Nuclear radiation detectors on various type diamonds

The sensitivity of radiation sensors based on various quality CVD diamond films was studied. The sensors were exposed to a low dose /spl gamma/ irradiation (/sup 60/Co source). The diamond substrates were characterised by optical absorption, photo (PL)- and cathodoluminescence (CL) techniques. The comparison of the radiation response signal to the results of the optical studies revealed that the Si related defects inside the single crystallites of the films strongly reduce the sensitivity of the sensors and cause large ionisation currents. It was shown that the free exciton recombination intensity in CL can serve as a direct measure of the radiation sensitivity of diamond. Also it was demonstrated that optical absorption can only be used for initial selection of the diamond substrates.