Half Life

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• The time it takes for $1/2$ of a sample of a given radionuclide to undergo decay
• Ways of measuring
  • Number of nuclides (nuclides/time)
  • Mass of radioisotopes

$N_1=N_0\times (\frac{1}{2}{)}^x$

• where x is the number of half lives it has undergone, and $N_1$ and $N_0$ are the final and original amounts of the substance, respectively

Number of half lives that have been undergone:

$\frac{\log (\frac{N_1}{N_0})}{\log \frac{1}{2}}$ Number of years that have passed

$\frac{\log (\frac{N_1}{N_0})}{\log \frac{1}{2}}\times halflife$