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Journal Articles

Performance analysis of fusion nuclear-data benchmark experiments for light to heavy materials in MeV energy region with a neutron spectrum shifter

Murata, Isao*; Ota, Masayuki*; Miyamaru, Hiroyuki*; Kondo, Keitaro; Yoshida, Shigeo*; Iida, Toshiyuki*; Ochiai, Kentaro; Konno, Chikara

Journal of Nuclear Materials, 417(1-3), p.1127 - 1130, 2011/10

 Times Cited Count:2 Percentile:76.59(Materials Science, Multidisciplinary)

Nuclear data are indispensable for development of fusion reactor candidate materials. However, benchmarking of the nuclear data in MeV energy region is not sufficient even now. In the present study, benchmark performance in the MeV energy region was investigated theoretically in case of experiments by using a 14MeV neutron source. We carried out a systematical analysis for light to heavy materials. As a result, the benchmark performance for neutron spectrum was confirmed to be acceptable, while for $$gamma$$-ray it was not sufficient. This indicates it was effective to use a spectrum shifter. As a shifter beryllium had the best performance. Moreover, it was preliminarily examined whether it is really acceptable that only the spectrum before last collision is considered in the benchmark performance analysis. It was pointed out that not only the last collision but also more previous collisions should be taken into account equally in the benchmark performance analysis.

Journal Articles

Measurement of charged-particle emission double-differential cross section of fluorine for 14.2 MeV neutrons

Kondo, Keitaro; Murata, Isao*; Ochiai, Kentaro; Kubota, Naoyoshi*; Miyamaru, Hiroyuki*; Konno, Chikara; Nishitani, Takeo

Journal of Nuclear Science and Technology, 48(8), p.1146 - 1157, 2011/08

 Times Cited Count:3 Percentile:67.22(Nuclear Science & Technology)

We carried out a detailed measurement of the double-differential cross sections of fluorine for emitted protons, deuterons, tritons and $$alpha$$-particles with 14.2 MeV neutron incidence. An improved charged-particle spectrometer with a pencil DT-neutron beam furnished at the FNS facility of Japan Atomic Energy Agency enabled us to obtain precise data with a fine energy resolution in wide energy range and angular range from 15 to 150 $$^{circ}$$. The obtained data were compared with the nuclear data evaluated in JENDL-3.3 and ENDF/B-VII.0. As a result, large differences in the energy and angular distributions of emitted particles and the charged-particle production cross sections were found between the measured and evaluated data. Angular-differential cross sections for several discrete peaks corresponding to excited states of residual nuclei were extracted to discuss the reaction mechanism of charged-particle emission. The obtained data suggest that the charged-particle emission reaction of fluorine has a quite complicated mechanism where both the direct reaction process and the pre-equilibrium process contribute. The present experiment is the first simultaneous measurement of the four different kinds of charged particles and would provide useful data to confirm previous experimental data as well as to establish a nuclear reaction model of fluorine.

Journal Articles

Tracking the behavior of fusion neutrons !!; The Latest research on the double-differential cross sections

Murata, Isao*; Kondo, Keitaro; Miyamaru, Hiroyuki*; Ochiai, Kentaro

Purazuma, Kaku Yugo Gakkai-Shi, 85(11), p.762 - 773, 2009/11

In order to obtain high precision cross-section data, which is indispensable for a fusion reactor design, Osaka University has advanced the development of two of new double-differential cross-section measurement techniques for about ten years through a joint research with Japan Atomic Energy Agency (JAEA). A direct measurement of (n,2n) reaction cross-sections based on neutron emission spectra and a highly accurate charged particle emission double-differential cross-section measurement are realized by using a unique DT neutron pencil beam in the world furnished at the FNS facility of JAEA. This article plainly explains the latest result of the detailed cross-section measurements for beryllium, zirconium and fluorine as well as the outline of the measurement techniques.

Journal Articles

Direct neutron spectrum measurement to validate $$^{rm nat}$$Zr(n,2n) reaction cross-section at 14 MeV

Murata, Isao*; Shiken, Kimiaki*; Kondo, Keitaro; Matsunaka, Masayuki*; Ota, Masayuki*; Miyamaru, Hiroyuki*; Ochiai, Kentaro; Konno, Chikara; Nishitani, Takeo

Fusion Engineering and Design, 84(7-11), p.1376 - 1379, 2009/06

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Lithium zirconate, Li$$_{2}$$ZrO$$_{3}$$, is known as a candidate blanket material in a fusion reactor. According to the independent benchmark studies for zirconium by JAERI, Kyoto University and Osaka University, the neutron spectrum calculations show fairly large overestimation for most evaluated nuclear data libraries. The author's group expects that the overestimation be due to a problem of evaluation for the (n,2n) reaction, because the (n,2n) reaction cross section is not well determined experimentally. In the present study, two neutrons emitted from $$^{rm nat}$$Zr(n,2n) reaction have been measured directly to reveal the problem. As a result of measurements, the cross section obtained for energies above 1 MeV, which is the lower measurable limit energy, shows a little larger than JENDL-3.3. This is an opposite result to the benchmark analysis. However, an extrapolation for the low energy region by the evaporation spectrum with the nuclear temperature of 1 MeV brought the smaller total (n,2n) reaction cross section than JENDL-3.3, which is comparable to ENDF/B-VI. This result suggests that the discrepancies reported previously might be due to inappropriate evaluation of nuclear temperature.

Journal Articles

Preliminary spectrum shifter design for intermediate energy nuclear data benchmark experiments with DT neutrons

Ota, Masayuki*; Kondo, Keitaro; Matsunaka, Masayuki*; Miyamaru, Hiroyuki*; Murata, Isao*; Iida, Toshiyuki*; Ochiai, Kentaro; Konno, Chikara

Fusion Engineering and Design, 84(7-11), p.1446 - 1449, 2009/06

 Times Cited Count:3 Percentile:71.22(Nuclear Science & Technology)

In order to validate evaluated nuclear data libraries for fusion reactor designs, various integral benchmark experiments with DT neutrons have been carried out so far on structural and advanced blanket materials at the FNS facility of JAEA. In this study, a neutron spectrum shifter, which will be placed between a sample and the DT neutron source to moderate DT neutrons incident to the sample, was adopted in order to carry out the nuclear data benchmarking induced with several MeV neutrons effectively. In order to estimate effects of the spectrum shifter, the ratio of contribution of initial 14 MeV neutrons in leakage neutron and $$gamma$$-ray spectra was calculated for the experimental configuration at FNS with a modified MCNP-4C code. The calculations were carried out for a Li$$_{2}$$TiO$$_{3}$$ sample with a Be, LiD, or D$$_{2}$$O spectrum shifter. It was found that the Be shifter was superior to others and the contribution of initial 14 MeV neutrons varied depending on material and size of the sample and shifter. The present analysis also suggested that the Be shifter was effective for secondary $$gamma$$-ray experiments.

Journal Articles

Angle-correlated spectrum measurement for two neutrons emitted from (n,2n) reaction with the coincidence detection technique using a pencil-beam DT neutron source

Murata, Isao*; Takagi, Satoshi*; Kondo, Keitaro; Shiken, Kimiaki*; Miyamaru, Hiroyuki*; Mitsuda, Motoyuki; Maekawa, Fujio; Ochiai, Kentaro; Nishitani, Takeo

Nuclear Instruments and Methods in Physics Research A, 595(2), p.439 - 446, 2008/10

 Times Cited Count:3 Percentile:68.1(Instruments & Instrumentation)

A technique was developed to measure the angle-correlated neutron energy spectrum with the coincidence detection technique using a pencil-beam DT neutron source at the Fusion Neutronics Source (FNS) of the Japan Atomic Energy Agency (JAEA). Triple differential cross-sections of the $$^{55}$$Mn(n,2n) reaction were measured first, from which the total $$^{55}$$Mn(n,2n) reaction cross-section was deduced and compared with JENDL-3.3. The agreement was sufficient to prove the validity of the technique. With the present measuring technique, a complete measurement of a medium-heavy or heavy element such as manganese would become possible through several measurements, because the angle dependence of the emitted neutrons from it is normally weak. The technique will be a useful tool for measuring the angle-correlated neutron spectrum of light elements such as beryllium for investigation of their complicated nuclear reaction mechanism.

Journal Articles

Experimental study on breakup reaction of beryllium and carbon induced with 14-MeV neutrons based on emitted charged-particle measurements

Kondo, Keitaro; Murata, Isao*; Ochiai, Kentaro; Miyamaru, Hiroyuki*; Kubota, Naoyoshi*; Konno, Chikara; Nishitani, Takeo

Proceedings of International Conference on Nuclear Data for Science and Technology (ND 2007), Vol.1, p.407 - 410, 2008/05

Beryllium and carbon are candidate materials of fusion reactors and the $$^{9}$$Be(n,2n+2$$alpha$$) and $$^{12}$$C(n,n'+3$$alpha$$) reactions are important from engineering requirements. In order to estimate double-differential cross sections (DDX) for emitted particles, we have to accurately grasp details of the reaction mechanism. Understanding of the reaction mechanism is also interesting from a viewpoint of nuclear physics. Recently we developed a new spectrometry system with a pencil-beam DT neutron source. Using the system, we carried out detailed measurements of DDX for $$alpha$$-particles emitted from beryllium and carbon. The reaction mechanism was investigated by a Monte Carlo calculation of DDX. For the $$^{9}$$Be(n,2n+2$$alpha$$) reaction, the result suggests importance of the contribution from the $$^{9}$$Be(n,$$alpha$$)$$^{6}$$He*(Ex$$geq$$1.8MeV) reaction. For the $$^{12}$$C(n,n'+3$$alpha$$) reaction, the contribution from the $$^{12}$$C(n,$$alpha$$)$$^{9}$$Be*(Ex$$geq$$2.43MeV) reaction was appeared and its ratio was investigated to explain the shape of DDX for neutrons in lower energy.

Journal Articles

Measurement of the angle-correlated neutron spectrum for the $$^{9}$$Be(n,2n) reaction with a pencil-beam DT neutron source

Murata, Isao*; Takagi, Satoshi*; Shiken, Kimiaki*; Kondo, Keitaro; Miyamaru, Hiroyuki*; Ochiai, Kentaro; Nishitani, Takeo; Konno, Chikara

Proceedings of International Conference on Nuclear Data for Science and Technology (ND 2007), Vol.2, p.999 - 1002, 2008/05

The (n,2n) reaction plays a very important role in the design of fusion reactor. In the present study, using a pencil-beam DT neutron source, angle-correlated two neutrons emitted through (n,2n) reaction have directly been measured to determine (n,2n) reaction cross section with the coincidence detection technique for beryllium which is the most important element in the fusion reactor. In the experiment, two NE213 detectors were arranged very close to the sample to efficiently measure the two neutrons. The measured spectra were unfolded by FORIST with the detector response matrix evaluated by SCINFUL. As a relust, comparing with the evaluations of ENDF/B-VI and JENDL-3.3 for energies above 800 keV of the lower measurable limit energy, the shape of derived angula-differential cross-section fits JENDL-3.3 better than ENDF/B-VI. However, agreement of the cross section of (n,2n) above 800 keV was acceptable within 10 percents for both libraries.

Journal Articles

Measurement and analysis of neutron-induced alpha particle emission double-differential cross section of carbon at 14.2 MeV

Kondo, Keitaro; Murata, Isao*; Ochiai, Kentaro; Kubota, Naoyoshi*; Miyamaru, Hiroyuki*; Konno, Chikara; Nishitani, Takeo

Journal of Nuclear Science and Technology, 45(2), p.103 - 115, 2008/02

 Times Cited Count:7 Percentile:47.6(Nuclear Science & Technology)

We carried out a detailed measurement of neutron induced $$alpha$$-particle emission double-differential cross-section of carbon at 14.2 MeV, for which there were few measured data in spite of its importance in many applications. The obtained cross-section for the $$^{12}$$C(n,$$alpha_{0}$$)$$^{9}$$Be$$_{(ground state)}$$ reaction agreed well with previous experiments and evaluated nuclear data. The obtained angular-differential cross-section of the $$^{12}$$C(n,n'+3$$alpha$$) reaction for $$alpha$$-particles showed a strong forward-peaked distribution that suggested significant contribution of the direct reaction process to the 3$$alpha$$ breakup. We attempted to calculate the emitted particle spectra by means of a Monte Carlo method and estimate the branching ratio of the channels which contribute to the $$^{12}$$C(n,n'+3$$alpha$$) reaction. As a result, it was found that the $$^{12}$$C(n,$$alpha$$)$$^{9}$$Be* channels play an important role in generating the experimental double-differential cross-section both of emitted $$alpha$$-particles and neutrons. The estimated ratio of the $$^{12}$$C(n,$$alpha$$)$$^{9}$$Be* channels was around 40%, somewhat larger than those evaluated in previous studies.

Journal Articles

Verification of nuclear data for DT neutron induced charged-particle emission reaction of light nuclei

Kondo, Keitaro; Murata, Isao*; Ochiai, Kentaro; Kubota, Naoyoshi; Miyamaru, Hiroyuki*; Takagi, Satoshi*; Shido, Shoichi*; Konno, Chikara; Nishitani, Takeo

Fusion Engineering and Design, 82(15-24), p.2786 - 2793, 2007/10

 Times Cited Count:2 Percentile:78.37(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Charged-particle spectrometry using a pencil-beam DT neutron source for double-differential cross-section measurement

Kondo, Keitaro; Murata, Isao*; Ochiai, Kentaro; Miyamaru, Hiroyuki*; Kubota, Naoyoshi; Takagi, Satoshi*; Shido, Shoichi*; Takahashi, Akito*; Nishitani, Takeo

Nuclear Instruments and Methods in Physics Research A, 568(2), p.723 - 733, 2006/12

 Times Cited Count:14 Percentile:25.29(Instruments & Instrumentation)

Deuteron-tritium (DT) neutron induced charged-particle emission double-differential cross section (DDXc) is quite important to estimate nuclear heating, material damages for a fusion reactor. In order to realize the accurate measurement of the DDXc data especially for light nuclei, we propose a unique spectrometer system and a data processing method in this paper. The spectrometer overcomes the fundamental difficulty of the DDXc measurement with a pencil-beam neutron source and a counter telescope consisting of silicon surface barrier detectors. A superior S/N ratio, fine energy and angular resolutions, a wide detection energy range, and a excellent particle discrimination are realized. In order to confirm the validity of the spectrometer, measurements of the emitted $$alpha$$-particle from $$^{27}$$Al(${it n,x$alpha$}$) reaction and the recoiled proton from $$^{1}$$H(${it n,n}$) reaction are carried out. Based on the results, we conclude the validity and the superiority of the present spectrometry technique.

JAEA Reports

Development of measurement technique for charged-particle emission double-differential cross section using pencil-beam neutron source (Cooperative research)

Kondo, Keitaro; Ochiai, Kentaro; Kubota, Naoyoshi; Nishitani, Takeo; Murata, Isao*; Miyamaru, Hiroyuki*; Takahashi, Akito*

JAEA-Research 2006-016, 50 Pages, 2006/03

JAEA-Research-2006-016.pdf:6.25MB

Charged-particle emission double- differential cross section (DDXc) is quite important to estimate nuclear heating, material damages of a fusion reactor. We have developed a new technique for detailed measurement of DDXc. The technique overcomes fundamental difficulties of DDXc measurement with a pencil-beam neutron source and a counter telescope consisting of silicon surface barrier detectors. A superior S/N ratio, fine energy and angular resolutions, a wide detection energy range, and an excellent particle discrimination are realized together with a reasonable measurement time. In order to confirm the validity of the spectrometer, measurements of the emitted $$alpha$$-particle from $$^{27}$$Al(n,x$$alpha$$) reaction and the recoiled proton from $$^{1}$$H(n,n) reaction are carried out. Based on the results, we conclude the validity and the superiority of the present spectrometry technique.

Journal Articles

New approach to measure double-differential charged-particle emission cross sections of several materials for a fusion reactor

Kondo, Keitaro; Takagi, Satoshi*; Murata, Isao*; Miyamaru, Hiroyuki*; Takahashi, Akito*; Kubota, Naoyoshi; Ochiai, Kentaro; Nishitani, Takeo

Fusion Engineering and Design, 81(8-14), p.1527 - 1533, 2006/02

 Times Cited Count:12 Percentile:29.89(Nuclear Science & Technology)

In a fusion reactor development, double-differential charged-particle emission cross sections(DDXc) are necessary to estimate nuclear heating and material damages of candidate materials irradiated with neutrons. Especially in light nuclei such as Be, Li, and C, nuclear reactions are complicated and difficult to estimate energy spectra of emitted particles based only on theoretical calculations Therefore development of a new technique for precise measurements of DDXc is quite important. Recently we successfully developed a new spectrometer for measurement of DDXc using a pencil-beam DT neutron source of FNS in JAERI. In the present study we carried out measurements of DDXc of $$^{9}$$Be, $$^{12}$$C, $$^{19}$$F, and $$^{27}$$Al using the spectrometer. The present technique was valid from the result of measurement for the $$^{27}$$Al(n,x$$alpha$$) reactions. Slight differences appeared between measured data and evaluation or previous experimental values for $$^{9}$$Be(n,x$$alpha$$) reactions at backward scattering angle and in lower energy region.

Journal Articles

Measurement of energetic charged particles produced in fusion materials with 14 MeV neutron irradiation

Ochiai, Kentaro; Kondo, Keitaro; Murata, Isao*; Miyamaru, Hiroyuki*; Kubota, Naoyoshi; Takahashi, Akito*; Nishitani, Takeo

Fusion Engineering and Design, 75-79, p.859 - 863, 2005/11

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

The Fusion Neutronics Source (FNS) of JAERI currently carries out the measurements of energetic charged particles emitted from fusion materials irradiated with a well-collimated 14 MeV neutron beam. At the beginning, the double differential cross section beryllium was measured. We have measured proton, triton and a particle emitted from a beryllium sample of 100 $$mu$$m in thickness.The a particle and triton were produced by $$^{9}$$Be(n,$$alpha$$)$$^{6}$$He, $$^{9}$$Be(n,2n)2$$alpha$$ and $$^{9}$$Be(n,t)$$^{7}$$Li reactions respectively. Measured total reaction rates from the counts of a particles and tritons were 2.7$$times$$10$$^{-24}$$ and 6$$times$$10$$^{-27}$$/atom/neutron, respectively, which were consistent with the calculated values from the nuclear data JENDL-3.2.

Oral presentation

Nuclear reaction cross-section measurement for fusion reactor materials using pencil-beam DT neutron source

Kondo, Keitaro; Takagi, Satoshi*; Shiken, Kimiaki*; Shido, Shoichi*; Murata, Isao*; Miyamaru, Hiroyuki*; Ochiai, Kentaro; Kubota, Naoyoshi; Nishitani, Takeo

no journal, , 

no abstracts in English

Oral presentation

Measurement of Zr(n,2n) reaction cross section from the angle correlated neutron spectrum

Shiken, Kimiaki*; Takagi, Satoshi*; Kondo, Keitaro; Matsunaka, Masayuki*; Murata, Isao*; Miyamaru, Hiroyuki*; Ochiai, Kentaro; Nishitani, Takeo

no journal, , 

no abstracts in English

Oral presentation

Design of DT neutron spectrum shifter for integral benchmark experiment in the intermediate energy region

Ota, Masayuki*; Kondo, Keitaro*; Matsunaka, Masayuki*; Miyamaru, Hiroyuki*; Murata, Isao*; Ochiai, Kentaro; Konno, Chikara

no journal, , 

no abstracts in English

17 (Records 1-17 displayed on this page)
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