Measurement of Ambient Dose Equivalent and Directional Dose Equivalent in a 60Co Beam

An experimental determination is described of the ambient dose equivalent and directional dose equivalent at 1 g.cm-2 below the surface of the ICRU sphere, in the gamma radiation from 60Co. These quantities are related to exposure and kerma in air measured at the same point with an uncertainty not exceeding 0.3% for the ambient dose equivalent and 1% for the directional dose equivalent. A theoretical determination of these quantities has also been performed and gives values compatible with those obtained experimentally.