Simulações do ruído de fundo instrumental e reconstrução de imagens do experimento protoMIRAX / Simulations of the instrumental background and image reconstruction of the protoMIRAX experiment

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

In this thesis, the results of detailed and realistic simulations performed with a Monte Carlo simulation code for gamma-ray Astronomy (MGGPOD) to predict the response of protoMIRAX are presented. The protoMIRAX is a project under development by the High Energy Astrophysics group of INPE, in which a hard X-ray camera is being built based on the coded aperture technique using Cadmium-Zinc Telluride (CZT) solid state detectors. The camera is sensitive to X-rays in the energy range from 25 to 200 keV. The experiment will be launched in a balloon and will reach altitudes as high as 40 km for tests and observations of cosmic sources during a ~ 10h flight. This project will be a pathfinder for the MIRAX satellite, a Brazilian project with international partnership, that will put X-ray telescopes into orbit to constantly monitor the central region of the Galatic plane. The simulation results show that the most important contribution to the instrumental background is due to the albedo radiation of the atmosphere in the energy range from Xrays to gamma-rays. The expected counting rate on the CZT detector array in the energy range from 25 to 200 keV is ~ 41 counts/s. This level of instrumental background assures that the protoMIRAX will be able to detect a minimum flux of ~ 2x10^-5 photons/c² s keV from a cosmic point source, considering 5 sigma of statistical significance and 5:5h of integration time in an altitude of ~ 40 km. The main target for observation during the first protoMIRAX flight will be the Crab Nebula and its pulsar. Image simulations obtained by the meridian passage of the Crab Nebula, seen at a latitude of -23°, show a high signal-to-noise ratio of ~ 250. The simulations also show that a Crab image with a level of significance of 10 sigma can be obtained with only 25s of integration. The sensitivity curve obtained shows that the protoMIRAX will be capable of measuring fluxes and spectra from some bright X-ray sources up to ~50 to 80 keV.

ASSUNTO(S)

telescópios de raios x duros simulações simulations ruído de fundo coded masks imageamento máscara codificada x-ray telescopes mggpod imaging background

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