Page 199 - Radiation Safety

• Half life - time for activity of radionuclide to reduce by half

• Ranges from very short to very long

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e.g. U-235 (7.13 x 10 y), N-16 (7.13 s)

• Activity at time t , A(t)

A = A(0) exp(-l t )
t
l = ln(2)/T 1/2  0.6931/ T 1/2 (decay constant)

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