Desenvolvimento da dosimetria termoluminescente e luminescência opticamente estimulada da radiação UV-C
Data
2022-10-14
Autores
Silva, Noemi Aguiar 
Orientadores
Tatumi, Sonia Hatsue
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Foram estudadas duas amostras de óxido de silício, uma sintética e outra natural para aplicação em dosimetria beta e UV-C. O cristal sintético dopado com terras-raras e semi-metais apresentou curvas TL com aumento proporcional quando irradiado com dose beta. Nas medidas de TL, para as doses de 5 a 100 Gy, foram encontrados picos proeminentes em 100 e 350 °C, e outros picos sobrepostos. Na análise com o método Tm - Tstop, foram encontrados cinco picos e com a deconvolução das curvas utilizando o modelo cinético de ordens gerais (GOK) obteve-se valores em 96, 135, 180, 225 e 339 °C (FOM = 4,01%). Para os resultados de TL obtidos após irradiações com UV-C, para diferentes irradiações no UV de 30 até 300 s, sugerem que o pico na temperatura 110 °C cresce conforme a dose. O cristal também apresentou LOE, que cresceu linearmente quando irradiado com dose beta e radiação UV-C. As curvas de CW- LOE e LM- LOE foram deconvoluídas com 3 componentes usando o modelo de GOK. As pastilhas de quartzo verde, apresentaram boa reprodutibilidade em leituras subsequentes de até 7 vezes, não apresentando grandes variações de resposta LOE em função de dose beta, onde 77% delas estavam entre ±σ, o “fading” foi de 10% aproximadamente após 1800 s. Observou-se um crescimento do sinal de LOE quando a amostra foi irradiada com UV-C em diferentes tempos, de 1 até 30 s, podendo ser ajustada com equação exponencial com saturação, obteve-se o R 2 = 0,999. Utilizando a LOE fototransferida foi realizada a dosimetria 2D da superfície de irradiação, com uma dose de 0,201 mGy. Onde foram observadas as curvas de nível da intensidade UV. As pastilhas mostraram capacidade para leitura em menores tempos de exposição utilizando a LOE fototransferida. Considerando os dados obtidos neste estudo, podemos concluir que o quartzo verde e o óxido de silício sintético são promissores para aplicação como dosímetro LOE da radiação beta e UV- C.
Two samples of synthetic and natural silicon oxide were studied for application in beta and UVC dosimetry. The synthetic crystal doped with rareearths and semimetals showed TL glow curves with proportional increase with beta dose. In the TL measurements, for doses from 5 to 100 Gy, prominent peaks were found at 100 and 350 °C, and other overlapping peaks were found. In the analysis with the TM Tstop method, five peaks, using deconvolution method with general kinetic order model (GOK), Tm values were obtained at 96, 135, 180, 225 and 339 °C (FOM = 4.01%). For the TL results obtained after UVC irradiation, with irradiation time of 30 s to 300 s, the peak at temperature 110 °C increased according to the dose. The crystal also showed OSL, which grew linearly when irradiated with beta dose and UVC radiation. The CWOSL and LMOSL curves were deconvoluted with 3 components using GOK model.The green quartz pellets showed good reproducibility in subsequent readings of up to 7 times, they did not show great variations in OSL response as a function of beta dose, where 77% of them were between ±σ, the fading was approximately 10% after 1800 s of storage. An increase in the OSL signal was observed when the sample was irradiated with UVC at different times, from 1 to 30 s, which could be adjusted with an exponential equation with saturation, obtaining an R2 = 0.999. Using the phototransferred OSL, 2D dosimetry was performed, with a dose of 0.201 mGy. Where the UV intensity contour lines were observed. The pellets showed sensibility in shorter exposure times using phototransferred OSL. Considering the data obtained in this study, it can conclude that green quartz and synthetic silicon oxide are promising for application as an OSL dosimeter for beta and UVC radiations
Two samples of synthetic and natural silicon oxide were studied for application in beta and UVC dosimetry. The synthetic crystal doped with rareearths and semimetals showed TL glow curves with proportional increase with beta dose. In the TL measurements, for doses from 5 to 100 Gy, prominent peaks were found at 100 and 350 °C, and other overlapping peaks were found. In the analysis with the TM Tstop method, five peaks, using deconvolution method with general kinetic order model (GOK), Tm values were obtained at 96, 135, 180, 225 and 339 °C (FOM = 4.01%). For the TL results obtained after UVC irradiation, with irradiation time of 30 s to 300 s, the peak at temperature 110 °C increased according to the dose. The crystal also showed OSL, which grew linearly when irradiated with beta dose and UVC radiation. The CWOSL and LMOSL curves were deconvoluted with 3 components using GOK model.The green quartz pellets showed good reproducibility in subsequent readings of up to 7 times, they did not show great variations in OSL response as a function of beta dose, where 77% of them were between ±σ, the fading was approximately 10% after 1800 s of storage. An increase in the OSL signal was observed when the sample was irradiated with UVC at different times, from 1 to 30 s, which could be adjusted with an exponential equation with saturation, obtaining an R2 = 0.999. Using the phototransferred OSL, 2D dosimetry was performed, with a dose of 0.201 mGy. Where the UV intensity contour lines were observed. The pellets showed sensibility in shorter exposure times using phototransferred OSL. Considering the data obtained in this study, it can conclude that green quartz and synthetic silicon oxide are promising for application as an OSL dosimeter for beta and UVC radiations
Descrição
Citação
SILVA, Noemi Aguiar. Desenvolvimento da dosimetria termoluminescente e luminescência opticamente estimulada da radiação UV-C. 2022. 86 f. Dissertação (Mestrado Interdisciplinar em Ciências da Saúde) - Instituto de Saúde e Sociedade, Universidade Federal de São Paulo, Santos, 2022.