Characteristics of silicon and diamond detectors in a 60 MeV proton beam.

The calibration factor variation for a PTW natural diamond detector and a Scanditronix p-type stereotactic silicon diode (designed for use in photon beams) was studied in the 10-59 MeV range. Irradiations were performed in a water phantom with the 60 MeV ocular therapy beam at the CCO (UK). The diamond detector showed a sensitivity increase with energy, underestimating the dose by about 18% at the Bragg peak, by 7% at the centre and by 17% at the distal end of the SOBP region. The silicon diode did not show any significant sensitivity change with energy. However, a decrease in response of 24% was observed for an accumulated dose of 300 Gy.