Thermoluminescence of CVD diamond films used in photon dosimetry

The diamond films, properties of which art: presented in this contribution, were grown on a silicon substrate using the microwave plasma-enhanced chem ical vapour deposition (MPECVD) technique, The films were characterised by means of Raman/photoluminescence/FTIR spectroscopy, XRD, RES and elastic re coil detection analysis (ERDA). Thermoluminescent (TL) responses of this ma terial to photons provided by radionuclide Co-60 source (1.173/1.332MeV) ov er a dose range from 1 to 50 Gy were measured. During the initial, i.e. fir st irradiation cycle, the dependencies of TL signals on the gamma -ray dose s seem to be quite linear up to 20 Gy. However, dramatic changes in the evo lution of the TL signals occur during further irradiation, i. e. when the i rradiation continues with another irradiation cycle. Then the sensitivity o f the TL material to high-energy photons increases significantly with the d ose. An explanation of this phenomenon lies very likely in the radiation dr iven formation of TL active defects.