap removing the need for doping. A new type of diamond based beam position monitor has been constructed, which includes a hole in the center of the diamond where the majority of the beam is intended to pass through. This increases the longevity of the detectors as well as allowing them to be used for high intensity beams. The purpose of this thesis is to evaluate the performance of the detectors in the High Radiation to Materials facility for various beam parameters, involving differences in position, size, bunch intensity and bunch number. A prestudy consisting of calibration of the detectors using single incident particles is also presented. The detectors are shown to work as intended after a recalibration of the algorithm, albeit with a slightly lower precision than requested, giving a promising new beam position monitoring system. They work for the full intensity range and a single bunch resolution is achieved. Functionality is also shown with backscattering from dense targets.

O presente trabalho estuda a produção e modificações físico-químicas do grafeno frente a tratamentos térmicos. Em uma primeira etapa, foi investigada a síntese de grafeno pela técnica de Deposição Química a partir da fase Vapor (CVD) sobre fitas de cobre. Nós variamos quatro parâmetros que influenciam no crescimento de grafeno: fluxo de metano (CH4), fluxo de hidrogênio (H2), tempo de crescimento e grau de pureza do cobre. Usando as técnicas de caracterização de espectroscopia Raman e microscopia óptica, observamos que fluxo menor de H2 e fluxo intermediários de CH4 favorecem o crescimento de grafeno de alta qualidade. Além disso, vimos que 15 minutos de crescimento de grafeno é suficiente para cobertura do substrato de cobre com grafeno. Por fim, foi visto que o maior grau de pureza do cobre permite a produção de monocamadas de grafeno mais homogêneas. Numa segunda etapa, foi realizado um estudo com objetivo de entender a interação de hidrogênio com monocamadas de grafeno. Nós usamos amostras de grafeno depositadas em filmes de SiO2 (285 nm)/Si e tratadas termicamente em atmosfera controlada de deutério (99,8%) em temperaturas entre 200 e 800 °C. Nós também investigamos a dessorção de hidrogênio do grafeno usando amostras previamente tratadas em deutério a 600 °C e depois tratadas em atmosfera controlada de nitrogênio em temperaturas entre 200 e 800 °C. Após os tratamentos, análise por reação nuclear (NRA) foi realizada para quantificar o deutério, onde nós observamos uma grande incorporação de deutério no grafeno acima de 400 °C, tendo um aumento moderado até 800 °C. Nós também observamos que a dessorção do deutério do grafeno ocorre apenas em 800 °C, embora a dessorção de deutério do óxido de silício ocorra a partir de 600°C. Espectroscopia Raman também foi realizada após cada tratamento térmico. Os resultados mostram que os defeitos na estrutura do grafeno têm um grande aumento para as etapas de maior temperatura na incorporação de deutério. Análises realizadas com Espectroscopia de Fotoelétrons Induzidos por Raios X (XPS) mostraram que a incorporação de deutério para maiores temperaturas causa o "etching" do grafeno. Por fim, caracterizações usando Espectroscopia de Absorção de Raios X (NEXAFS) mostraram que o deutério liga-se ao grafeno sem orientação preferencial. / The present work studies the production and physical-chemical modifications of the graphene under thermal annealings. In a first study, the graphene synthesis by Chemical Vapor Deposition (CVD) on copper foils was investigated. We varied four parameters that influence the growth of graphene: methane flow (CH4), hydrogen flow (H2), growth time and copper purity. Using Raman spectroscopy and optical microscopy, we observed that lower flux of H2 and intermediate flux of CH4 leads to the growth of high quality graphene. In addition, we observed that 15 minutes growth of graphene is sufficient to cover the copper substrate. A higher copper purity allows the production of homogeneous graphene monolayers. In a second step, a study was carried out to understand the interaction of hydrogen with graphene monolayers. We used graphene samples deposited on SiO2 (285 nm)/Si films and annealed in a controlled atmosphere of deuterium (99.8%) at temperatures between 200 and 800 °C. We also investigated the hydrogen desorption of graphene using samples previously treated in deuterium at 600 °C and then annealed in a controlled atmosphere of nitrogen at temperatures between 200 and 800 °C. After the annealings, nuclear reaction analysis (NRA) was performed to quantify the deuterium, where we observed a large incorporation of deuterium in graphene above 400 °C, with a moderate increase up to 800 °C. We also observed that desorption of deuterium occurs only at 800 °C, although deuterium desorption from silicon oxide occurs at 600 °C. Raman spectroscopy was also performed after each annealing. The results show that defects in the structure of graphene have a large increase for deuterium incorporation. Analyzes carried out with X-ray Photoelectron Spectroscopy (XPS) showed that the deuterium incorporation at higher temperatures leads to graphene etching. Finally, characterizations using X-ray Absorption Spectroscopy (NEXAFS) showed that deuterium binds to graphene without preferential orientation.