Pre-Lab 13 Assignment: Radioactive Decay

Radioactive Decay v 0.1
Question 2.6 Are your values from the second run in agreement with the ones obtained in the
first run? If not determine the possible source of errors.
Question 2.7 The sample you used is of 137
56Ba. The accepted value of its half-life is about 156
seconds. Compare your measured results with the results obtained in the lab. Roughly estimate
the error in your estimate of the half-life. Are your results in agreement (within error bars)
with the accepted value? If not, determine the possible sources of errors.
Question 2.8 What modifications in the described procedure could lead to smaller errors in
the determination of the half-life? Explain your answer.
Investigation 3:
Background Radiation
As noted in Investigation 2 the best fit to your experimental data was one where the activity
did not go to zero as t → ∞. This is due to what is called background radiation, which is
radiation that we are exposed to everyday. The sources of this radiation are cosmic rays as
well as sources from our soil such as radon gas. This background radiation will change from
one place to another. However, if no other artificial sources are brought to a given site the
background radiation on that site should be nearly constant. In this activity we will measure
the background radiation in our lab and compare to the values we determined in investigation
2.
For the activities in this investigation you will need:
• computer-based laboratory system
• experiment configuration files
• radioactivity probe
PHYS-204:Physics II Laboratory 8