Due to the presence of the natural radionuclides

Abstract

For qualitative identification as well as quantitative determination of the specific activity of gamma-emitting radionuclides present in tobacco samples, a high-resolution gamma-ray spectrometer equipped with a planar BEGe (Broad Energy Germanium) detector (Canberra, model BE 3825) was used. The system has a relative efficiency of 20% and an energy resolution (FWHM) of 0.38 keV at 5.9 keV, 0.628 keV at 122 keV and 1.724 keV at 1332.5 keV. The detec- tor was connected to a Digital Signal Analyser (DSA-LX) Unit (16K channel signal analyser, V1.0) from Canberra. It is shielded with 15 cm of lead (including 2 cm made of archae- ological lead) to reduce the contribution of environmental radioactivity to its background. The lead shielding was sur- rounded with an inner layer of copper (0.2 cm thick) toreduce the contribution from Pb X-rays.