The NPL Air Kerma Primary Standard PS5-1/PS5-2 for 137CS and 60CO: Summary Of Factors Including ICRU 90 Recommendations

The NPL air kerma primary standard ionisation chambers PS5-1 and PS5-2 for 137Cs and 60Co were established in 2017. Certain factors pertinent to these standards have required re-evaluation following the recommendations contained in the International Commission for Radiation Measurements and Units Report 90. This report summarises the re-evaluated factors and those unaffected by the adoption of the recommendations.