Desenvolvimento de um sistema de detecção de radiaçãoionizante usando um fotodiodo SiPIN

Abstract

In this work the development of an instant dose rate measurement system and X-ray, gamaand beta measurements using a SiPIN semiconductor in an integrated RD2007 module was presented. The work focuses on the description of the different elements present in a SiPIN photodiode detection system, such as SiPIN photodiode technology, charge integrators, pulse amplifiers and amplifiers, and TTL output discriminators. The work is a counterpart to the understanding of ionizing radiation detection systems using solid state detectors, since the problems of pulse resolution, pulse storage, noise sourcesand calibration are elucidated. In this work a comparison was also made between the solution implemented with the RD2007 integrated module and the gas detection technologies. For this purpose an additional calibrated Geiger-Muller gas detector was used. The main interest is to compare the solid state detection technology based on SiPIN photodiodes and Geiger-Muller detectors. The work also focuses on elucidating good handling practices in dealing with electronic circuits. Such practices are imperative for the manipulation of high-performanceelectronic components and printed circuit boardsproduction, providing a proper understanding of the effects of static energy on electronic components using field-effect transistors (JFET and CMOS) technology. The latter are the most common choice for the implementation of CR-RC analogue networks and preamplifiers because they have bandwidths generally superior to their peers manufactured with bipolar junction transistors as well as very low bias current, which contribute to the non-saturation at the output of the preamplifiers implemented with operational amplifiers and the possibility of high transimpedance gains. The very high transimpedance gains are necessary when detecting charges generated in the photodiodes when the radiation ionization, because these are really small. The work also addressed the programming and use of a microcontroller with wifi interface as a means of computing digital pulses emerging from a CMOS logic port and creating an Internet server embedded in the microcontroller for measuring radioactive sources at safe distances. The obtained results showed that the developed system of radiation detection based on a SiPIN semiconductor presented good performance in relation to the gas detectors.