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Uchida, Yuki*; Takada, Eiji*; Fujisaki, Akihiro*; Isobe, Mitsutaka*; Ogawa, Kunihiro*; Shinohara, Koji; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*
Review of Scientific Instruments, 85(11), p.11E118_1 - 11E118_4, 2014/11
Times Cited Count:9 Percentile:38.54(Instruments & Instrumentation)Ishihara, Kohei*; Takagi, Keisuke*; Minato, Haruna*; Kawarabayashi, Jun*; Tomita, Hideki*; Maeda, Shigetaka; Naka, Tatsuhiro*; Morishima, Kunihiro*; Nakano, Toshiyuki*; Nakamura, Mitsuhiro*; et al.
Radiation Measurements, 55, p.79 - 82, 2013/08
Times Cited Count:1 Percentile:10.19(Nuclear Science & Technology)In order to measure the neutron under a condition of high intensity of -ray background, we made new nuclear emulsion based on non-sensitized OPERA emulsion which had small AgBr grain size (AgBr grain size of 60, 90 and 160 nm). The sensitivity of this new emulsion, which was a correlation between stopping power and grain density, was estimated experimentally by irradiating neutrons with several energies. We also simulated the response to -ray induced electrons and compared with some experimental results by using Co source. The results showed that there might be a threshold energy deposited in one AgBr grain under which it was impossible to develop. We estimated efficiency to the -ray and the neutron with this obtained response of the new emulsion.
Kawarabayashi, Jun*; Ishihara, Kohei*; Takagi, Keisuke*; Tomita, Hideki*; Iguchi, Tetsuo*; Naka, Tatsuhiro*; Morishima, Kunihiro*; Maeda, Shigetaka
Journal of ASTM International (Internet), 9(3), 5 Pages, 2012/03
In order to measure the neutron from a spent fuel assembly in fast breeder reactor precisely, we made new nuclear emulsion based on non-sensitized OPERA film with AgBr grain size of 60, 90 and 160 nm. The efficiency for Cf neutron of the new emulsion was calculated to be 0.710 which energy ranged from 0.3 to 2 MeV that agrees with preliminary estimated value from experimental results. The sensitivity of the new emulsion was also estimated experimentally by irradiating 565 KeV and 14 MeV neutrons and found that the emulsion with the AgBr grain size of 60 nm showed the lowest sensitivity among these three emulsions but still had enough sensitivity for proton. Also, there was a suggestion from the experimental data that there was a threshold LET of 15 KeV/m for our new emulsion below which no silver cluster was developed. Further development of the response of nuclear emulsion with a few tens of nano-meter AgBr size is next step of this study.
Asai, Keisuke*; Yukawa, Kyohei*; Iguchi, Tetsuo*; Naoi, Norihiro*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Yamauchi, Michinori*; Konno, Chikara
Fusion Engineering and Design, 83(10-12), p.1818 - 1821, 2008/12
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)The fuel ratio in a DT burning plasma can be derived from the intensity ratio of DD/DT neutrons, and detecting a trace of DD neutrons in the DT burning plasma is a key issue. A new type of neutron spectrometer is proposed to monitor the fuel ratio in the core of the ITER plasma. The system based on a conventional time-of-flight method consists of a water cell as a neutron scattering material and tens of scintillator pairs arranged around the first scintillator in a corn shape. We call it a multi-scattering time-of-flight neutron spectrometer (MS-TOF). A trial experiment was conducted for the prototype MS-TOF system with a DT neutron beam (20-mm diameter) at the Fusion Neutronics Source (FNS), Japan Atomic Energy Agency. The experimental results show that the DD and DT neutron peaks are clearly observed, and the experiment has successfully demonstrated the feasibility of the MS-TOF concept for detecting trace-DD neutrons within a DT neutron beam extracted from a DT burn plasma.
Naoi, Norihiro*; Asai, Keisuke*; Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Nishitani, Takeo
Review of Scientific Instruments, 77(10), p.10E704_1 - 10E704_3, 2006/10
Times Cited Count:5 Percentile:29.30(Instruments & Instrumentation)The high-energy-resolution neutron spectrometry is a useful method to obtain the ion temperature and velocity distribution in nuclear fusion and/or burn plasmas. For ion temperature measurement in the ITER, we propose a promising neutron spectrometer with high-energy-resolution based on the associated particle detection using a proton recoil telescope (PRT) and a time-of-flight spectrometer (TOF). In a general PRT or TOF spectrometer, uncertainty of incident angles of recoiled protons or scattered neutrons incoming to rear detector, respectively, is a cause of deterioration of their energy resolution. In this system, no angular information is required to obtain the incident neutron energy. It is possible to enlarge the solid angles of the rear detectors subtended by the radiator to increase the detection efficiency without deterioration of the energy resolution. To verify the operational principle and the basic performance of this system, we have constructed a prototype system through Monte Carlo simulations and carried out a preliminary experiment with a deuterium-tritium neutron beam at the Fusion Neutronics Source (FNS), JAEA to obtain the energy resolution around 3.3% (in FWHM) for DT neutrons. As a result of the study for the experiment, it is expected that this system can be applied to ITER at the power within 1 order of magnitude of the maximum with measurement accuracy better than 10%.
Asai, Keisuke*; Naoi, Norihiro*; Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Nishitani, Takeo
Review of Scientific Instruments, 77(10), p.10E721_1 - 10E721_3, 2006/10
Times Cited Count:3 Percentile:19.95(Instruments & Instrumentation)A time-of-flight (TOF) neutron spectrometer is one of the candidates of the measurement of the D/T burning ratio in ITER. In the ITER high power experiments, the TOF system would suffer from high event rate or accidental counts due to high radiation intensities, which can be one of background sources for DD neutron measurement. We propose a new neutron spectrometer to apply to the measurement of the D/T burning ratio in the ITER high power operation region. This system is based on the conventional double crystal TOF method and consists of a water cell and several pairs of scintillators. A water cell is inserted before the first scintillator of the TOF system and acts as a radiator or neutron scattering material. Because DD neutrons have a larger cross section of elastic scattering with hydrogen than DT neutrons, the elastic scattering in the radiator enhances the relative ratio of DD/DT intensity by about 3 times before entering the TOF system. The enhancement of the relative intensity of DD neutrons makes the detection of DD neutrons easier. The feasibility of this method as a neutron spectrometer and the basic performances of this system have been verified through a preliminary experiment using a DT neutron beam (20 mm) at the Fusion Neutronics Source, Japan Atomic Energy Agency.
Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Uritani, Akira*; Enokida, Yoichi*; Watanabe, Kazuo
JAERI-Tech 2004-010, 62 Pages, 2004/03
no abstracts in English
Tsujimura, Norio; Yoshida, T.; Kawarabayashi, Jun*; Mizuno, Ryoji*; Naka, Ryotaro*; Uritani, Akira*; Watanabe, Kenichi*
JNC TY8400 2003-010, 46 Pages, 2003/03
The authors developed a radiation distribution monitor using a normal optical fiber. This monitor has long operation length (10m - 100m) and can obtain continuous radiation distribution.
Naoi, Norihiro*; Asai, Keisuke*; Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Nishitani, Takeo
no journal, ,
The energy spectrum of the neutrons in burning plasma provides information on the ion temperature and the ion energy distributions of the fuel ions. The neutron spectroscopic technique is a useful method to obtain the ion temperature and velocity distribution in the plasma core. For ion temperature measurement in the ITER high power operation phase, we propose a promising high-energy-resolution neutron spectrometer based on the associated particle detection using a proton recoil telescope and a time-of-flight spectrometer. We have carried out a preliminary experiment with a deuterium-tritium (DT) neutron beam at the Fusion Neutronics Source (FNS), JAEA, and an energy resolution of about 3% (in FWHM) was achieved for DT neutrons.
Iwai, Haruki*; Naoi, Norihiro*; Asai, Keisuke*; Iguchi, Tetsuo*; Isobe, Mitsutaka*; Yukawa, Kyohei*; Kawarabayashi, Jun*; Konno, Chikara
no journal, ,
For ion temperature measurement in DD plasma experiments, we are developing a high energy resolution neutron spectrometer based on the associated particle detection using a proton recoil telescope and a time-of-flight spectrometer. To verify the operational principle and the basic performance of this system, we have set up a prototype system through Monte Carlo simulations and carried out a preliminary experiment with a DD neutron beam at the Fusion Neutronics Source (FNS), JAEA. The results have demonstrated that the energy resolution could be achieved around 5.0% (in FWHM) for DD neutrons
Yukawa, Kyohei*; Asai, Keisuke*; Tomita, Hideki*; Iguchi, Tetsuo*; Iwai, Haruki*; Kawarabayashi, Jun*; Konno, Chikara
no journal, ,
We are developing a new neutron spectrometer to apply to the measurement of the D/T burning ratio in the ITER high-power operation region. This system is based on the conventional double crystal TOF method and consists of a water cell and several pairs of scintillators. A water cell is inserted before the first scintillator of the TOF system and acts as a radiator or neutron scattering material. Because DD neutrons have a larger cross section of elastic scattering with hydrogen than DT neutrons, the elastic scattering in the radiator enhances the relative ratio of DD/DT intensity by approximately three times before entering the TOF system. The enhancement of the relative intensity of DD neutrons makes the detection of DD neutrons easier. The feasibility of this method as a neutron spectrometer has been verified through a preliminary experiment using a DT neutron beam (20 mm) at the Fusion Neutronics Source, Japan Atomic Energy Agency, which includes a small amount of DD neutrons.
Kawarabayashi, Jun*; Maeda, Shigetaka; Takagi, Keisuke*; Ishihara, Kohei*; Tomita, Hideki*; Morishima, Kunihiro*; Iguchi, Tetsuo*
no journal, ,
The nuclear plate has an advantage which is a feeling of an owner as outstanding spatial resolution or a multi-radiation species, though measurement is simple at power supply needlessness. By controlling the diameter of AgBr crystalline particles in a film plate by this research, the film plate composition to which ray sensitivity was reduced was tried, and it developed aiming at the neutron precision measurement under the high ray background represented on the spent-nuclear-fuel surface etc.
Takagi, Keisuke*; Ishihara, Kohei*; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*; Morishima, Kunihiro*; Maeda, Shigetaka; Matsumoto, Tetsuro*
no journal, ,
In the novel nuclear emulsion development to measurement a neutron spectrum in high -ray field, in order to control -ray sensitivity, the ArBr grains of about 100 nm of particle diameter is used. The recoil proton track induced by neutron is recorded on nuclear emulsion. The track constituted by a silver grains child standing in a row discretely is recorded. The track extraction algorithm suitable for extraction of recoil proton was developed, and the characteristic was evaluated.
Ishihara, Kohei*; Sakai, Yosuke*; Kawarabayashi, Jun*; Tomita, Hideki*; Naka, Ryuta*; Asada, Takashi*; Morishima, Kunihiro*; Nakamura, Mitsuhiro*; Maeda, Shigetaka; Iguchi, Tetsuo*
no journal, ,
In order to measure neutron spectrum in high -ray field, a new nuclear emulsion and its data-processing system are developed. This report examined the optimal development conditions about the new nuclear emulsion NGITA (Neutron-Gamma Image TrAcker). By lowering developing solution temperature to 10 C from 20 C, the sensitivity to a ray was able to be controlled to the abbreviation 1/10, with the sensitivity to a neutron maintained.
Hayashi, Shota*; Takada, Eiji*; Isobe, Mitsutaka*; Ogawa, Kunihiro*; Kawarabayashi, Jun*; Tomita, Hideki*; Iguchi, Tetsuo*; Sato, Satoshi
no journal, ,
no abstracts in English
Asai, Keisuke*; Naoi, Norihiro*; Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Nishitani, Takeo
no journal, ,
Neutron spectroscopic technique can be applied to the measurement of fuel ratio, that is, deuterium and tritium densities, in the ITER plasma core. We have been developing a new time-of-flight neutron spectrometer that has a radiator in front of a pair of crystal. The radiator has a larger cross section of elastic scattering and acts as a neutron scattering material to enhance the DD/DT ratio of neutron before entering the TOF crystal. We produced a prototype system that has a water cell, 2 cm in diameter and 5 cm in thickness, as a radiator. The system performance such as detection efficiency and energy resolution were examined through an experiment with a DT neutron beam, FNS JAEA, and the experimental results agreed with simulated results.
Kamata, Ryoga*; Hagura, Naoto*; Sato, Isamu*; Nakajima, Kunihisa; Kawarabayashi, Jun*
no journal, ,
no abstracts in English
Asai, Keisuke*; Naoi, Norihiro*; Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Konno, Chikara
no journal, ,
We have been developing a time-of-flight neutron spectrometer to measure the fuel ratio in burning plasma core. This system consists of a water cell and a pair of scintillators. The water cell is inserted before the scintillator pair. The pair of scintillators is used to measure the flight time of the scattered neutron from the water cell. Elastic scattering with hydrogen nuclei in the water cell enhances the DD/DT neutron ratio and make the detection of DD neutron easier. We have considered the system configuration by Monte Carlo simulations and clarified the expected measurement accuracy and time resolution in the upper region of the ITER DT phase. This system is expected to achieve a time resolution of a few seconds with 20% accuracy for a measurement of the intensity ratio of DD/DT neutron at the ITER full power operation.
Tomita, Hideki*; Iwai, Haruki*; Iguchi, Tetsuo*; Kawarabayashi, Jun*; Isobe, Mitsutaka*; Konno, Chikara
no journal, ,
Neutron spectrometer based on coincident counting of associated particles has been developed for deuterium plasma diagnostics on Large Helical Device (LHD) at National Institute for Fusion Science. Efficient detection of 2.5 MeV neutron with high energy resolution would achievable by coincident detection of a scattered neutron and a recoiled proton associated to a elastic scattering of incident neutron in a plastic scintillator as a radiator. Calculated neutron spectra from deuterium plasma heated by neutral beam injection indicate that the energy resolution of less than 7% is required for the spectrometer to evaluate energetic deuterium confinement. By using a prototype of the proposed spectrometer, the energy resolution of 6.3% and the detection efficiency of 3.310 counts/neutron were experimentally demonstrated for 2.5 MeV mono-energetic neutron, respectively.
Ishihara, Kohei*; Takagi, Keisuke*; Kawarabayashi, Jun*; Tomita, Hideki*; Naka, Tatsuhiro*; Asada, Takashi*; Morishima, Kunihiro*; Nakamura, Mitsuhiro*; Kuge, Kenichi*; Maeda, Shigetaka; et al.
no journal, ,
The nuclear emulsion with AgBr nano-grains has been developed for neutron detection under high -ray background. It has been demonstrated that the detection sensitivity of -rays can be well suppressed compared to that of neutrons by adjusting the size of AgBr nano-grains to deposit the energy of the secondary electrons produced by -rays below a certain threshold which can create Ag latent images.