Mixed high energy photon and electron radiation fields for calibrating radiation protection dosemeters

According to ISO 4037-3, calibrations of radiation protection dosemeters with photon radiation of energies above 3 MeV are performed under conditions of charged particle equilibrium. No information is provided concerning how to determine the response of dosemeters to radiation fields in the more general case when these conditions are not fulfilled. This paper deals with the production of mixed high energy photon and electron fields characterised by a lack or an excess of charged particles relative to conditions of equilibrium and describes a new procedure for the dosimetry in such fields. Through variation of the charged particle fluence fraction with respect to a nearly constant photon fluence, Hp(10) and H'(10) values varied by up to a factor of 1.74. The above mentioned basic study was utilised in the recent IAEA intercomparison (Co-ordinated Research Project 1996-1998) and EURADOS 'trial performance test' (1996-1998) for individual monitoring of photon radiation in testing response characteristics of individual dosemeters in non-charged particle equilibrium conditions.