Plasma and Fusion Research

Volume 17, 2405045 (2022)

Regular Articles

Thermal Neutron Measurement Capability of a Single Crystal CVD Diamond Detector near the Reactor Core Region of UTR-KINKI
Makoto I. KOBAYASHI1,2), Sachiko YOSHIHASHI3), Hirokuni YAMANISHI4), Siriyaporn SANGAROON1,5), Kunihiro OGAWA1,2), Mitsutaka ISOBE1,2), Akira URITANI3) and Masaki OSAKABE1,2)
1)
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu 509-5292, Japan
2)
The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu 509-5292, Japan
3)
Nagoya University, Nagoya, Aichi 464-8603, Japan
4)
Kindai University, Atomic Energy Research Institute, Osaka 577-8502, Japan
5)
Mahasarakham University, Thailand
(Received 16 December 2021 / Accepted 21 February 2022 / Published 6 June 2022)

Abstract

Thermal neutron flux evaluation using a single crystal diamond detector (SDD) was carried out in the core region of the UTR-KINKI reactor where a mixed radiation field by thermal and fast neutrons and gamma-ray exists. The pulse shape discrimination method to extract pulses with a rectangular shape as well as a wide pulse-width was established to exclude pulses induced by gamma-rays. The SDD, using a 6LiF thermal neutron converter, is able to detect pulse events caused not only by fast neutrons but also by thermal neutrons through energy depositions into the diamond by energetic alpha and triton particles induced by thermal neutrons. Additionally, the SDD without the thermal neutron converter was used for the measurement of the energy deposition events only by fast neutrons. A comparison of the pulse counts of the SDD with or without the thermal neutron convertor deduced the energy deposition spectra by thermal neutrons. The thermal neutron flux in the core region of the UTR-KINKI reactor was evaluated to be 7.6 × 106 n cm−2 s−1 W−1 up to a reactor power of 1 W.

Keywords

neutron, diamond detector, UTR-KINKI, TBR

DOI: 10.1585/pfr.17.2405045

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