Accelerator-based Neutron Fluence Standard of the National Metrology Institute of Japan

Harano, Hideki; Matsumoto, Tetsuro; Nishiyama, Jun; Uritani, Akira; Kudo, K.

doi:10.1063/1.3120189

Cited by 21 publications

(10 citation statements)

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“…The neutron emission rates were calibrated for the Am-Be source by the manganese bath method at NPL [15] and for the Cf source by a method using the graphite pile at NMIJ [16]. Monoenergetic neutrons were produced at 144 keV and 565 keV by the Li(p,n) Be reaction and at 5 MeV by the D(d,n) He reaction with a Van de Graaff accelerator and at 14.8 MeV by the T(d,n) He reaction with a Cockcroft-Walton accelerator [17]. The accuracy of the neutron fluences provided at 144 keV, 5 MeV, and 14.8 MeV were supported by the recent international comparison performed by the Consultative Committee for Ionizing Radiation (CCRI) of the International Bureau of Weights and Measures (BIPM) [18].…”

Section: Methodsmentioning

confidence: 99%

Development of a Compact Flat Response Neutron Detector

Harano

Matsumoto

Nishiyama

et al. 2011

IEEE Trans. Nucl. Sci.

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Long counters are widely used as neutron fluence monitors for their flat response. However, a bulky neutron moderator is required to achieve the flat response, which can be a disadvantage for portability and an undesirable source of scattered neutrons. Reducing the size of the moderator degrades the flat response, especially for high-energy neutrons. We propose a new method to reduce the size of the moderator while keeping a flat response, and we develop a compact flat-response neutron detector. The detector consists of two small spherical 3 He proportional counters embedded at appropriate positions in a compact cylindrical polyethylene moderator. The sensitivity ratio between the two counters was adjusted to provide a flat response in the total outputs from the two counters. We demonstrated by MCNPX calculations and response measurements for Cf and Am-Be neutrons and monoenergetic neutrons that the present detector had a sensitivity comparable to long counters with a good flat response in a wide energy range up to 20 MeV while being only one-fifth of the weight of long counters. The positions of the effective center were determined as a function of neutron energy. We also proposed a method to evaluate the neutron energy using the detector, which will allow various new applications taking advantage of the ability to measure neutron fluence and energy at the same time.Index Terms-Effective center, flat response, long counter, neutron energy evaluation, neutron fluence measurement.

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Section: Methodsmentioning

confidence: 99%

Development of a Compact Flat Response Neutron Detector

Harano

Matsumoto

Nishiyama

et al. 2011

IEEE Trans. Nucl. Sci.

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“…The neutron emission rates were calibrated for the Am-Be source by the manganese bath method at NPL [13] and for the Cf source by the method using the graphite pile at NMIJ [14]. Monoenergetic neutrons were produced at 144 keV, 565 keV and 5 MeV with a Van de Graaff accelerator and at 14.8 MeV with a Cockcroft Walton accelerator [15]. The accuracy of the neutron fluences provided at 144 keV, 5 MeV and 14.8 MeV were supported by the recent international comparison organized by the Consultative Committee for Ionizing Radiation (CCRI) of the International Bureau of Weights and Measures (BIPM) [16].…”

Section: Methodsmentioning

confidence: 99%

Development of a compact flat response neutron detector

Harano

Matsumoto

Nishiyama

et al. 2010

IEEE Nuclear Science Symposuim &Amp; Medical Imaging Conference

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Long counters are widely used as neutron fluence monitors by utilizing their flat-response feature. A bulky neutron moderator is required however to achieve the flatresponse feature, which can be a disadvantage from the viewpoint of portability as well as an undesirable source of scattered neutrons. Just downsizing the moderator deteriorates the flat response especially for high-energy neutrons. We proposed a new method to downsize the moderator with keeping the flat-response feature and developed a compact flat-response neutron detector in the present study. The detector consists of two small spherical 3 He proportional counters embedded in appropriate positions in a compact cylindrical polyethylene moderator. The sensitivity ratio between the two counters was adjusted to provide a flat response in the total outputs from the two counters. It was demonstrated by MCNPX calculations and response measurements for Cf and Am-Be neutrons and monoenergetic neutrons that the present detector had a good flat response in the wide energy range up to 20 MeV while being downsized by one fifth compared with long counters. The positions of the effective center were determined as a function of the neutron energy. We also proposed a method to evaluate the neutron energy using the detector, which will allow various new applications by taking advantage of measuring the neutron fluence and energy at the same time.

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“…In particular, fusion reactions can generate neutrons with monochromatic energy, and therefore they are often used to calibrate detectors. In this study, the following two types of fusion reactions (endothermic reactions, whose targets are lithium and tritium) provided by the National Institute of Advanced Industrial Science and Technology (AIST) as the standard neutron field [17] were used to verify the detection of 3/16 monochromatic neutrons with sub-MeV energy:…”

Section: Monochromatic Sub-mev Neutron Exposurementioning

confidence: 99%

Development of New Tracking Detector with Fine-grained Nuclear Emulsion for sub-MeV Neutron Measurement

Shiraishi

Todoroki²,

Naka³

et al. 2021

Preprint

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In this study, we have developed a new sub-MeV neutron detector that has a high position resolution, energy resolution, directional sensitivity, and low background. The detector is based on a super-fine-grained nuclear emulsion, called the Nano Imaging Tracker (NIT), and it is capable of detecting neutron induced proton recoils as tracks through topological analysis with sub-micrometric accuracy. We used a type of NIT with AgBr:I crystals of (98 ± 10) nm size dispersed in the gelatin. First, we calibrated the performance of NIT device for detecting monochromatic neutrons with sub-MeV energy generated by nuclear fusion reactions, and the detection efficiency for recoil proton tracks of more than 2 µm range was consistently 100% (the 1 σ lower limit was 83%) in accordance with expectations by manual based analysis. In addition, recoil energy and angle distribution obtained good agreement with kinematical expectation. The primary neutron energy was reconstructed by using them, and it was evaluated as 42% with FWHM at 540 keV. Furthermore, we demonstrated newly developed an automatic track recognition system dedicated to the track range of more than a few micrometers. It achieved a recognition efficiency of (74 ± 4)%, and recoil energy and angle distribution obtained good agreement with manual analysis. Finally, it indicated the very high rejection power for γ-rays.

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Accelerator-based Neutron Fluence Standard of the National Metrology Institute of Japan

Cited by 21 publications

References 0 publications

Development of a Compact Flat Response Neutron Detector

Development of a Compact Flat Response Neutron Detector

Development of a compact flat response neutron detector

Development of New Tracking Detector with Fine-grained Nuclear Emulsion for sub-MeV Neutron Measurement

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