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

Abstract

The fast neutron response of a single-crystal diamond (SCD) detector was studied up to 300 °C. The SCD detector was fabricated using a $5\,\,\text {mm}\times 5\,\,\text {mm}\times 0.4\,\,\text {mm}$ 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/ $\mu \text{m}$ . 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, $\alpha)^{9}$ Be 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.