While different isotopes have different half-lives,<ref>Avison J. ''The World of Physics''; Thomas Nelson and Sons; Cheltenham. p. 395, (1984) [http://books.google.com/books?id=DojwZzKAvN8C&lpg=PA395&dq=%22short%20half-life%22&pg=PA395#v=onepage&q=%22short%20half-life%22&f=false]</ref> some being very short and difficult for scientists to study, the concept is a useful one for measuring and comparing the decay rates of different isotopes.
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While different isotopes have different half-lives,<ref>Avison J. ''The World of Physics''; Thomas Nelson and Sons; Cheltenham. p. 395, (1984) [https://books.google.com/books?id=DojwZzKAvN8C&lpg=PA395&dq=%22short%20half-life%22&pg=PA395#v=onepage&q=%22short%20half-life%22&f=false]</ref> some being very short and difficult for scientists to study, the concept is a useful one for measuring and comparing the decay rates of different isotopes.