Vernier Software and Technology
Vernier Software & Technology

Counting Statistics


Radioactive decays follow some curious rules that are a consequence of quantum mechanics. Regardless of when a particular nucleus was created, all nuclei of the same species (Cobalt-60 in this experiment) have exactly the same probability of decay. We might expect that the longer a nucleus has been around, the more likely it is to decay, but that is not what is observed. Even though the probability that a given nucleus will decay is fixed, there is no way to predict when it will decay. In this sense the decay process is completely random. Despite this randomness, a collection of many identical and independent nuclei will exhibit certain predictable behaviors, such as a consistent average decay rate when measured over a long time.


In this experiment, you will

  • Use a radiation counter to determine the distribution of count rates from a nearly constantrate source.
  • Compare the distribution of experimental nuclear counting data to the Poisson distribution.
  • Observe the gradual transition of count distribution from Poisson statistics to Gaussian statistics as the average count rate increases.

Sensors and Equipment

This experiment features the following Vernier sensors and equipment.

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Standards Correlations

See all standards correlations for Nuclear Radiation with Vernier »

Experiment 4 from Nuclear Radiation with Vernier Lab Book

<em>Nuclear Radiation with Vernier</em> book cover

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

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