Activity (A) 1 : The number of nuclear transformations or disintegrations occurring in a quantity of radioactive material per unit time. The SI unit of radioactivity is the becquerel (Bq) (1 disintegration per second)
Ministry of Business, Innovation and Employment, Glossary of terms and acronyms, Wellington, New Zealand 2010. http://wwwsosh.govt.nz/resources/glossary-u.shtml, (Occupn Hlth and Sfty - Brit) {530}