A fast-slow coincidence setup for reproduction of the unit radionuclide activity in the 105 to 109 Bq range

Advances in nuclear power engineering, new technologies, medical tomography, etc., employing highly active radionuclide sources of ionizing radiation demand absolute measurements of the activity of radionuclides in the 105 to 109 Bq range. To solve this problem, the author has developed and built a standard fast-slow coincidence setup as part of the national primary standard of the unit of activity of radionuclides. In this work, he discusses the main principles of setup design and a new approach to activity measurement using time coincidences of nuclear particles -- alpha particles, photons, x-ray photons, Auger electrons, and shock electrons originating in disintegration of radioactive nuclei. 3 refs., 2 figs