“…Namely, radioactive gas radon, with its progenies, which emanates from the soil and construction materials, contributes significantly to the background radiation. In number of experiments where some measurable effects of low-probability process were followed, reduction of background radiation is often most significant way to improve sensitivity (Antanasijević et al, 1999;Dragić et al, 2011;Udovičić et al, 2009;Garcia et al, 1998;Jovancevic and Krmar, 2011).…”