Counts/Interval vs. Distance Studies
The data in the two graphs below were collected by monitoring gamma radiation at various distances from a Radiation Monitor. Data were collected with the run intervals set at 100 seconds. After each 100-second interval, the source was moved one centimeter further from the source. Since distance is proportional to time (300 seconds in the first graph corresponds to 3 cm in the second graph;
400 seconds to 4 cm, etc.), a new distance column was made using time divided by 100. The curved fit shown corresponds to distance raised to the –2 power (inverse squared).
Counts/interval vs. time and distance
Counts/Interval vs. Shielding Studies
The data shown here were collected by monitoring gamma radiation with an increasing number of pieces of silver foil placed between the source and a Radiation Monitor. Data was collected with the run interval set at 100 seconds. After each 100-second interval, another piece of silver foil was placed between the source and the Radiation Monitor. Since the number of pieces is proportional to time (300 seconds corresponds to 3 pieces of foil, 400 seconds to 4 pieces of foil, etc.), a new column, pieces of silver foil, was made using time divided by 100.
Counts/interval vs. thickness of filter
Half-Life Determination (Counts/Interval vs. Time)
Using a daughter isotope generator, it is possible to generate isotopes with a relatively short half-life. A solution that selectively dissolves a short half-life daughter isotope is passed through the generator. The linear plot of natural log of decay rate vs. time can be used to determine the half-life of the daughter isotope, using the formula
ln 2 = λt½
where λ is the decay rate constant and t½ is the half-life of the daughter isotope (in minutes).
In the plot of natural log of decay rate vs. time, the decay rate constant, λ, is equal to –m. Using the slope value of m = –0.217 in the example here, the
half-life was calculated to be 3.19 minutes.
Histogram Data Analysis
For an easy in-class experiment, set up a histogram with a very long run time and start data collection. Whenever the graph overflows the top of the graph, it will be rescaled. This data collection shows students how initial randomness of data develops into a Gaussian distribution. A gamma radiation source was used.
A distribution graph
This graph shows a study of old and new Coleman mantle lanterns. These mantles formerly contained thorium and were often used for radiation demonstrations. In the early 1990s, Coleman changed the production methods and now the mantles are not radioactive. First, no mantle was near the monitor for ten minutes, then an old mantle for ten minutes, and then a new, non-radioactive mantle for the last ten minutes.
New and old lantern mantles
Here is an experiment performed in the days before airlines insisted that you turn off your personal computer before takeoff. It shows the counts/interval between takeoff and the time the plane reached its cruising altitude of 39,000 ft.
Radiation during an airline flight
Nuclear Radiation with Vernier
by John Gastineau
This book has six experiments written for the Vernier Radiation Monitor. Each of the six experiments has a computer version (for LabPro, LabQuest, or LabQuest Mini), a calculator version (for LabPro or CBL 2™), and a LabQuest version (for LabQuest 2 or the original LabQuest as a standalone device). The electronic resources for Nuclear Radiation with Vernier contain the word-processing files for all student experiments.