Bq

Unit system
Unit of	Radioactivity
Symbol	Bq
Named after

The Becquerel (symbol: Bq) is the SI derived unit of radioactivity. It is named after Henri Becquerel, who discovered radioactivity in 1896. One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second.

History

The unit was named in honor of Henri Becquerel, a French physicist who, along with Marie Curie and Pierre Curie, was awarded the Nobel Prize in Physics in 1903 for their joint research on radiation phenomena. The becquerel was adopted as the SI unit of radioactivity in 1975, replacing the curie (Ci), which was the previous unit of radioactivity.

Definition

The becquerel is defined as one disintegration per second. It is a measure of the rate at which a sample of radioactive material is decaying. The becquerel is a very small unit, and in practice, radioactivity is often measured in larger units such as the kilobecquerel (kBq), megabecquerel (MBq), or gigabecquerel (GBq).

Relation to Other Units

The becquerel is related to the curie, an older unit of radioactivity. One curie is equal to 3.7 × 10^10 becquerels. This means that one curie is the activity of a quantity of radioactive material in which 3.7 × 10^10 nuclei decay per second.

Applications

The becquerel is used in various fields such as nuclear medicine, radiation therapy, radiobiology, and environmental science. In nuclear medicine, the activity of a radioactive tracer is often measured in becquerels to determine the appropriate dosage for diagnostic or therapeutic purposes.

Measurement

Radioactivity is measured using instruments such as Geiger-Müller counters, scintillation counters, and ionization chambers. These devices detect the ionizing radiation emitted by radioactive substances and provide a measure of the activity in becquerels.

Health and Safety

Exposure to radioactive materials is measured in terms of absorbed dose, which is expressed in grays (Gy) or sieverts (Sv). The becquerel itself does not provide information about the potential biological effects of radiation, as it only measures the rate of decay. The biological impact depends on the type of radiation, the energy of the particles, and the duration of exposure.

Regulation

The use and disposal of radioactive materials are regulated by national and international agencies to ensure safety and minimize exposure to ionizing radiation. Guidelines are provided by organizations such as the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO).

See Also

• Curie (unit)
• Radioactivity
• Henri Becquerel
• Nuclear medicine
• Radiation protection