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.	2010 Summer Professional Development School Internal Dosimetry 23 - 26 June 2010 Idaho State University, Pocatello, Idaho
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18 March 2010

Half-life

The time in which one-half of the activity of a particular radioactive substance is lost due to radioactive decay. Measured half-lives vary from millionths of a second to billions of years. Also called physical or radiological half-life.