Measurement of 6Li burn-up reaction rate using a single crystal CVD diamond detector under fast neutron irradiation environment

• Published in: Fusion engineering and design Vol. 193; p. 113799
• Main Authors: Kobayashi, Makoto I., Yoshihashi, Sachiko, Ogawa, Kunihiro, Isobe, Mitsutaka, Miwa, Misako, Toyama, Sho, Matsuyama, Shigeo, Osakabe, Masaki
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2023
• Subjects: Blanket; Diamond detector; Neutron; Tritium; Tritium; Blanket; Neutron; Diamond detector
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2023.113799

•The measurement technique for nuclear reaction products in 6Li burn-up reaction was developed using the single crystal CVD diamond (SCD) detectors with LiF foil under the fast neutron irradiation.•The pulse shape discrimination process separated the events by fast neutron collision at the incident surface, the ballistic center region, and the rear surface of the SCD, and rejected the events caused by gamma-rays.•The additional analyses using deduced count rates at the incident surface and the ballistic center region of the SCD demonstrated the quantitative measurement for nuclear reaction products produced by 6Li burn-up reaction under fast neutron irradiation condition. The study aimed to develop a technique for measuring the 6Li burn-up rate using a single crystal diamond (SCD) detector (SDD) made by chemical vapor deposition (CVD) with a thin lithium fluoride foil. The method relied on pulse shape discrimination (PSD) to separate pulses by nuclear reaction products of 6Li from pulses due to fast neutrons and gamma-rays. By applying the PSD method, the rectangular shape pulses induced by events occurred at the specific depth positions of the SCD, i.e., the incident surface, the ballistic center region (BCR), and the rear surface, were extracted. Thereafter, pulses occurred each specific depth position of the SCD were discriminated according to the pulse width. Due to a short range of nuclear reaction products in the SCD, pulses at the incident surface should be induced by both fast neutrons and nuclear reaction products, although pulses at the BCR are caused by fast neutron only. The study demonstrated that quantitative measurements of nuclear reaction products in the 6Li burn-up reaction under fast neutron irradiation can be achieved using only one SDD by analyzing event rates at the incident surface and in the BCR region.