Language：English   Publishing type：Research paper (scientific journal)   Publisher：Digest of Technical Papers - IEEE International Conference on Consumer Electronics  

This paper presents the method to evaluate the fast neutron energy spectrum under mixed radiation field using the single crystal CVD diamond detector. The pulse shape discrimination based on the shape and width of the pulse was applied to extract the event in which fast neutron hits at a specific depth of the single crystal diamond. Unfolding of the measured energy deposition spectrum induced by extracted pulses could deduce the neutron energy spectrum. An experiment using 14.1 MeV mono-energetic neutron source demonstrated the reliable capability of this method to evaluate the neutron energy spectrum quantitatively.

DOI： 10.1109/ICCE59016.2024.10444274

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Materials Science: Materials in Electronics  

The glow curve components and thermoluminescence (TL) parameters of BeO ceramics plates with high bioequivalence were analyzed using extremely slow heating rates. Thermalox 995 was used as the BeO ceramic plates, which is a material with a BeO content of 99.5% or higher. The size of the plates was 10 × 10 × 0.7 mm3 with a density of 2.85 g/cm3, and an effective atomic number of 7.13. A linear accelerator was used for irradiation of the BeO plates at 5 Gy of 6 MV X-rays. After irradiation, the TL glow curve was measured using an in-house developed measurement instrument; the TL intensity was recorded from 50 to 400 °C with heating rates of 0.133, 0.05, and 0.005 °C/s used in three patterns. General-order kinetics were used for the theoretical analysis, which takes recapture into account. After irradiation, post-annealing was performed in the range of 50 to 350 °C at 50 °C intervals, and component analysis of the glow curves was also performed. The TL parameters were calculated from glow curves measured up to a heating rate that was three orders of magnitude slower than that previously measured. The activation energy and frequency factor for the main glow component at low temperatures were 1.15 eV and 1.11 × 1011/s, respectively, while those for the main glow component at high temperatures were 1.74 eV and 8.65 × 1013/s. The glow peak for the BeO ceramic plates were also determined have a low TL intensity component in close proximity to these two glow components. Furthermore, an increase in TL efficiency was observed when the glow curve was measured using an extremely slow heating rate. This may be due to a change of the carriers from TL-inactive when the glow curve is measured with a fast heating rate to TL-active with a longer thermal excitation time.

DOI： 10.1007/s10854-023-11378-7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fusion Engineering and Design  

The study aimed to develop a technique for measuring the 6Li burn-up rate using a single crystal diamond (SCD) detector (SDD) made by chemical vapor deposition (CVD) with a thin lithium fluoride foil. The method relied on pulse shape discrimination (PSD) to separate pulses by nuclear reaction products of 6Li from pulses due to fast neutrons and gamma-rays. By applying the PSD method, the rectangular shape pulses induced by events occurred at the specific depth positions of the SCD, i.e., the incident surface, the ballistic center region (BCR), and the rear surface, were extracted. Thereafter, pulses occurred each specific depth position of the SCD were discriminated according to the pulse width. Due to a short range of nuclear reaction products in the SCD, pulses at the incident surface should be induced by both fast neutrons and nuclear reaction products, although pulses at the BCR are caused by fast neutron only. The study demonstrated that quantitative measurements of nuclear reaction products in the 6Li burn-up reaction under fast neutron irradiation can be achieved using only one SDD by analyzing event rates at the incident surface and in the BCR region.

DOI： 10.1016/j.fusengdes.2023.113799

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.nima.2022.167636

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.nima.2022.112976

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.35848/1347-4065/ac971e

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.nima.2022.167414

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Language：Japanese   Publishing type：Research paper (scientific journal)  

In boron neutron capture therapy (BNCT), neutrons and γ-rays cause different biological effects, and it is necessary to discriminate between them for treatment planning and periodic inspections. Currently, the BeO powder thermoluminescence dosimeter (BeO powder TLD) is used for γ-ray dosimetry in mixed neutron and γ-ray fields due to the small capture cross section for neutrons, but correction is required because of the effects of neutron-induced activation. Besides, sales of BeO powder TLDs have been discontinued because the highly toxic BeO is readily dispersed when the detector is damaged. Therefore, the development of alternative replacement technologies for BeO powder TLDs that are not affected by neutrons is an important issue. In this study, we investigated the measurement of the γ-ray dose during BNCT using a BeO ceramic TLD, whereby the BeO was not released into the air. After 5, 15, 30, and 60 min of irradiation using the Kyoto University Research Reactor, the amount of thermoluminescence (TL) from the BeO ceramic TLD was shown to increase with irradiation time. In addition, the γ-ray dose, which was derived by converting the amount of TL to the dose, showed excellent proportionality to the irradiation time and was found to be comparable to the γ-ray dose measured with a BeO powder TLD. These results demonstrated that the BeO ceramic TLD can selectively measure only the γ-ray dose without influence by neutrons. Thus, our approach represents a new γ-ray dose measurement strategy that does not require correction for the contribution from thermal neutrons.

DOI： 10.1007/s10854-022-08843-0

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Publishing type：Research paper (scientific journal)  

DOI： 10.3390/jne3030012

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Plasma Science and Nuclear Fusion Research  

<p>Neutrons are generated in a fusion plasma and induce various radionuclides via a nuclear reaction with fusion reactor materials. Evaluating the kinds of nuclide and the amount of induced radioactivity is important for decommissioning planning and regular maintenance. In this study, we verified a long-term prediction model of induced radioactivity in the large helical device (LHD) model by comparing induced radioactivity generated during deuterium plasma experiments in LHD with results calculated using a high-energy particle-induced radioactivity code. The metals employed for activation were SUS316L, Co, Mo, and Ni. During the deuterium plasma experiments, these materials were placed on an 8-O port of the LHD, and the induced radioactivity was measured weekly. To computed induced radioactivity using DCHAIN-SP, the neutron energy spectrum was computed using the LHD model with the Monte-Carlo simulation code PHITS. Although the calculated and measured radioactivity of ⁵⁸Co and ⁵⁴Mo agreed well, the calculated values of ⁶⁰Co and ⁹⁹Mo were underestimated. However,low-energy components could be improved by incorporating peripheral devices into the LHD model, resulting in more accurate radioactivity predictions.</p>

DOI： 10.1585/pfr.17.2405096

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CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.35848/1347-4065/ac7273

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Plasma Science and Nuclear Fusion Research  

<p>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 7.6×10⁶n cm⁻²s⁻¹W⁻¹up to a reactor power of 1 W.</p>

DOI： 10.1585/pfr.17.2405045

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CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.fusengdes.2022.113117

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1080/00223131.2021.1996297

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/00223131.2021.1981475

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Language：Japanese   Publishing type：Research paper (scientific journal)  

An optical fiber-based neutron detector can be used as a real-time neutron monitor for an intense neutron field. In this study, optical fiber-based neutron detectors were fabricated using Li-glass scintillator. The thermal neutron sensitivity, upper limit of the output linearity, and response to gamma rays from 60Co and Cd were evaluated. The thermal neutron sensitivity was proportional to the mass of the Li-glass scintillator, and the calibration factor was 2.06 × 10−6 and 3.18 × 10−6 cps/(n/cm 2/s)/μg for the lower-level discrimination of the peak and valley channel, respectively. The detector output linearity was confirmed to be up to nearly 2 Mcps. While evaluating the response to gamma rays, for both 60Co and Cd, the gamma-ray counting rate was found to be smaller than the uncertainty associated with counting statistics in most expected applications where the neutron counting rate was >1 kcps.

DOI： 10.1016/j.nima.2021.166074

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Plasma Science and Nuclear Fusion Research  

<p>An accelerator-based neutron source using d-Li reactions is one of the most promising neutron sources for fusion material irradiation facilities such as IFMIF, where 40 MeV deuterons bombard a liquid lithium target. The neutron yield estimation including angular neutron spectra is one of the most important issues in the design of such irradiation facilities. Recently, JAEA released deuteron nuclear data of JENDL/DEU-2020 in ACE format file for Monte Carlo codes such as MCNP, and in Frag-Data format for the PHITS code. We carry out the benchmark calculations of d-Li neutron yield by using PHITS with Frag-Data, MCNP with JENDL/DEU-2020, and MCNP/PHITS with built-in nuclear reaction models. Those calculation results are compared with experimental data. It is confirmed that PHITS with Frag Data and MCNP with JENDL/DEU-2020 reproduce well the experimental data. Those are useful for the neutron yield estimation and also the irradiation field characterization of IFMIF and similar facilities.</p>

DOI： 10.1585/pfr.16.1405104

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CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2021.1.0_576

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2021.1.0_576

Language：English   Publishing type：Research paper (scientific journal)  

As the commissioning phase of the Nagoya University Accelerator-driven Neutron Source for boron neutron capture therapy, in-phantom thermal neutron flux measurements were conducted using a small ^<6>LiF/Eu:CaF_2 scintillator detector and activation foils. The spatial distribution of the measured thermal neutron flux agreed with the Monte Carlo simulation results. Based on this comparison, the free-in-air neutron spectrum, calculated at the exit aperture, was verified and the epithermal neutron flux, at a 0.25 mA proton current, was evaluated as (1.49±0.10)×10^<7> n/(c㎡ s).

DOI： 10.1016/j.apradiso.2020.109553

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PubMed

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

The Pulse shape discrimination (PSD) technique for single crystal CVD diamond detector (SDD) was applied to the real-time thermal neutron measurement during the 3rd campaign of Deuterium-Deuterium (D-D) plasma experiment in the Large Helical Device (LHD). The PSD method is based upon the different shape of electrical pulses produced in diamond by gamma-ray (triangular-shaped pulse) and energetic ions (rectangular-shaped pulse), respectively. An improved PSD was developed which makes use of the full width at half maximum (FWHM) and the full width at 2/3 of the peak height (FW2/3 PH). These two parameters reflect the difference in the pulse shape produced by gamma-rays and energetic ions. The performance of this improved PSD technique was first tested irradiating the SDD by gamma-rays from 60Co and alphas from 241Am radiation sources, respectively. Then, using a 6LiF thermal neutron converter, a successful discrimination between gamma-rays and alpha particles and tritons generated by the 6Li(n,α)3H reaction induced by neutrons from 252Cf spontaneous fission neutron source was achieved. Thanks to this PSD processing technique, the thermal neutron detection efficiency increased about 1.7 times compared to previous measurements performed without the PSD technique. The real-time thermal neutron measurement by SDD with this enhanced PSD processing was also used during D-D plasma discharges in the Large Helical Device (LHD). It was found that both the time integrated counts and the time evolution count rate measured by the SDD reproduced well that of the fission chamber used as official LHD neutron monitor. The capability of the SDD detector using the PSD technique of precise real-time thermal neutron measurement in LHD was demonstrated.

DOI： 10.1016/j.fusengdes.2020.112063

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI  

Boron neutron capture therapy (BNCT) requires pharmaceutical innovations and molecular-based evidence of effectiveness to become a standard cancer therapeutic in the future. Recently, in Japan, 4-borono-L-phenylalanine (BPA) was approved as a boron agent for BNCT against head and neck (H&N) cancers. H&N cancer appears to be a suitable target for BPA-BNCT, because the expression levels of L-type amino acid transporter 1 (LAT1), one of the amino acid transporters responsible for BPA uptake, are elevated in most cases of H&N cancer. However, in other types of cancer including malignant brain tumors, LAT1 is not always highly expressed. To expand the possibility of BNCT for these cases, we previously developed poly-arginine peptide (polyR)-conjugated mercaptoundecahydrododecaborate (BSH). PolyR confers the cell membrane permeability and tumor selectivity of BSH. However, the molecular determinants for the properties are not fully understood. In this present study, we have identified the cluster of differentiation 44 (CD44) protein and translational machinery proteins as a major cell surface target and intracellular targets of BSH-polyR, respectively. CD44, also known as a stem cell-associated maker in various types of cancer, is required for the cellular uptake of polyR-conjugated molecules. We showed that BSH-polyR was predominantly delivered to a CD44(High) cell population of cancer cells. Once delivered, BSH-polyR interacted with the translational machinery components, including the initiation factors, termination factors, and poly(A)-biding protein (PABP). As a proof of principle, we performed BSH-polyR-based BNCT against glioma stem-like cells and revealed that BSH-polyR successfully induced BNCT-dependent cell death specifically in CD44(High) cells. Bioinformatics analysis indicated that BSH-polyR would be suitable for certain types of malignant tumors. Our results shed light on the biochemical properties of BSH-polyR, which may further contribute to the therapeutic optimization of BSH-BNCT in the future.

DOI： 10.3390/cells9102149

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PubMed

Language：Japanese   Publishing type：Research paper (scientific journal)  

Neutron emission anisotropy caused by neutral beam injection was observed by the neutron activation measurement in deuterium plasmas confined in the Large Helical Device. The shot-integrated fast neutron flux was measured by the irradiation of activation foils at two irradiation ends located at different ports. The ratio of the flux at the outside horizontal port to that at the lower port was used as an index of neutron emission anisotropy. The dependence of the ratio on the direction of the neutral beam injection was confirmed by comparing cases of tangential, perpendicular and both tangential and perpendicular neutral beam injections. Neutron emission anisotropy was numerically evaluated assuming these three cases of neutral beam injection. The analysis of neutron emission anisotropy comprises the evaluation of the velocity distribution function of energetic deuterons following guiding-centre orbits, calculation of the double-differential emission spectrum of neutrons produced by the D(d,n) 3&rm He reaction and neutron transport calculation. The obtained numerical results are qualitatively consistent in the dependence of neutron emission anisotropy on the neutral-beam-injection direction with the observed experimental data.

DOI： 10.1088/1741-4326/ab90c9

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Radiation Measurements  

BNCT is a radiation therapy using neutrons. For dosimetry in BNCT, it is important to evaluate the thermal neutron distribution in a water phantom irradiated with neutrons used in the therapy. We proposed application of a small 6Li-based scintillator neutron detector with an optical fiber into a comparison study between simulation and experimental results in BNCT. In this paper, we compared simulation and experimental results for depth profile of 6Li(n,α) reaction rate in a water phantom of BNCT using a developed small 6Li-based scintillator neutron detector. The experimental results well agreed with the simulation ones. However, we found that the self-shielding effect in the detector will be significant even for a small LiF/Eu:CaF2 eutectics scintillator having the mass of 100 μg. We concluded that we have to consider the self-shielding effect in the small 6Li-based scintillator neutron detector when comparing simulation and experimental results of the 6Li(n,α) reaction rate in a water phantom.

DOI： 10.1016/j.radmeas.2020.106270

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2020.1.0_555

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2020.1.0_555

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.nima.2018.09.079

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.nima.2018.11.120

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Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmetokai.2020.69.520

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Plasma Science and Nuclear Fusion Research  

<p>The designs of neutron spectrum-shaping assembly (NSSA) composed with various shielding materials with natural isotopic abundance were evaluated to construct the neutron field dominated with thermal neutron or epi-thermal neutron for the application of neutron filed in the torus hall of LHD toward the BNCT research. According to the neutron transport calculation by MCNP6, the fast neutron moderation efficiency was higher in polyethylene (PE) compared to lithium fluoride (LiF) and magnesium fluoride (MF), although LiF showed relatively large epi-thermal and thermal neutron absorption. This comparison showed that the thermal neutron field can be effectively achieved with using PE. For constructing the NSSA which can provide the neutron field dominated with epi-thermal neutron, several NSSA designs were evaluated with respect to fast neutron flux, epi-thermal neutron flux, and gamma-ray dose. The combination of MF, lead (Pb) and cadmium (Cd) can provide the good epi-thermal neutron field with the mitigations of fast neutron flux and gamma-ray dose, which is also suitable for BNCT research in the torus hall of LHD.</p>

DOI： 10.1585/pfr.15.2405043

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CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Sensors and Materials  

The development of a neutron detector for real-time measurements in an intense neutron field is desired. We are developing a quartz optical-fiber-based neutron detector as a real-time neutron monitor. Thus far, Eu:LiCaAlF6 crystals and LiF/Eu:CaF2 eutectics have been used as the scintillators of the quartz optical-fiber-based neutron detectors. These scintillators have high light yields, but relatively long decay time constants, which are the limiting factors for the dynamic range of optical-fiber-based neutron detectors. In this work, we applied a small Li glass scintillator to a quartz optical-fiber-based neutron detector using an optical fiber with high numerical aperture and a UV-curable resin with high transmittance. The fabricated detector showed a clear peak corresponding to neutron events in the pulse height distribution. The radiation resistance was evaluated and no deterioration was observed up to 2 × 1012 n/cm2. The detector output linearity was confirmed up to 450 kcps, which was about ten times larger than that of the detector using the conventional Eu:LiCaAlF6 or LiF/Eu:CaF2 scintillator.

DOI： 10.18494/SAM.2020.2748

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2019.2.0_519

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2019.2.0_519

Language：Japanese   Publishing type：Research paper (scientific journal)  

A single crystal CVD diamond detector (SDD) was installed in the torus hall of the Large Helical Device (LHD) to measure neutron during deuterium plasma operation. The LiF foil with 95.62% of 6Li isotope enrichment pasted on the detector was used as the thermal neutron convertor. The energetic ions of 2.0 MeV alpha and 2.7 MeV triton particles generated by the nuclear reaction of neutron with 6Li in LiF foil. Then, energetic ions deposited the energy into diamond, producing a signals in SDD. SDD were exposed to the neutron field in the torus hall of the LHD during the 2nd campaign of the deuterium experiment. The total charge in SDD during one plasma shot in LHD was linearly propotional to the neutron yield over 4 orders of magnitude. The energetic alpha and triton were separately measured by SDD with LiF with the thickness of 1.9 μm, although SDD with LiF with the thickness of 350 μm showed a broadened peak due to the large energy loss of energetic particles generated in the bulk of LiF. The modeling with MCNP and PHITS codes well interpreted the pulse height spectra for SDD with LiF with different thicknesses.

DOI： 10.1088/1748-0221/14/09/C09039

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.1088/1748-0221/14/06/T06010

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Other Link： https://iopscience.iop.org/article/10.1088/1748-0221/14/06/T06010

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2019.1.0_561

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2019.1.0_526

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Atomic Energy Society of Japan  

We have developed the single sphere neutron spectrometer with five sensitive layers using the TRUST Eu:LiCAF scintillator and the WLSF readout. We evaluated the energy dependence of the detector response at thermal neutron and 24 keV, 144 keV, 565 keV, 5MeV and 14.8 MeV mono-energetic neutron irradiation fields. The experimentally determined neutron sensitivities are consistent with the Monte Carlo calculations. The detector responses for a bare and a heavy-water moderated 252Cf sources also show good agreement with the expected ones using the Monte Carlo calculations.

DOI： 10.15669/pnst.6.122

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Atomic Energy Society of Japan  

We fabricated the hybrid type optical fiber based dosimeter system using Eu:BaFBr and Ce:CaF2 optically stimulated luminescence (OSL) materials in order to correct the quenching effect under high LET particle irradiation. The fabricated dosimeter probe can obtain signals from both OSL materials through one optical fiber. We investigated the probe response by irradiating it with mono-energetic carbon ions and broad-spectrum ones making the spread-out Bragg peak (SOBP). We demonstrated that the SOBP shape can be improved by correction of the quenching effect using the relationship between the luminescence efficiency and the signal intensity ratio of both OSL materials.

DOI： 10.15669/pnst.6.238

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Atomic Energy Society of Japan  

The application of imaging plate (IP) method using indium foils to measure the distribution of fast neutron in large area was evaluated in this work. The radioactive nuclides of indium were individually quantified by high-purity germanium detector (HPGe) and chronological IP measurements. The detection efficiencies of each radioactive nuclide for various thicknesses of foil mylar polyester film were summarized. The scope of application for proposed method were clearly dependent on the flux ratio of fast and thermal neutron, limiting the applicable region only being close to the neutron source.

DOI： 10.15669/pnst.6.58

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Plasma Science and Nuclear Fusion Research  

<p>In the Large Helical Device (LHD) of the National Institute for Fusion Science, a deuterium plasma experiment was performed in March 2017. Neutrons with an energy of 2.45 MeV are generated by d (d, n) ³He reactions. The evaluation of this neutron flux in the torus hall, as well as within the LHD vessel, is very important for the decommissioning of the LHD in the future and the radiation shielding for workers and components around the LHD. In this study, we evaluate the spatial distribution of thermal and epithermal neutron flux on the floor level of the LHD torus hall by measuring the neutron activation of gold foils. The flux information obtained in the experiment can be used for the evaluation of radio-activation and the shielding design.</p>

DOI： 10.1585/pfr.14.3405162

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CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

<p>A numerical study has been conducted to examine turbulent flow and heat transfer characteristics in a three-dimensional square-duct with V-shaped ribs. The computations are based on RANS and LES models. Water is the working fluid with the flow rate of which Reynolds numbers equals to 18500. The computation reveals that two symmetrical fully developed helical flow and developed heat transfer profile are generated. Effects of different rib shape on thermal characteristics for a ribbed duct flow are investigated. The change of the shape leads to increase in heat transfer and pressure loss. The velocity profile in the vicinity of ribs and streamline has been investigated, indicates that the different flow structures generated by the rib shape leads to superior heat transfer performance. Vortices are visualized, which indicates the connection between the heat transfer and flow structure</p>

DOI： 10.1299/jsmefed.2019.os8-07

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

For the estimation of the neutron field generated by deuterium plasma operation in the Large Helical Device (LHD), the first measurement of the thermal neutron distribution on the floor level of the LHD torus hall was carried out. For the thermal neutron detection, indium was used as activation foils. The radioactivity of these foils were evaluated by a high-purity germanium detector (HPGe) and an imaging plate (IP). The major components of radioactive isotope of indium was 116mIn. The mapping of thermal neutron distribution in the torus hall was performed. The interactions between neutron and components around LHD were observed in the thermal neutron distribution. Also, the borated polyethylene blocks effectively absorbed the thermal neutron. The thermal neutron distribution evaluated in this work can be helpful to predict the amount of radioactive waste in the torus hall proceeding with deuterium experiment in LHD.

DOI： 10.1016/j.fusengdes.2018.09.013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of the Physical Society of Japan  

DOI： 10.7566/jpscp.22.011003

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

Prior to the deuterium experiments of the Large Helical Device (LHD), an in situ neutron calibration experiment was carried out by using an 800 MBq 252Cf neutron source in November 2016, where a neutron flux monitor, a neutron activation system and a vertical neutron camera are calibrated. This paper concentrates on the in situ calibration for the neutron flux monitor. The neutron flux monitor based on 235U fission chambers and 10B and 3He proportional counters are positioned at three locations outside the LHD cryostat. The counts are measured during continuous rotation of the 252Cf neutron source on the typical magnetic axis of the plasma by a toy train, where the neutron source can be regarded as a ring neutron source. Detection efficiencies for the 252Cf ring source are derived by (total counts)/(total emitted neutron number) in the continuous rotation of the neutron source. Detection efficiencies for the real plasma neutron source are obtained from the measured detection efficiencies with the correction factor taking account of the deference between the 252Cf ring source and the real plasma neutron source evaluated by MCNP calculations with the three-dimensional model of the LHD. Finally, the uncertainty of the total neutron emission rate measurement is discussed.

DOI： 10.1016/j.fusengdes.2018.01.053

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Language：Japanese   Publishing type：Research paper (scientific journal)  

The deuterium operation of the large helical device (LHD) began in March 7, 2017, after long-term preparation and commissioning of apparatuses necessary for execution of the deuterium experiment. A comprehensive set of neutron diagnostics was developed and installed onto LHD through numerous efforts in preparation. Neutron diagnostics play an essential role in both neutron yield management for the radiation safety and extension of energetic-particle physics study in LHD. Neutron flux monitor (NFM) characterized by fast-response and wide dynamic range capabilities is successfully working. Total neutron emission rate reached $3.3 \times 10^{15}$ (n/s) in the first deuterium campaign of LHD. The highest neutron emission rate was recorded in inward shifted configuration. Neutron yield evaluated by neutron activation system agrees with neutron yield measured with NFM. Performance of vertical neutron camera was demonstrated. Neutron emission profile was inwardly shifted in the inwardly shifted configuration, whereas it was outwardly shifted in the outwardly configuration. Secondary deuterium-tritium neutrons produced by triton burnup in LHD deuterium plasmas were detected for the first time in stellarator/heliotron devices in the world. Similar to total neutron emission rate, the inward shifted configuration provided highest triton burnup ratio.

DOI： 10.1109/TPS.2018.2836987

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Atomic Energy Society of Japan  

DOI： 10.3327/jaesjb.60.5_303

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

In situ calibration of the neutron activation system on the Large Helical Device (LHD) was performed by using an intense 252Cf neutron source. To simulate a ring-shaped neutron source, we installed a railway inside the LHD vacuum vessel and made a train loaded with the 252Cf source run along a typical magnetic axis position. Three activation capsules loaded with thirty pieces of indium foils stacked with total mass of approximately 18 g were prepared. Each capsule was irradiated over 15 h while the train was circulating. The activation response coefficient (9.4 ± 1.2) × 10-8 of 115In(n, n′)115mIn reaction obtained from the experiment is in good agreement with results from three-dimensional neutron transport calculations using the Monte Carlo neutron transport simulation code 6. The activation response coefficients of 2.45 MeV birth neutron and secondary 14.1 MeV neutron from deuterium plasma were evaluated from the activation response coefficient obtained in this calibration experiment with results from three-dimensional neutron calculations using the Monte Carlo neutron transport simulation code 6.

DOI： 10.1063/1.5009475

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Scopus

PubMed

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.fusengdes.2017.03.111

Web of Science

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2017.2.0_453

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：MYU, SCIENTIFIC PUBLISHING DIVISION  

To monitor an actual dose in a patient's body during radiotherapy treatment, we have developed a small-size dosimeter of an optical fiber probe mounting optically stimulated luminescence (OSL) materials at the tip. The OSL materials show a quenching effect when they are irradiated by charged particles with high linear energy transfer (LET). We evaluate the particle dependence on the quenching effect in the small-size OSL dosimeter probe. Eu:BaFBr and Ce:CaF2 were adopted as OSL materials, and two types of small-size dosimeter were fabricated. We irradiated 290 MeV/u carbon ions, 150 MeV/u helium ions, and 225 MeV protons and measured the Bragg peak. The Eu:BaFBr small-size dosimeter showed the quenching effect in these three types of particle irradiation. The Ce:CaF2 small-size dosimeter showed the quenching effect only in carbon ion irradiation. The luminescence efficiencies of Eu:BaFBr were compared among these three charged particles. The quenching effect of Eu:BaFBr is independent of the irradiated particles.

DOI： 10.18494/SAM.2017.1626

Web of Science

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Proceedings of Science  

The Nagoya University Accelerator driven Neutron Source (NUANS) are now constructing at main campus of Nagoya University. The electrostatic accelerator is used with the maximum proton energy and power of 2.8MeV, 15mA(42kW) respectively. Two neutron beam lines are planned at NUANS. The first beam line is dedicated to BNCT. The second beam line is designed for research and development of neutron devices and neutron imaging. The neutrons used for the 2nd beam line are generated by using the (p, n) reaction of beryllium. We designed a compact target station for the 2nd beam line with the dimension of 90cm×90cm×95cm by using radiation shielding simulation. We considered neutron beam extraction with the cross section of 10cm×10cm for radiography at the 2nd beam line. The neutron flux is expected to be about 104n cm-2s-1 with the energy less than 0.1 eV at the position of 2m from the neutron source. We also calculated the proton beam transport from the exit of the accelerator to the neutron production target of the 2nd beam line.

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Proceedings of Science  

The Nagoya University Accelerator driven Neutron Source (NUANS) are now constructing at main campus of Nagoya University. The electrostatic accelerator is used with the maximum proton energy and power of 2.8MeV, 15mA(42kW) respectively. Two neutron beam lines are planned at NUANS. The first beam line is dedicated to BNCT. The second beam line is designed for research and development of neutron devices and neutron imaging. The neutrons used for the 2nd beam line are generated by using the (p, n) reaction of beryllium. We designed a compact target station for the 2nd beam line with the dimension of 90cm×90cm×95cm by using radiation shielding simulation. We considered neutron beam extraction with the cross section of 10cm×10cm for radiography at the 2nd beam line. The neutron flux is expected to be about 104n cm-2s-1 with the energy less than 0.1 eV at the position of 2m from the neutron source. We also calculated the proton beam transport from the exit of the accelerator to the neutron production target of the 2nd beam line.

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.nme.2016.05.012

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1585/pfr.11.1405117

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Mock-up experiment for development of accelerator based neutron source for Osaka University BNCT project was carried out at Birmingham University, UK. In this paper, spatial distribution of neutron flux intensity was evaluated by foil activation method. Validity of the design code system was confirmed by comparing measured gold foil activities with calculations. As a result, it was found that the epi-thermal neutron beam was well collimated by our neutron moderator assembly. Also, the design accuracy was evaluated to have less than 20% error.

DOI： 10.1016/j.apradiso.2015.07.037

Scopus

PubMed

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.apradiso.2015.07.026

PubMed

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Authorship：Lead author  

Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Publishing type：Research paper (scientific journal)  

Authorship：Lead author  

Authorship：Lead author  

Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

CiNii Books

DOI： 10.11470/jsapmeeting.2020.1.0_555

Language：English  

DOI： 10.1299/jsmetokai.2020.69.520

DOI： 10.11470/jsapmeeting.2019.2.0_519

Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2019.1.0_526

CiNii Research

Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2019.1.0_561

CiNii Research

Language：English  

Language：English  

Language：Japanese  

CiNii Books

Language：Japanese  

CiNii Books

Language：Japanese  

CiNii Books

Language：Japanese  

CiNii Books

Language：Japanese  

CiNii Books

Event date： 2021.11

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.11

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.9

Presentation type：Oral presentation (general)  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2021.9

Presentation type：Oral presentation (general)  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2021.9

Presentation type：Oral presentation (general)  

Event date： 2021.3

Event date： 2021.3

Event date： 2021.3

Presentation type：Oral presentation (general)  

Event date： 2021.3

Presentation type：Oral presentation (general)  

Event date： 2021.3

Presentation type：Oral presentation (general)  

Event date： 2021.3

Presentation type：Oral presentation (general)  

Event date： 2021.3

Presentation type：Oral presentation (general)  

Event date： 2021.3

Presentation type：Oral presentation (general)  

Event date： 2020.11 - 2020.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Online  

Event date： 2020.9

Language：English   Presentation type：Poster presentation  

Venue：Online  

Event date： 2020.9

Event date： 2020.9

Presentation type：Oral presentation (general)  

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2020.9

Presentation type：Oral presentation (general)  

Event date： 2020.9

Presentation type：Oral presentation (general)  

Event date： 2020.9

Presentation type：Oral presentation (general)  

Event date： 2020.9

Presentation type：Oral presentation (general)  

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2020.9

Presentation type：Oral presentation (general)  

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2020.9

Presentation type：Oral presentation (general)  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

DOI： 10.1088/1748-0221/14/09/C09039

Scopus

Event date： 2018.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.9

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2017.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.7

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.7

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2017.7

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2017.6

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.4

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017

Language：English   Presentation type：Oral presentation (general)  

Scopus

Event date： 2016.9

Language：English   Presentation type：Poster presentation  

Country：Czech Republic  

Event date： 2014.9 - 2014.10

Language：English   Presentation type：Poster presentation  

Country：Spain  

Event date： 2014.8 - 2014.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2014.6

Language：English   Presentation type：Poster presentation  

Country：Finland  

Event date： 2013.12

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2013.4

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Audience： High school students

Type：Lecture