Physlet Illustration: Radioactive Decay

 

 
In this simulation, a source of decaying nuclei is placed near a detector.  Since the activity is directly related to the number of decaying nuclei the graph of activity versus time is also a graph of remaining nuclei as a function of time.  From the graph determine the half-life of the radioactive nuclei in the source.

Hints:

  1. Determine the initial activity by reading off of the graph.
  2. How long does it take for the activity to decrease to one-half the initial value?
  3. Measure the decay constant from the graph.  It is the time for the activity to decrease by 1/e.
  4. How is the half-life calculated from the decay constant?

 

Reference

See Walker, Sections 32-3

Illustration written by Mario Belloni and Chuck Niederriter