4.1 This practice is applicable to the use of a calorimeter for the measurement of absorbed dose in electron beams, the qualification of electron irradiation facilities, periodic checks of operating parameters of electron irradiation facilities, and calibration of other dosimeters in electron beams.

NOTE 1 - For additional information of the use of dosimetry in electron accelerator facilities, see ISO/ASTM Practices 51431 and 51649, and ICRU Reports 34 and 35, and Refs (1-3).4

4.2 The calorimeters described in this practice are not primary-standard dosimeters. They may be used as transferstandard dosimeters or as internal standards at an electron beam irradiation facility, or may be routine dosimeters used for routine dose measurements. The calorimeters are calibrated by comparison with transfer-standard dosimeters.

4.3 The dose measurement is based on the measurement of the temperature rise in an absorber (calorimetric body) irradiated by an electron beam. Different absorbing materials are used, but the response is usually defined in terms of dose to water.

4.4 The absorbed dose in other materials irradiated under equivalent conditions may be calculated. Procedures for making such calculations are given in ASTM Practices E 666 and E 668, ISO/ASTM Guide 51261, and Ref (1).

4.5 The average absorbed dose in the volume of the calorimetric body is measured. Dose gradients may occur in this volume and may have to be considered when estimating dose in other materials.

4.6 The calorimetric bodies of the calorimeters described in this practice are made from low atomic number materials. The electron fluences within these calorimetric bodies will be approximately equal when irradiated with electron beams of 1.5 MeV or higher. Calibration in terms of dose to water is possible for these calorimeters.

4.6.1 Calorimeters for use at industrial electron accelerators have been constructed using graphite, polystyrene or a Petri dish filled with water as the calorimetric body (4-10). The thickness of the calorimetric body shall be less than the range of the electrons for the specified material.

4.6.2 Polymeric materials other than polystyrene may be used for calorimetric measurements. Polystyrene is used because it is known to be resistant to radiation (11) and because no exo- or endothermic reactions take place (12).