Thermoluminescence in CVD diamond films: application to radiation dosimetry

In this work, we report the analysis of TL features of CVD diamond samples after exposure to (90)Sr/(90)Yr beta particles. The glow curves have been analysed in order to determine the trapping kinetics and the activation energies of the trapping levels. They have been interpreted as due to a first-order trap emptying process with activation energies ranging from 0.98 to 1.12 eV. Owing to the great practical interest of diamond in radiotherapy, we: have explored the application of CVD diamond as TL dosimeter. The dose-response of the CVD diamond film to beta irradiation was investigated at clinical application doses and compared with the response of LiF TL100 samples. Moreover, measurements of charge pulses induced by 5.4 MeV alpha particles were carried out in order to investigate the effect of beta particle pre-irradiation (or 'priming') on the charge collection efficiency. The saturation of hole trapping levels evaluated by glow curve analysis was shown to be strictly related to the improvement of charge collection efficiency. A model of the charge carrier dynamics is also presented which accounts for the optical bleaching of glow curve and alpha particle spectra. (C) 1999 Elsevier Science S.A. All rights reserved.