Gamma ray contribution to the ambient dose rate in the city of Sao Paulo, Brazil

摘要

The gamma contribution to the dose received by the population in the city of Sao Paulo, Brazil, was evaluated. Gamma ray spectroscopy with a sodium iodide scintillation detector was chosen as the technique, by the easiness of use, high sensitivity and possibility of identification of an inadvertent contamination. Measurements were taken at I m from the ground, outdoors (at the streets) and indoors (at commercial places). Besides the gamma spectra, the ambient dose equivalent rates were assessed. It was found that in average the indoor dose rates are 46% higher than the outdoor values. No statistically significant cluster of dose values was found in the distribution of outdoor values over the city territory, although a non-homogeneous pattern is observed. As far as the indoor sample is concerned, the statistical analysis points to different mean values, according to the category of the commerce. A final conclusion is that the ambient dose equivalent values observed are high when compared to other places of the world. (C) 2003 Elsevier Ltd. All rights reserved. [References: 16]