PHY222, Elements of Physics II
Radioactive Half-Life, 18 April 2008

Note on Purpose:
Lazy clones of the lab manual = lab report in terlet.

Theory Requirements:

1. Describe the three kinds of radioactive decay. Provide an example and "chemical equation" for each, and identify which kind is observed in the lab.
2. Look up and describe an application of radioactive decay or radioactive isotope studies.
3. State the value we expect to measure for the Barium half-life, T, and its relationship to our experimental parameters.

Comments on the Procedure:
As usual, summarize the major steps in the procedure - make an effort to avoid tangents. Do not blindly refer to a figure in the lab manual - where appropriate, give a brief description (such as wire placement, whatever will help you).

The key feature to note in your report is, as always, what should be measured, and how you do it.

Manual Error: There are references in the manual to a "START rocker switch" throughout the procedure, especially in the Preliminary Preparation section. The switch is actually labeled COUNT.

Comments on Data:
DESCRIBE THE DATA TABLES and/or GRAPHS YOU PRESENT. This requires barely a sentence to state what the reader gets to find in each table or graph. Consider it some small evidence that you have some idea of what you were measuring and recording.

Results Checklist:

• Half-life measurement, its uncertainty from LINEST (see next point), and the percent difference comparing your measurement of the half-life to the real value.
• ***Because we have to use a formula to relate the slope of our graph to the half-life measurement, there is an analogous formula that relates the slope uncertainty to the actual half-life uncertainty.
  

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  half-life uncertainty = (slope uncertainty)*(ln 2) / (slope^2)
  

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• Sample calculation: obtaining the half-life from the slope.
• Sample calculation: obtaining the half-life uncertainty from the slope uncertainty.

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