Energy sensitive and large area X-ray fluorescence imaging system based on GEM detectors

• Autor(a) principal: Souza, Geovane Grossi Araújo de
• Data de Publicação: 2023
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/43/43134/tde-07082023-064922/
• topic: Detectores de radiação; Detectores do tipo GEM; Detectores gasosos baseados em micro-estruturas; Eletrônica de leitura.; Gas Electron Multiplier; Imagem de fluorescência de raios-x; Micropattern gaseous detectors; Radiation detectors; Readout electronics.; X-ray fluorescence imaging

This work consists in the assembly, study, and characterization of a large area, position sensitive, and energy dispersive X-ray gaseous detector based on GEMs (Gas Electron Multiplier), optimized to operate in the energy range from 1keV to 30keV. The advantage of using such large detectors is to reconstruct images without the need to scan the sample. These detectors are cost effective when compared to solid state devices, they can reach high gains using multiple multiplication structures and, with a suitable readout electronics, it is possible to work at high counting rates. Moreover, handling these detectors is relatively simple since they can work without flammable or toxic gases and, by making small changes in their assembly, it is possible to detect different types of radiation. The construction of a detector that operates in this energy range is interesting to the scientific community because it may assist research from different areas with position sensitive X-ray fluorescence imaging. Exploiting this technique it is possible to detect the presence of different chemical elements and to obtain their spatial distribution in a sample. Cultural heritage studies can be performed using this technology and also this equipment can be implemented in different fields such as industry, crystallography and nuclear safety and security. In this work, the SAMPA chip was integrated in CERN\'s Scalable Readout System to collect the signals produced by the detector. Software tools for acquisition control, data acquisition, and the reconstruction of images and spectra were also developed. To test this new system a thin-gap detector for 1-D X-ray imaging and fluorescence, and also on a small Time Projection Chamber for cosmic ray detection were build. Along with the experimental results, a set of simulations were made in order to adapt and optimize this type of detectors, initially developed for high energy physics, to low energy applications such as X-ray imaging and fluorescence.