ERS dose calibrator reference sources are calibrated by direct comparison of standardized solutions traceable to the National Institute of Standards and Technology (NIST), in an identical geometry, using a pressurized ion chamber with ±%5 accuracy. Dose Calibrator sources are manufactured by adding 20 ml activity of epoxy composition in 30 ml volumed of polyethelen vial. Each dose calibrator source has its own colored-coded epoxy. Cobalt-57,
Cobalt-60, Cesium-137, Barium-133 dose calibrator reference sources can be supplied in set or individually in accordance with customer request.