[Table of Contents]

Plasma and Fusion Research

Volume 8, 1402144 (2013)

Regular Articles

Research and Development of Neutron Detection System using Scintillator and Digital-Signal Processing
Kouji SHINOHARA, Keiichi ISHII1), Kentaro OCHIAI, Mamoru BABA2), Mamiko SASAO3) and Sumio KITAJIMA1)
Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
1)
Department of Quantum Science and Energy Engineering, Tohoku University, Sendai, Miyagi 980-8579, Japan
2)
Cyclotron and Radioisotope Center, Tohoku University, Sendai, Miyagi 980-8578, Japan
3)
Organization for Research Initiatives and Development, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan
(Received 8 July 2013 / Accepted 26 August 2013 / Published 15 November 2013)

Abstract

A collimated neutron flux array system in JT-60U successfully upgraded performance of higher counting rate and the capability to detect 14 MeV neutrons as well by using a fast digitizer in 2006. Additionally, detailed analysis of the recorded waveform on JT-60U and FNS has provided us new findings. In this paper, firstly, characteristics of pulse shapes and neutron-gamma discrimination parameters investigated by the detailed analysis of digitized waveform data are described. Next, new data analysis procedure for neutron-gamma discrimination based on the characteristics is proposed. In the new procedure, an appropriate projection surface, on which we can define the discrimination boundary, has been introduced in three-dimensional discrimination parameter space. The problem of “pulse height variation”, which occurs when a counting rate is high in high performance plasma, and its countermeasures are also presented. The system using the countermeasure of a booster method successfully has avoided the problem in the high neutron flux condition of ∼2 × 105 counts/s on FNS.

Keywords

neutron measurement, neutron-gamma discrimination, scintillator, fast digitizer, JT-60U, FNS

DOI: 10.1585/pfr.8.1402144

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References

  • [1] A.L. Roquemore, R.C. Chouniard, M. Diesso et al., Rev. Sci. Instrum. 61, 3163 (1990).
  • [2] J.M. Adams, O.N. Jarvis, G.J. Sadler et al., Nucl. Instrum. Methods 329, 277 (1993).
  • [3] O.N. Jarvis, J.M. Adams, F.B. Marcus and G.J. Sadler, Fusion Eng. Des. 34-35, 59 (1997).
  • [4] M. Ishikawa, T. Nishitani, A. Morioka et al., Rev. Sci. Instrum. 73, 4237 (2002).
  • [5] W.W. Heidbrink et al., Plasma Phys. Control. Fusion 46, 1855 (2004).
  • [6] S.J. Zweben et al., Nucl. Fusion 30, 1551 (1990).
  • [7] D.S. Darrow et al., Rev. Sci. Instrum. 66, 476 (1995).
  • [8] S.S. Medley and A.L. Roquemore, Rev. Sci. Instrum. 69, 2651 (1998).
  • [9] A. Klasilnikov et al., J. Plasma Fusion Res. 75, 967 (1999).
  • [10] M. Osakabe et al., Rev. Sci. Instrum. 72, 788 (2001).
  • [11] K. Shinohara, M. Takechi, M. Ishikawa et al., Nucl. Fusion 42, 942 (2002).
  • [12] M. Ishikawa, M. Takechi, K. Shinohara et al., Nucl. Fusion 45, 1474 (2005).
  • [13] M. Ishikawa, M. Takechi, K. Shinohara et al., Nucl. Fusion 46, S898 (2006).
  • [14] T. Suzuki et al., Nucl. Fusion 48, 045002 (2007).
  • [15] M. Ishikawa, T. Itoga, T. Okuji et al., Rev. Sci. Instrum. 77, 10E706 (2006).
  • [16] T. Itoga, M. Ishikawa, M. Baba et al., Radiat. Prot. Dosimetry 126, 380 (2007).
  • [17] K. Shinohara, T. Okuji, M. Ishikawa, M. Baba and T. Itoga, Rev. Sci. Instrum. 79, 10E509 (2008).
  • [18] F.D. Brooks, Nucl. Instrum. Methods 162, 477 (1979).
  • [19] K. Ishii, K. Shinohara, M. Ishikawa, T. Okuji, M. Baba, M. Isobe, S. Kitajima and M. Sasao, Plasma Fusion Res. 5, S1043 (2010).
  • [20] K. Ishii, K. Shinohara, M. Ishikawa, M. Baba, M. Isobe, A. Okamoto, S. Kitajima and M. Sasao, Rev. Sci. Instrum. 81, 10D334 (2010).
  • [21] Photomultiplier tubes -Basics and Application (Third Edition), Editted by T. Hakamata et al., Hamamatsu Photonics K.K., (2005).
  • [22] M. Osakabe et al., “Improvement of the neutron energy spectrometer, COTETRA (Counter Telescope with Thick Radiator)” in Proceedings of the international school of plasma physics “Piero Caldirola” workshop on Diagnostics for Experimental Fusion Reactor, September 4-12, 1997, Varena, Italy, ISBN 0-306-45835-7, printed in “Diagnostics for Experimental Thermonuclear Fusion Reactors 2 (No. 2)”, Editted by P.E. Stott et al., (Plenum Press, 1998), p.451.

This paper may be cited as follows:

Kouji SHINOHARA, Keiichi ISHII, Kentaro OCHIAI, Mamoru BABA, Mamiko SASAO and Sumio KITAJIMA, Plasma Fusion Res. 8, 1402144 (2013).