calibrator

in activation analysis
synonym: comparator (obsolete)
https://doi.org/10.1351/goldbook.08717
Measured amount of an element with stated measurement uncertainty that is simultaneously irradiated with the sample during activation analysis.
Notes:
  1. The term 'calibrator' is preferred over 'comparator'.
  2. If one calibrator is used (single calibrator method, which is preferred over 'single comparator method'), it is essentially identical to a flux monitor (except that the latter is not necessarily linked to activation analysis).
Source:
PAC, 2021, 93, 69. 'Vocabulary of radioanalytical methods (IUPAC Recommendations 2020)' on page 73 (https://doi.org/10.1515/pac-2019-0302)