Polonium
Polonium is the chemical element with atomic number 84. It was discovered 1898 by Marie and Pierre Curie and named after Marie's native country Poland. Natural Polonium is found in uranium ores. Polonium can also be generated artificially by particle bombardment in nuclear reactions. Like all isotopes of Polonium the nuclide Po-210 is radioactive and has a half-life of 138 days. It emits alpha particles with an energy of 5.3 MeV. The yield of more penetrating gamma rays is negligible. In dense matter alpha particles are depositing large amounts of energy and the particles are stopped within very short distance. In tissue their range is below 0.1 mm. The range of alpha particles in air is a few cm. Alpha radiation can easily be shielded even by a piece of paper. Therefore, for humans there is only real danger if Po-210 is incorporated in the body. If a Po-210 source is outside the body, there would be no danger, because the alpha particles wouldn't be able to penetrate clothing or the skin.

Detection of Po-210 Contaminations
Contamination with Po-210 on surfaces can easily be detected by using a handheld contamination monitor capable of alpha particle detection. Berthold Technologies offers the LB 124 SCINT contamination monitor for this purpose. This instrument has a low weight and a high efficiency for the detection of alpha particles. It's sensitive detection area is 170 cm². The minimum detectable amounts (MDA) of Po-210 contamination depends on the measuring time and also on the background measuring time. This is because radioactive decay is a statistical process. The minimum detectable Po-210 contamination measured with a detector of 170 cm² is shown in the diagrams on the right side. These values were calculated according to ISO 11 929-1 and ISO 7503-1 assuming error probabilities of 5 % and background measuring time 200 s. Even extremely low contamination levels can be detected and measured quickly and reliably with this device.