Well counter

A well counter is a device used for measuring radioactivity in small samples.

It usually employs a sodium iodide crystal detector.

[2] The well counter is so called because the samples are inserted into a well within the crystal in order to maximize sensitivity by collecting as many of the emitted gamma rays as possible.

Modern well counters can automatically record activity in different samples sequentially.

Results are presented as a graphic, and corrected for the decay of the sample.