A Study of the Fast Neutron Response of a Single-Crystal Diamond Detector at High Temperatures

The fast neutron response of a single-crystal diamond (SCD) detector was studied up to 300 °C. The SCD detector was fabricated using a 5 mm×5 mm×0.4 mm substrate with premetallization treatments for obtaining oxygen terminated surfaces. The electrical contacts to the detector were provided by Cr/Au metallization. The performance of the fabricated detector was investigated using leakage current versus bias voltage (I-V) measurements and using pulse height spectra measurements with 5.5 MeV alphas and 14 MeV fast neutrons. The leakage current was observed to be about 400-600 pA at a field of 1 V/μm. From the full-width half-maximum of the alpha peak at 5.5 MeV, an energy resolution of about 2.1 ± 0.1% was estimated. The fast neutron response measurements were carried out using a 14 MeV deuterium-tritium neutron source. No measurable degradation of the detector performance was observed up to the maximum studied temperature of 300 °C. The neutron spectrum obtained at 300 °C showed a well-defined peak at 8.5 MeV due to the ¹²C(n, α)⁹Be reaction which was the same as that observed at room temperature. Considering the total integrated counts, the detector sensitivity was observed to be 10^-2 count per neutron. The results presented in this paper demonstrate for the first time the high temperature operation of an SCD detector up to 300 °C. These results also suggest that such SCD detectors could be used at higher temperatures for neutron diagnostics in the future fusion plasma facilities such as International Thermonuclear Experimental Reactor.