Pertains to transportable, mobile or installed assemblies intended to measure environmental air kerma rates or air absorbed dose rates from 30 nGy.h[-1] to 30 [mu]Gy.h[-1] or ambient dose equivalent rates from 30 nSv.h[-1] to 30 [mu]Sv.h[-1], or air kerma or air absorbed dose from 10 nGy to 10 mGy, or ambient dose equivalent from 10 nSv to 10 mSv, due to photon radiation of energy between 50 keV and 7 MeV.