CVD diamond gamma dose rate monitor for harsh environment

The ability to operate in corrosive media, at high temperatures and the tolerance to high doses all make diamond particularly attractive for radiation detection in hostile environments. The emergence of low cost, reproducible, and high-quality diamond films grown by microwave plasma enhanced chemical vapour deposition (CVD) techniques has enabled the development of diamond devices as radiation detectors for applications in the nuclear industry or high-energy physics experiments. Dose rate measurements performed on CVD diamond detectors manufactured at CEA/LETI demonstrated the high interest of this material for X- and gamma-ray dose rates in harsh environments. Detectors with active surfaces ranging from 0.5 to 20 cm2 have been tested at dose rates from 1 mGy/h to 1 kGy/h. Good linearity and response stability has been observed over six decades. Due to the large band gap of diamond (5.5 eV), the detectors exhibit very low leakage current (<1 pA/cm2 at room temperature) and can be operated at high temperatures. No significant degradation of the detector performances have been observed after three weeks of operation corresponding to an integrated dose value greater than 500 kGy, while irradiation with a 3×105 n cm−2 neutron fluence resulted in a slight degradation of the charge collection efficiency of approximately 25%.