Daily Variability of Radon Gas in Brazilian Tropics Near Ground Level Surface

Abstract

By monitoring the ionizing radiation from minute to minute in São José dos Campos, SP, Brazil (230 S, 450 W) using Geiger counter, during January to August 2015, it has confirmed the presence of radon gas in these measures. The observation confirms the existence of a periodicity of 24 hours through the technique (Fast Fourier Transform) applied to the data set, and this cycle can be better visible in longer dry periods. On rainy days or with heavy fog in the region, this periodicity is modified or even disappears. As Geiger do not detect alpha particles due to absorption in the walls of the sensor tube, it measured X and gamma rays coming from the radon gas progeny.