Radiometric temperature comparisons of three NIST gold freezing-point blackbodies

Abstract

Radiometric temperature comparisons of three NIST gold freezing-temperature blackbodies are described. The blackbodies are used in different facilities with different furnaces for the radiance temperature and spectral radiance scales, and the comparisons are needed to determine the equivalence of the gold-point based realizations. The temperatures of each gold-point blackbody are compared against each other using a detector-based radiation thermometer which is calibrated using the cryogenic electrical substitution radiometer. These measurements were performed over a month period in 2004 and compared to the previous measurements of two of the same blackbodies in 1991. The freezing temperatures of all three blackbodies are found to be in agreement to <10 mK (k = 2), and the differences are within the comparison uncertainties. These differences are in agreement, within the combined uncertainties, with the <16 mK (k = 1) differences found in 1991. © 2011 Springer Science+Business Media, LLC (Outside the USA).