This is the eighth semiannual report on Physics and Health Sciences at the Canadian TASCC facility. Very gratifying progress has been made in commissioning the superconducting cyclotron of the TASCC facility. The number of beams available at the end of the year was 17, of which 12 were developed during 1989. Of particular importance was the acceleration for the first time ever of a beam with the radio frequency system operating in the mode. Members of the Radiation Biology and Dosimetric Research Branches have just completed a 5-year experiment on the relative biological effectiveness of tritium rays in a mammalian tumor system and the induction of acute myeloid leukemia in mice. This is of considerable importance in Canada, because an appreciable portion of the dose from operation of CANDU nuclear electricity generation comes from this radionuclide.
