Desenvolvimento e fabricação de um protótipo de um dispositivo multiplicador de elétrons à gás micromegas com substrato de silício e isolante SU-8

Abstract

This thesis reports in detail the manufacturing methodology to produce a gas radiation detector which uses a Micromegas electron multiplier, integrated onto a pad readout anode, using a 4” Silicon wafer as a holder. The techniques used to form the wafer micrometric layers are presented and discussed, such as spin coating, photolithography, wet etching, metallization, and development. It describes the improvement in the processing of the insulating material SU-8, as well as in the geometry of the Aluminium mesh holes. Micrographs obtained by Optical Microscope and SEM are presented to analyze the fabricated structure. Simulations with Ansys, Garfield++, and Magboltz software are carried out, to predict the detector response for different gas mixtures. The box assembly and construction projects are reported, and all the components of the detection system and its main properties are presented. Finally, electrical tests are performed with the device, to verify its performance, related to the gain of electrons and energy spectra of the radiation source.The results indicate gains in the order of 3 × 102 for the 241Am and 55F e radioactive sources, and the detection of events due to the irradiation of the 241Am at 13.9 KeV, its main line of energy emission.