Evluation of diamond radiation dosemeters.

The effect of beam energy, dose rate and temperature on seven commercial diamond electrical conductivity detectors was studied. The diamond dimensions were approximately 1 mm X 1 mm X 3 mm. Clinical photon nd electron beams were used for irradiation. The photon energy response normalised to 60Co was observed to have a maximum of 1.37 +/- 0.06 at 122 keV and the dose rate response was slightly non-linear, in agreement with the theory for insulators. Temperature effects were small and different for each detector. Two of the seven detectors gave repeatable results (+/- 5%) over five years, two others were much less satisfactory and three were rejected after preliminary tests. It is concluded that natural diamond can be used for the manufacture of reliable, small and near soft-tissue-equivalent dosemeters but that until the crystal selection and final product testing have been adequately standardised, the user needs to select the reliable dosemeters from a batch.