= L. L. Lucas
{c}
L. L. Lucas authored a 2000 comparison of <water> standards containing <tritium>, using <liquid scintillation counting> to measure their <massic activity> ratios. <Massic activity> is <radioactive activity> divided by sample mass. The work compared these measured ratios with ratios obtained from recorded mass-based dilutions, finding agreement within the stated <measurement uncertainties>.<Massic Activity Ratios of the NBS NIST Tritiated-Water Standards Issued Between 1954 and 1999 by L. L. Lucas>[Abstract, Journal of Research of NIST 105 (2000), pp. 535–539; DOI 10.6028/jres.105.042.]{ref}
The comparison illustrates an important <measurement calibration> principle: independently obtained ratios can test consistency without making every source of error disappear. Agreement between counting and dilution supports the relationship between the standards. It does not imply zero <measurement uncertainty>, nor does it by itself establish an absolute <radioactive activity> scale. The study's contribution was a quantitative connection between reference samples, rather than simply a count from one detector.<Massic Activity Ratios of the NBS NIST Tritiated-Water Standards Issued Between 1954 and 1999 by L. L. Lucas>[Abstract: measured ratios versus gravimetric-dilution ratios.]{ref}
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