This standard radiation test source allows science departments to perform their own GM tube, scaler-timer, ratemeter and Geiger-counter efficiency testing by measuring comparative beta efficiency.
The test source consists of a transparent acrylic slide with a 13mm diameter disc containing 300mg of Potassium chloride, which is a naturally occurring radioactive compound due to the presence of 0.0117% of Potassium-40 (K-40).
Due to the extremely low activity of Potassium compounds, the test source is not classed as a radioactive source, and does not need to be labelled or treated as such.
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