Response function measurement for 14 MeV neutrons by a CVD single diamond crystal synthesized with high-growth rate
Sato, Kei*; Kakimoto, Akinori*; Kaneko, Junichi* ; Fujita, Fumiyuki*; Tsubouchi, Nobuteru*; Mokuno, Yoshiaki*; Chayahara, Akiyoshi*; Sato, Satoshi; Konno, Yuta*; Homma, Akira*; Shikata, Shinichi*; Furusaka, Michihiro*
As a part of development of diamond energy spectrometers using the C(n,)Be reaction for DT plasma ion temperature measurement, response functions measurement of chemical vapor deposition (CVD) single crystal diamonds for alpha particles and 14 MeV neutrons were carried out. One diamond sample was synthesized by the national institute of advanced industrial science and technology (AIST) aiming at a large size and high-quality substrate for electric device with higher methane concentration of 10%. This diamond crystal was chosen according to intensity of free exciton recombination luminescence. In addition, a CVD single crystal diamond, categorized in "detector grade" synthesized by Element 6 Inc. was evaluated.Response function measurement of 14 MeV neutrons were carried out at the Fusion Neutronic Source facility of Japan Atomic Energy Agency. Energy resolutions of 4.3% and 5.2% for the C(n,)Be reaction were obtained by the two CVD diamond single crystals. In general, energy spectrometer grade CVD diamond single crystals are grown using lower methane concentration, i.e., 1%. However, this results revealed that even higher methane concentration of 10% can grow energy spectrometer grade CVD diamond single crystals.