Construcción de un prototipo de detector de radiación ambiental con centelladores plásticos.

Abstract

The objective of this research was the construction of a prototype environmental radiation detector using plastic scintillators, which coupled a plastic scintillator of dimensions 25x25x1cm, a Silicon photomultiplier (SiPM) and a data acquisition system (DAQ-FPGA). The device was placed inside a dark box that isolated it from outside light in contact with the radioactive source (241Am, 90Sr, and 137Cs) and was tested for one and two scintillator blades. The acquisition and analysis of the information were done through two different systems, the first by direct acquisition of an oscilloscope, the generated files were analyzed in Matlab using the findpeak function, which showed information about the shape of the pulses and their amplitudes and widths; presented in histograms voltage-number of pulses. The second used a QuarkNet developed by Femilab, which does, which makes use of the time-to-digital coverter (TDC) and the coincidences between events recorded in a time window of 1000ns, through which the data of the recorded pulses are generated in a DAT file that analyzed by ROOT allowing obtaining histograms of front and back edge of the detected pulse, TDC_LE and TDC_TE respectively, their difference allowed to know the time-to-over-thershold (ToT), that is to say the time it lasts pulse determined over a threshold voltage, which in this investigation was 30 mV. The analyzed data show that both systems, when the scintillator is in contact with a source of 241Am, the differences in the distributions of the voltages or the ToT, referring to the ones obtained for the palette without source are very similar, while for the sources of 90Sr and 137Cs, there are slight differences, almost imperceptible; therefore, the use of plastic scintillators with a thickness of less than 1 cm is recommended for future research.