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Title: Development of Fast Measurement System of Neutron Emission Profile Using a Digital Signal Processing Technique in JT-60U

Abstract

Neutron emission profiles are routinely measured in JT-60U Tokamak. Stinbene neuron detectors (SNDs), which combine a Stilbene organic crystal scintillation detector (Stilbene detector) with an analog neutron-gamma pulse shape discrimination (PSD) circuit, have been used to measure neutron flux efficiently. Although the SND has many advantages as a neutron detector, the maximum count rate is limited up to {approx}1x 10{sup 5} counts/s due to the dead time of the analog PSD circuit. To overcome this issue, a digital signal processing (DSP) system using a Flash-ADC has been developed. In this system, anode signals from the photomultiplier of the Stilbene detector are fed to the Flash ADC and digitized. Then, the PSD between neutrons and gamma-rays are performed using software. The photomultiplier tube is also modified to suppress and correct gain fluctuation of the photomultiplier. The DSP system has been installed in the center channel of the vertical neutron collimator system in JT-60U and applied to measurements of neutron flux in JT-60U experiments. Neutron flux are successfully measured with count rate up to {approx}1x 10{sup 6} counts/s without the effect of pile up of detected pulses. The performance of the DSP system as a neutron detector is demonstrated.

Authors:
;  [1]; ; ; ; ;  [2]
  1. Japan Atomic Energy Agency, Mukoyama 801-1 Naka, Ibaraki 311-0193 (Japan)
  2. Cyclotron and Radioisotope Center, Tohoku University, Aoba, Sendai, Miyagi 980-8578 (Japan)
Publication Date:
OSTI Identifier:
21136785
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 988; Journal Issue: 1; Conference: International conference on burning plasma diagnostics, Varenna (Italy), 24-28 Sep 2007; Other Information: DOI: 10.1063/1.2905084; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ANALOG-TO-DIGITAL CONVERTERS; COUNTING RATES; DEAD TIME; FLUCTUATIONS; GAIN; JT-60U TOKAMAK; NEUTRON DETECTION; NEUTRON DETECTORS; NEUTRON EMISSION; NEUTRON FLUX; NEUTRONS; PERFORMANCE; PHOTOMULTIPLIERS; PLASMA DIAGNOSTICS; SCINTILLATION COUNTERS; STILBENE

Citation Formats

Ishikawa, M., Shinohara, K., Itoga, T., Okuji, T., Nakhostin, M., Baba, M., and Nishitani, T. Development of Fast Measurement System of Neutron Emission Profile Using a Digital Signal Processing Technique in JT-60U. United States: N. p., 2008. Web. doi:10.1063/1.2905084.
Ishikawa, M., Shinohara, K., Itoga, T., Okuji, T., Nakhostin, M., Baba, M., & Nishitani, T. Development of Fast Measurement System of Neutron Emission Profile Using a Digital Signal Processing Technique in JT-60U. United States. doi:10.1063/1.2905084.
Ishikawa, M., Shinohara, K., Itoga, T., Okuji, T., Nakhostin, M., Baba, M., and Nishitani, T. Wed . "Development of Fast Measurement System of Neutron Emission Profile Using a Digital Signal Processing Technique in JT-60U". United States. doi:10.1063/1.2905084.
@article{osti_21136785,
title = {Development of Fast Measurement System of Neutron Emission Profile Using a Digital Signal Processing Technique in JT-60U},
author = {Ishikawa, M. and Shinohara, K. and Itoga, T. and Okuji, T. and Nakhostin, M. and Baba, M. and Nishitani, T.},
abstractNote = {Neutron emission profiles are routinely measured in JT-60U Tokamak. Stinbene neuron detectors (SNDs), which combine a Stilbene organic crystal scintillation detector (Stilbene detector) with an analog neutron-gamma pulse shape discrimination (PSD) circuit, have been used to measure neutron flux efficiently. Although the SND has many advantages as a neutron detector, the maximum count rate is limited up to {approx}1x 10{sup 5} counts/s due to the dead time of the analog PSD circuit. To overcome this issue, a digital signal processing (DSP) system using a Flash-ADC has been developed. In this system, anode signals from the photomultiplier of the Stilbene detector are fed to the Flash ADC and digitized. Then, the PSD between neutrons and gamma-rays are performed using software. The photomultiplier tube is also modified to suppress and correct gain fluctuation of the photomultiplier. The DSP system has been installed in the center channel of the vertical neutron collimator system in JT-60U and applied to measurements of neutron flux in JT-60U experiments. Neutron flux are successfully measured with count rate up to {approx}1x 10{sup 6} counts/s without the effect of pile up of detected pulses. The performance of the DSP system as a neutron detector is demonstrated.},
doi = {10.1063/1.2905084},
journal = {AIP Conference Proceedings},
number = 1,
volume = 988,
place = {United States},
year = {Wed Mar 12 00:00:00 EDT 2008},
month = {Wed Mar 12 00:00:00 EDT 2008}
}