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Radioactive Decay: Half Life T
1/2
The time needed
for half of the radionuclides to decay
, or equivalently the activity of
a sample to be reduced to half its initial value, is called
half life, T
1/2
:
λ
=
⇒ λ−
=
2ln
T
) T ( exp N
2
N
2/1
2/1
0
0
or equivalently
) T ( exp A
2
A
) T(A
2/1
0
0
2/1
λ−
= =