Becquerel

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"Bq" and "MBq" redirect here. For other uses, see BQ, MBQ, and Becquerel (disambiguation).
becquerel
SI
Unit ofactivity
SymbolBq
Named afterHenri Becquerel
Conversions
1 Bq in ...... is equal to ...
   rutherford   10−6 Rd
   curie   2.703×10−11 Ci ≅ 27 pCi
   SI base unit   s−1

The becquerel (

SI multiples of the unit are commonly used.[2]

The becquerel is named after Henri Becquerel, who shared a Nobel Prize in Physics with Pierre and Marie Curie in 1903 for their work in discovering radioactivity.[3]

Definition

1 Bq = 1 s−1

A special name was introduced for the

aperiodic
radioactive decays.

The

rads. Decay activity was measured in curies before 1946 and often in rutherfords between 1946[7]
and 1975.

Unit capitalization and prefixes

As with every International System of Units (SI) unit named after a person, the first letter of its symbol is uppercase (Bq). However, when an SI unit is spelled out in English, it should always begin with a lowercase letter (becquerel)—except in a situation where any word in that position would be capitalized, such as at the beginning of a sentence or in material using title case.[8]

Like any SI unit, Bq can be

prefixed
; commonly used multiples are kBq (kilobecquerel, 103 Bq), MBq (megabecquerel, 106 Bq, equivalent to 1 rutherford), GBq (gigabecquerel, 109 Bq), TBq (terabecquerel, 1012 Bq), and PBq (petabecquerel, 1015 Bq). Large prefixes are common for practical uses of the unit.

Examples

For practical applications, 1 Bq is a small unit. For example, there is roughly 0.017 g of potassium-40 in a typical human body, producing about 4,400 decays per second (Bq).[9]

The activity of radioactive americium in a home smoke detector is about 37 kBq (1 μCi).[10]

The global inventory of

exabecquerel).[11]

These examples are useful for comparing the amount of activity of these radioactive materials, but should not be confused with the amount of exposure to ionizing radiation that these materials represent. The level of exposure and thus the absorbed dose received are what should be considered when assessing the effects of ionizing radiation on humans.

Relation to the curie

The becquerel succeeded the curie (Ci),[12] an older, non-SI unit of radioactivity based on the activity of 1 gram of radium-226. The curie is defined as 3.7×1010 s−1, or 37 GBq.[4][13]

Conversion factors:

  • 1 Ci = 3.7×1010 Bq = 37 GBq
  • 1 μCi = 37,000 Bq = 37 kBq
  • 1 Bq = 2.7×10−11 Ci = 2.7×10−5 μCi
  • 1 MBq = 0.027 mCi

Relation to other radiation-related quantities

Graphic showing relationships between radioactivity and detected ionizing radiation

The following table shows radiation quantities in SI and non-SI units. WR (formerly 'Q' factor) is a factor that scales the biological effect for different types of radiation, relative to x-rays (e.g. 1 for beta radiation, 20 for alpha radiation, and a complicated function of energy for neutrons). In general, conversion between rates of emission, the density of radiation, the fraction absorbed, and the biological effects, requires knowledge of the geometry between source and target, the energy and the type of the radiation emitted, among other factors.[14][not specific enough to verify]

Ionizing radiation related quantities
Quantity Unit Symbol Derivation Year SI equivalent
Activity (A) becquerel Bq s−1 1974 SI unit
curie Ci 3.7 × 1010 s−1 1953 3.7×1010 Bq
rutherford Rd 106 s−1 1946 1,000,000 Bq
Exposure (X) coulomb per kilogram C/kg C⋅kg−1 of air 1974 SI unit
röntgen R esu / 0.001293 g of air 1928 2.58 × 10−4 C/kg
Absorbed dose (D) gray Gy J⋅kg−1 1974 SI unit
erg per gram erg/g erg⋅g−1 1950 1.0 × 10−4 Gy
rad
 rad 100 erg⋅g−1 1953 0.010 Gy
Equivalent dose (H) sievert Sv J⋅kg−1 × WR 1977 SI unit
röntgen equivalent man rem 100 erg⋅g−1 × WR 1971 0.010 Sv
Effective dose (E) sievert Sv J⋅kg−1 × WR × WT 1977 SI unit
röntgen equivalent man rem 100 erg⋅g−1 × WR × WT 1971 0.010 Sv

See also

References

  1. ^ "Radioactivity: Radioactive Activity Doses". radioactivity.eu.com. Archived from the original on 2020-02-20. Retrieved 2020-02-20.
  2. ^ "Radiation Protection Guidance For Hospital Staff – Stanford Environmental Health & Safety". ehs.stanford.edu. Retrieved 2020-02-20.
  3. BIPM
    . Retrieved 2012-10-24.
  4. ^
    S2CID 250749337
  5. BIPM
    . Retrieved 2015-07-19. (d) The hertz is used only for periodic phenomena, and the becquerel is used only for stochastic processes in activity referred to a radionuclide.
  6. PMID 1251122
    .
  7. S2CID 5343688
    .
  8. ^ "SI Brochure: The International System of Units (SI)". SI Brochure (8 ed.).
    BIPM
    . 2014.
  9. ^ "Radioactive Human Body". Harvard Natural Sciences Lecture Demonstrations.
  10. ^ "Smoke Detector (1970s)". Museum of Radiation and Radioactivity. Retrieved 25 September 2023.
  11. ISBN 978-0-7506-7463-8
    .
  12. ^ It was adopted by the BIPM in 1975, see resolution 8 of the 15th CGPM meeting
  13. ^ Resolution 7 of the 12th CGPM Archived 2021-02-19 at the Wayback Machine (1964)
  14. ^ Baes, Fred. "hps.org". Health Physics Society. Retrieved 2022-10-03.

External links

Look up becquerel in Wiktionary, the free dictionary.
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