Estudo da resposta de monitores de radioproteção em feixes padronizados de radiação X, gama e beta.

Abstract

The response of 76 Geiger-Muller detectors, 4 semiconductor detectors and 34 ionization chambers were studied. Many of them were calibrated with gamma radiation beams (Cs and Co), and some of them were tested in beta radiation (Sr+Y e Tl) and X radiation (N-60, N-80, N-100, N-150) beams. For all three types of radiation, the calibration factors of the instruments were obtained, and the energy and angular dependences were studied. For beta and gamma radiation, the angular dependence was studied for incident radiation angles of 0 and ± 45. The curves of the response of the instruments were obtained over an angle interval of 0 to ± 90, for gamma, beta and X radiations. The calibration factors obtained for beta radiation were compared to those obtained for gamma radiation. For gamma radiation, 24 of the 66 tested Geiger-Muller detectors presented results for the energy dependence according to international recommendation of ISO 4037-2 and 56 were in accordance with the Brazilian ABNT 10011 recommendation. The ionization chambers and semiconductors were in accordance to national and international recommendations. All instruments showed angular dependence less than 40%. For beta radiation, the instruments showed unsatisfactory results for the energy dependence and angular dependence; For X radiation, the ionization chambers presented results for energy dependence according to the national recommendation, and the angular dependence was less than 40%.