becquerel – a unit of radioactivity defined as the number of unstable nuclei which decay per second in a source

(pronounced bek-uh-rel)

Note: Becquerels symbol is "Bq".

To remember the meaning of becquerel, use the following mnemonic:

She beckoned her relatives (becquerel) out from under the stable, one every second (unstable decay every second).

Although a Geiger-muller counter can count the number of radioactive particles passing through its tube in an area around a sample, this is not accurate enough for the total number of unstable atomic nucleus that are decaying per second for the whole sample. For an accurate total decay per second this would have to be carried out in a laboratory and compared to a known sample in the same test conditions. A very accurate machine must be used to also pick up lower gamma ray emissions. Corrections must be applied to subtract counts from natural background radiation.

To find the true becquerel rate a physician must use calibrated detections, certified standards, controlled parameters, and apply precise physical corrections.