Comparison of the ambient dose equivalent rate for photon radiation

Project Description

The Cs-137 and N-60 beams are typically used for calibration of radiation protection instrumentation in terms of the operational dose equivalent quantity H*(10).
This comparison is required to support the 17 EURAMET member laboratories' relevant published CMC lines, to investigate the different realisations of the wide dose rate range of collimated Cs-137 beams, to investigate the field homogeneity and the stated uncertainties.
This comparison is focused on the special needs for calibration of area dosemeters: large radiation fields and low dose rates (10 µSv/h and 1 mSv/h) at the mostly used radiation qualities S-Cs and N-60 (only at 1 mSv/h) of the ISO 4037 narrow spectrum series.
The proposed transfer instrument is a spherical ionisation chambers having 10 litre volume. The large diameter of this chamber is chosen to take into account the challenge of calibration in large homogeneous fields.
Each participant should calibrate the transfer chamber at the radiation qualities S-Cs and N-60 of the ISO 4037 narrow spectrum series in terms of H*(10).
The comparison reference value Ci(NH) will be determined at each radiation quality and dose rate as the arithmetic mean of the calibration factor NH given by the participants. Only values from participants with traceability for Ka to their own primary standard will contribute to the comparison reference value.

Final Report 2018-08-27

The comparison has been completed and results are published in the KCDB.