Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 35

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Nonresonant $$p$$-wave direct capture and interference effect observed in the $$^{16}$$O$$(n,gamma)^{17}$$O reaction

Nagai, Yasuki*; Kinoshita, Mitsutaka*; Igashira, Masayuki*; Nobuhara, Yuriko*; Makii, Hiroyuki; Mishima, Kenji*; Shima, Tatsushi*; Mengoni, A.*

Physical Review C, 102(4), p.044616_1 - 044616_8, 2020/10

 Times Cited Count:0 Percentile:0.02(Physics, Nuclear)

Journal Articles

Measurement of neutron scattering cross section of nano-diamond with particle diameter of approximately 5 nm in energy range of 0.2 meV to 100 meV

Teshigawara, Makoto; Tsuchikawa, Yusuke*; Ichikawa, Go*; Takata, Shinichi; Mishima, Kenji*; Harada, Masahide; Oi, Motoki; Kawamura, Yukihiko*; Kai, Tetsuya; Kawamura, Seiko; et al.

Nuclear Instruments and Methods in Physics Research A, 929, p.113 - 120, 2019/06

 Times Cited Count:7 Percentile:75.46(Instruments & Instrumentation)

A nano-diamond is an attractive neutron reflection material below cold neutron energy. The total neutron cross section of a nano-diamond was derived from a neutron transmission measurement over the neutron energy range of 0.2 meV to 100 meV because total neutron cross section data were not available. The total cross section of a nano-diamond with particle size of approximately 5 nm increased with a decrease in neutron energy to 0.2 meV. It was approximately two orders of magnitude larger than that of graphite at 0.2 meV. The contribution of inelastic scattering to the total cross section was to be shown negligible small at neutron energies of 1.2, 1.5, 1.9, 2.6, and 5.9 meV in the inelastic neutron scattering measurement. Moreover, small-angle neutron scattering measurements of the nano-diamond showed a large scattering cross section in the forward direction for low neutron energies.

Journal Articles

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

Journal Articles

$$E1$$ and $$E2$$ cross sections of the $$^{12}$$C($$alpha$$,$$gamma$$)$$^{16}$$O reaction at $$E_{rm{eff}}$$ $$sim$$ 1.2 MeV using pulsed $$alpha$$ beams

Makii, Hiroyuki; Ueda, Hitoshi*; Temma, Yasuyuki*; Nagai, Yasuki*; Shima, Tatsushi*; Fujimoto, Shinya*; Segawa, Mariko; Mishima, Kenji*; Nishiyama, Jun*; Igashira, Masayuki*

AIP Conference Proceedings 1269, p.283 - 288, 2010/10

 Times Cited Count:0 Percentile:0.02

The $$^{12}$$C($$alpha$$,$$gamma$$)$$^{16}$$O reaction cross section plays an important role in stellar evolution at the stage of helium-burning. However, the cross section at low energy still has a large uncertainty mainly due to the poor determination of the ratio of $$E2$$ cross section to $$E1$$ one. Hence, we have installed new system to make a precise measurement of the cross section. In this experiment, we used the high efficiency anti-Compton NaI(Tl) spectrometers with a large S/N ratio, an intense pulsed $$alpha$$ beams, and the monitoring system of target thickness. With use of the system we succeeded in removing a background due to neutron and could clearly detect the $$gamma$$-ray from the $$^{12}$$C($$alpha$$,$$gamma$$)$$^{16}$$O reaction with high statistics. We determined the $$E1$$ and $$E2$$ cross section down to $$E_{rm{eff}} sim $$ 1.2 MeV, and thus obtained results are compared to recent theoretical calculations.

Journal Articles

$$E1$$ and $$E2$$ cross sections of the $$^{12}$$C$$(alpha,gamma_{0})^{16}$$O reaction using pulsed $$alpha$$ beams

Makii, Hiroyuki; Nagai, Yasuki*; Shima, Tatsushi*; Segawa, Mariko; Mishima, Kenji*; Ueda, Hitoshi*; Igashira, Masayuki*; Osaki, Toshiro*

Physical Review C, 80(6), p.065802_1 - 065802_16, 2009/10

 Times Cited Count:30 Percentile:84.62(Physics, Nuclear)

We measured the $$gamma$$-ray angular distribution from $$^{12}$$C$$(alpha,gamma_{0})^{16}$$O to the ground state of $$^{16}$$O using a pulsed $$alpha$$ beam at $$E_{rm eff} = 1.6$$ and 1.4 MeV. True events of $$^{12}$$C$$(alpha,gamma_{0})^{16}$$O were discriminated from background events due to neutrons from $$^{13}$$C($$alpha,n$$)$$^{16}$$O with a time-of-flight method. The obtained $$gamma$$-ray spectrum with anti-Compton NaI(Tl) spectrometers showed a characteristic line shape from $$^{12}$$C$$(alpha,gamma_{0})^{16}$$O: the Doppler broadening and energy loss of $$alpha$$ particles in $$^{12}$$C targets. The astrophysical S factors for $$E1$$ and $$E2$$, $$S_{E1}(gamma_{0}:E_{rm eff})$$ and $$S_{E2}(gamma_{0}:E_{rm eff})$$, derived from the present cross sections are in excellent agreement with the values derived by $$R$$-matrix calculation of the $$beta$$-delayed $$alpha$$ spectrum of $$^{16}$$N, and by using the asymptotic normalization constant in the $$R$$-matrix fit.

Journal Articles

Design of neutron beamline for fundamental physics at J-PARC BL05

Mishima, Kenji*; Ino, Takashi*; Sakai, Kenji; Shinohara, Takenao; Hirota, Katsuya*; Ikeda, Kazuaki*; Sato, Hiromi*; Otake, Yoshie*; Omori, Hitoshi*; Muto, Suguru*; et al.

Nuclear Instruments and Methods in Physics Research A, 600, p.342 - 345, 2009/02

 Times Cited Count:24 Percentile:85.38(Instruments & Instrumentation)

A new beamline for a fundamental physics experiment is under construction at BL05 port in the Materials and Life Science Facility (MLF) at Japan Proton Accelerator Research Complex (J-PARC), this beamline is designed using novel techniques of neutron optics and it is termed "Neutron Optics and Physics". The beam from the moderator is deflected by multi-channel supermirrors and split into three branches for individual experiments. In this study, we have optimized the design of the beam optics and shields using the Monte Carlo simulation package PHITS. The neutron fluxes of beams are expected to be $$9.2 times 10^5/$$cm$$^2/mu$$str$$/$$s$$/$$MW, $$1.2 times 10^9/$$cm$$^2/$$s$$/$$MW, $$4.0 times 10^8/$$cm$$^2/$$s$$/$$MW, with polarization of 99.8%.

JAEA Reports

Performance-based improvement of the leakage rate test program for the reactor containment of HTTR; Adoption of revised test program containing "Type A, Type B and Type C tests"

Kondo, Masaaki; Kimishima, Satoru*; Emori, Koichi; Sekita, Kenji; Furusawa, Takayuki; Hayakawa, Masato; Kozawa, Takayuki; Aono, Tetsuya; Kuroha, Misao; Ouchi, Hiroshi

JAEA-Technology 2008-062, 46 Pages, 2008/10

JAEA-Technology-2008-062.pdf:11.62MB

The reactor containment of HTTR is tested to confirm leak-tight integrity of itself. "Type A test" has been conducted in accordance with the standard testing method in JEAC4203 since the preoperational verification of the containment was made. Type A tests are identified as basic one for measuring containment leakage rate, it costs much, however. Therefore, the test program for HTTR was revised to adopt an efficient and economical alternatives including "Type B and Type C tests". In JEAC4203-2004, following requirements are specified for adopting alternatives: upward trend of leakage rate by Type A test due to aging should not be recognized; criterion of combined leakage rate with Type B and Type C tests should be established; the criteria for Type A test and combined leakage rate test should be satisfied; correlation between the leakage rates by Type A test and combined leakage rate test should be recognized. Considering the performances of the tests, the policies of corresponding to the requirements were developed, which were accepted by the regulatory agency. This report presents an outline of the tests, identifies issues on the conventional test and summarizes the policies of corresponding to the requirements and of implementing the tests based on the revised program.

Journal Articles

$$E1$$ and $$E2$$ cross sections of the $$^{12}$$C($$alpha,gamma)^{16}$$O reaction at $$E_{cm} sim$$ 1.4 MeV using pulsed $$alpha$$ beams

Makii, Hiroyuki; Nagai, Yasuki; Mishima, Kenji*; Segawa, Mariko; Shima, Tatsushi*; Ueda, Hitoshi; Igashira, Masayuki*

AIP Conference Proceedings 1016, p.215 - 220, 2008/05

The $$^{12}$$C($$alpha,gamma)^{16}$$O reaction plays an important role in stellar evolution at the stage of helium-burning. However, the cross section at low energy still has a large uncertainty mainly due to the poor determination of the $$sigma_{E2}/sigma_{E1}$$ ratio. We have installed a new system to measure the $$gamma$$-ray angular distribution of the $$^{12}$$C($$alpha,gamma)^{16}$$O reaction to accurately determine the $$sigma_{E1}$$ and $$sigma_{E2}$$. In this experiment, we used high efficiency anti-Compton NaI(Tl) spectrometers to detect a $$gamma$$-ray from the reaction with a large S/N ratio, intense pulsed $$alpha$$ beams to discriminate true events from neutron induced background with a time-of-flight method, and the monitoring system of target thickness. We succeeded in removing a background due to neutrons and could clearly detect the $$gamma$$-ray from the $$^{12}$$C($$alpha,gamma)^{16}$$O reaction with high statics.

Journal Articles

Neutron-induced reactions using a $$gamma$$-ray detector in a $$^{12}$$C($$alpha,gamma$$)$$^{16}$$O reaction study

Makii, Hiroyuki; Nagai, Yasuki*; Mishima, Kenji*; Segawa, Mariko; Shima, Tatsushi*; Igashira, Masayuki*

Physical Review C, 76(2), p.022801_1 - 022801_5, 2007/08

 Times Cited Count:14 Percentile:69.56(Physics, Nuclear)

Neutron-induced background events occurring within a $$gamma$$-ray detector in the $$^{12}$$C($$alpha$$,$$gamma$$)$$^{16}$$O reaction study are discussed by comparing a spectrum taken by a NaI(Tl) detector with a pulsed $$alpha$$-beam with that taken previously by a Ge detector using a continuous $$alpha$$-beam. Both spectra contain such background events induced by neutrons from the $$({alpha},n)$$ reaction on $$^{13}$$C and/or $$^{9}$$Be contained in enriched $$^{12}$$C targets. These observations together with a calculated $$gamma$$-ray spectrum of the neutron-induced reaction by Ge isotopes indicate the thus-produced background events, which would be hardly reduced by using shield materials, become significant background in the $$^{12}$$C($$alpha$$,$$gamma$$)$$^{16}$$O reaction study at low $$alpha$$-beam energy.

Journal Articles

Neutron capture cross sections of $$^{186}$$Os, $$^{187}$$Os, and $$^{189}$$Os for the Re-Os chronology

Segawa, Mariko; Masaki, Tomohiro*; Nagai, Yasuki*; Temma, Yasuyuki*; Shima, Tatsushi*; Mishima, Kenji*; Igashira, Masayuki*; Goriely, S.*; Koning, A.*; Hilaire, S.*

Physical Review C, 76(2), p.022802_1 - 022802_5, 2007/08

 Times Cited Count:17 Percentile:74.31(Physics, Nuclear)

Discrete as well as continuum $$gamma$$-ray energy spectra from the neutron capture by $$^{186}$$Os, $$^{187}$$Os, and $$^{189}$$Os have been taken for the first time at 5 $$leq$$ En $$leq$$ 90 keV by an anti-Compton NaI(Tl) spectrometer. The detection of a weak discrete $$gamma$$-ray, about 0.5% of total $$gamma$$-ray strength, demonstrates the high sensitivity of the present measurement. The energy spectra enabled us to accurately determine the reaction cross sections with a small systematic uncertainty. Based on the new cross sections, we re-estimate on the basis of a careful reaction cross section calculation the correction factor F$$_{sigma}$$ for the neutron capture on the 9.75-keV first excited state in $$^{187}$$Os as a function of stellar temperature, as required to derive the age of the Galaxy within the Re-Os chronology.

Journal Articles

Highly polarized cold neutron beam obtained by using a quadrupole magnet

Oku, Takayuki; Yamada, Satoru; Shinohara, Takenao; Suzuki, Junichi; Mishima, Kenji*; Hirota, Katsuya*; Sato, Hiromi*; Shimizu, Hirohiko

Physica B; Condensed Matter, 397(1-2), p.188 - 191, 2007/07

 Times Cited Count:5 Percentile:28.6(Physics, Condensed Matter)

We have studied a neutron polarization method by means of a quadrupole magnet. By passing through the aperture of the quadrupole magnet (QM), positive and negative polarity neutrons are accelerated in opposite directions and spatially separated due to the magnetic field gradient. Then, by extracting one spin component, we can obtain a highly polarized neutron beam. Since polarized neutrons do not interact with any substances in this method, we can obtain the polarized neutron beam free from neutron attenuation. As a result of a cold neutron beam polarization experiment by using the QM, we obtained extremely high neutron polarization degree P0.999. In this paper, we show some experimental results of the neutron polarization experiment and discuss the application of the QM-based polarizing device to neutron scattering experiments.

JAEA Reports

Leakage rate test for reactor containment vessel of HTTR

Kondo, Masaaki; Sekita, Kenji; Emori, Koichi; Sakaba, Nariaki; Kimishima, Satoru; Kuroha, Misao; Noji, Kiyoshi; Aono, Tetsuya; Hayakawa, Masato

JAEA-Testing 2006-002, 55 Pages, 2006/07

JAEA-Testing-2006-002.pdf:6.36MB

The leakage rate test for the reactor containment vessel of HTTR is conducted in accordance with the absolute pressure method provided in Japan Electric Association Code(JEAC4203). Although leakage test of a reactor containment vessel is, in general, performed in condition of reactor coolant pressure boundary to be opened in order to simulate an accident, the peculiar test method to HTTR which use the helium gas as reactor coolant has been established, in which the pressure boundary is closed to avoid the release of fission products into the environment of the reactor containment vessel. The system for measuring and calculating the data for evaluating the leakage rate for containment vessel of HTTR was developed followed by any modifications. Recently, the system has been improved for more accurate and reliable one with any useful functions including real time monitoring any conditions related to the test. In addition, the configuration of containment vessel boundary for the test and the calibration method for the detectors for measuring temperature in containment vessel have been modified by reflecting the revision of the Code mentioned above. This report describes the method, system configuration, and procedures for the leakage rate test for reactor containment vessel of HTTR.

JAEA Reports

Maintenance of helium sampling system in HTTR

Sekita, Kenji; Emori, Koichi; Kuroha, Misao; Kimishima, Satoru; Wakabayashi, Hiroshi

JAEA-Testing 2006-001, 49 Pages, 2006/06

JAEA-Testing-2006-001.pdf:6.24MB

no abstracts in English

JAEA Reports

Report of investigation on malfunction of reserved shutdown system in HTTR

Hamamoto, Shimpei; Iigaki, Kazuhiko; Shimizu, Atsushi; Sawahata, Hiroaki; Kondo, Makoto; Oyama, Sunao; Kawano, Shuichi; Kobayashi, Shoichi; Kawamoto, Taiki; Suzuki, Hisashi; et al.

JAEA-Technology 2006-030, 58 Pages, 2006/03

JAEA-Technology-2006-030.pdf:10.69MB

During normal operation of High Temperature engineering Test Reactor (HTTR) in Japan Atomic Energy Agency (JAEA), the reactivity is controlled by the Control Rods (CRs) system which consists of 32 CRs (16 pairs) and 16 Control Rod Drive Mechanisms (CRDMs). The CR system is located in stand-pipes accompanied by the Reserved Shutdown System (RSS). In the unlikely event that the CRs fail to be inserted, the RSS is provided to insert B$$_{4}$$C/C pellets into the core. The RSS shall be designed so that the reactor should be held subcriticality from any operation condition by dropping in the pellets. The RSS consists of B$$_{4}$$C/C pellets, hoppers which contain the pellets, electric plug, driving mechanisms, guide tubes and so on. In accidents when the CRs cannot be inserted, an electric plug is pulled out by a motor and the absorber pellets fall into the core by gravity. A trouble, malfunction of one RSS out of sixteen, occurred during a series of the pre-start up checks of HTTR on February 21, 2005. We investigated the cause of the RSS trouble and took countermeasures to prevent the issue. As the result of investigation, the cause of the trouble was attributed to the following reason: In the motor inside, The Oil of grease of the multiplying gear flowed down from a gap of the oil seal which has been deformed and was mixed with abrasion powder of brake disk. Therefore the adhesive mixture prevented a motor from rotating.

Journal Articles

Development of vertical component isolation system with coned disk springs for FBR plant

Kitamura, Seiji; Okamura, Shigeki; Takahashi, Kenji; Kamishima, Yoshio*; Somaki, Takahiro*; Morishita, Masaki

Proceedings of 9th World Seminar on Seismic Isolation, Energy Dissipation and Active Vibration Control of Structures (CD-ROM), p.209 - 216, 2005/00

A structural concept of a vertical component isolation system for fast reactors, assuming a building adopting a horizontal base isolation system, has been studied. In this concept, a reactor vessel and major primary components are suspended from a large common deck supported by vertical isolation devices consisting of large coned disk springs. We designed the isolation device, which could be achieved vertical isolation frequency of 1 Hz and damping ratio of 20 %. Full scale coned disk spring and damper performance tests were carried out to verify the validity of design equations. And a series of shaking table test using a 1/8 scale model was performed. The test results fit well the simulation analysis results, so the validity of the design methods was able to be verified. The prospect that the vertical component isolation system applied to the FBR plant could technically realize was obtained.

Journal Articles

Study of survey and alignment for J-PARC

Mishima, Kenji*; Tani, Norio

Dai-14-Kai Kasokuki Kagaku Kenkyu Happyokai Hokokushu, 3 Pages, 2003/11

no abstracts in English

Journal Articles

R&D of a MW-class solid-target for spallation neutron source

Kawai, Masayoshi*; Furusaka, Michihiro*; Kikuchi, Kenji; Kurishita, Hiroaki*; Watanabe, Ryuzo*; Li, J.*; Sugimoto, Katsuhisa*; Yamamura, Tsutomu*; Hiraoka, Yutaka*; Abe, Katsunori*; et al.

Journal of Nuclear Materials, 318, p.35 - 55, 2003/05

R&D works for MW class solid target composed of tungsten to produce pulsed intense neutron source has been made in order to construct a future scattering facility. Three methods were investigated to prevent corrosion of tungsten from water; those are hipping, brazing and electric coating in molten salt bath. Hipping condition was optimized to be 1500 degree C in the previous work: here small punch test shows highest load for crack initiation of hipped materials at the boundary of W/Ta. The basic techniques for the other two methods were developed. Erosion test showed that uncovered W is susceptible of flowing water velocity. At high velocity w is easy to be eroded. For solid target design slab type and rod type targets were studied. As long as the optimized neutron performance is concerned, 1MW solid target is better than mercury target.

Journal Articles

High-frame rate neutron radioscopy with a steady thermal neutron beam

Mishima, Kaichiro*; Hibiki, Takashi*; Fujine, Shigenori*; Yoneda, Kenji*; Kanda, Keiji*; Nishihara, Hideaki*; Matsubayashi, Masahito; Tsuruno, Akira

Fifth World Conf. on Neutron Radiography, 0, p.140 - 147, 1996/00

no abstracts in English

Journal Articles

Coking determination in gas turbine engine nozzles using neutron radiography

J.T.Lindsay*; Fujine, Shigenori*; Mishima, Kaichiro*; Hibiki, Takashi*; Yoneda, Kenji*; *; Matsubayashi, Masahito; M.N.Islam*

Fifth World Conf. on Neutron Radiography, 0, p.571 - 577, 1996/00

no abstracts in English

Journal Articles

Visualization and measurements of two-phase flows in metallic ducts using neutrons as microscopic probes, 1; Time-resolved neutron radiography and its limited time-resolution

Mishima, Kaichiro*; Hibiki, Takashi*; Fujine, Shigenori*; Yoneda, Kenji*; Tsuruno, Akira; Matsubayashi, Masahito; Sobajima, Makoto

Nihon Kikai Gakkai Rombunshu, B, 61(591), p.161 - 168, 1995/11

no abstracts in English

35 (Records 1-20 displayed on this page)