Neutron-induced signal on the single crystal chemical vapor deposition diamond-based neutral particle analyzer

S. Kamio, Y. Fujiwara, K. Ogawa, M. I. Kobayashi, S. Sangaroon, M. Isobe, R. Seki, H. Nuga, M. Osakabe, S. Matsuyama, M. Miwa, S. Toyama

Research output: Contribution to journalArticlepeer-review

Abstract

A diamond-based neutral particle analyzer (DNPA) array composed of single-crystal chemical vapor deposition (sCVD) diamond detectors was installed on the Large Helical Device (LHD) for measuring the helically trapped energetic particles. In high neutron flux experiments, the unwanted neutron-induced pulse counting rate should be estimated using the neutron diagnostics because a diamond detector is sensitive to neutrons as well as energetic neutral particles. In order to evaluate the quantitative neutron-induced pulse counting rate on the DNPA, the response functions of the sCVD diamond detector for mono-energetic neutrons were obtained using accelerator-based D-D and D-7Li neutron sources in Fast Neutron Laboratory (FNL). As a result of the neutron flux estimation by the Monte Carlo N-Particle code at the NPA position in the LHD and the response function obtained in the FNL experiment, the counting rate of the neutron-induced signal was predicted to be 1.1 kcps for the source neutron emission rate of Sn = 1 × 1015 n/s. In the LHD experiment, the neutron-induced signals were observed by closing the gate valve during the plasma discharges. It is found that the counting rates of the neutron-induced signals proportional to Sn reached 1.1 kcps at Sn = 1 × 1015 n/s. As a result of the quantitative estimation of the neutron-induced signals on the DNPA using other neutron measurements, it has become possible to accurately measure energetic neutral particles in the high neutron flux experiment.

Original languageEnglish
Article number113304
JournalReview of Scientific Instruments
Volume91
Issue number11
DOIs
Publication statusPublished - 2020 Nov 1

ASJC Scopus subject areas

  • Instrumentation

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