Becquereln.
1. Used attributively in Becquerel('s) rays, formerly a general term for the radiation from radioactive substances.
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1896 S. P. Thompson in London, Edinb. & Dublin Philos. Mag. 5th Ser. July 105 While agreeing with the Röntgen rays in the property of penetrating aluminium [etc.], the Becquerel rays differ in the circumstance that they can be refracted and polarized.
1897 S. P. Thompson Light Visible & Invis. 279 Becquerel's rays possess..the property of diselectrifying charged bodies.
1898 Physical Rev. Apr. 239 Becquerel rays, or uranium rays, as Becquerel himself called them.
1931 Discovery July 212/2 When X-rays and the Becquerel rays from uranium were discovered it was demonstrated that these rays could make air into a conductor.
2. (Written becquerel.) The SI unit of radioactivity, equal to one disintegration per second (superseding the curie, equal to 3·7 × 1010 becquerels). Symbol Bq.
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the world > matter > physics > atomic nucleus > measurement of ionizing radiation > [noun] > units of radioactivity
megacurie1947
curie1954
pico-curie1960
Becquerel1975
Bq1975
1975 Physics Bull. Mar. 105/1 The CIPM will recommend to the CGPM that the SI unit of activity should be given the name ‘becquerel’, symbol Bq.
1976 Sci. Amer. Mar. 60 a/2 Among the SI's derived units with special names are those for..radioactivity (the becquerel, or spontaneous nuclear transitions per second) and absorbed dose of radiation (the gray, or joules per kilogram).
1986 Times 7 May 7 The Agriculture Minister insisted that his official figures for iodine radiation in milk showed levels up to 60 becquerels a litre, ‘miles below’ the safe limit of 1,000.
This entry has not yet been fully updated (first published 1933; most recently modified version published online December 2018).
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