Since the gray and the sievert are associated with relative biological effectiveness of the radiation and the katal is associated with catalytic activity, do the gray (Gy), sievert (Sv) and katal (kat) have a use in pure physics? Did the International System of Units (SI) standardize some units entirely for biology, chemistry and/or biophysics?
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2$\begingroup$ Units for radiation measurements are a huge mess, particularly because of the difference between ‘energy absorbed’ and ‘health impact to humans’ - but as a human physicist you could well worry about both. $\endgroup$– Jon CusterCommented Apr 24, 2020 at 12:01
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2$\begingroup$ The gray is simply energy absorbed per unit mass (J/kg) and has nothing to say about the biological effectiveness of radiation. When you start taking into account radiation type and tissue type weighting factors, that's when Gy becomes Sv. $\endgroup$– imabugCommented Apr 26, 2020 at 12:40
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$\begingroup$ @imabug so grays are to sieverts what watts are to lumens? $\endgroup$– No NameCommented Jul 16, 2023 at 19:15
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To answer your second question: yes, kinda. The candela is a biological weighting of radiant intensity. It is also an SI base unit. It, and its derivations lumen and lux, are only used in photometry, the study of lighting and its effects on perception both biological (eyes) and mechanical (cameras).
