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Journal Articles

Square and rhombic lattices of magnetic skyrmions in a centrosymmetric binary compound

Takagi, Rina*; Matsuyama, Naofumi*; Ukleev, V.*; Yu, L.*; White, J. S.*; Francoual, S.*; Mardegan, J. R. L.*; Hayami, Satoru*; Saito, Hiraku*; Kaneko, Koji; et al.

Nature Communications (Internet), 13(1), p.1472_1 - 1472_7, 2022/03

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

Measurements and analyses of the distribution of the radioactivity induced by the secondary neutrons produced by 17-MeV protons in compact cyclotron facility

Matsuda, Norihiro; Izumi, Yuichi*; Yamanaka, Yoshiyuki*; Gando, Toshiyuki*; Yamada, Masaaki*; Oishi, Koji*

EPJ Web of Conferences, 153, p.07001_1 - 07001_6, 2017/09

 Times Cited Count:0 Percentile:0.03

Journal Articles

Activation detector measurements at the hadron absorber of the NuMI neutrino beamline at Fermilab

Matsuda, Norihiro; Kasugai, Yoshimi; Matsumura, Hiroshi*; Iwase, Hiroshi*; Toyoda, Akihiro*; Yashima, Hiroshi*; Sekimoto, Shun*; Oishi, Koji*; Sakamoto, Yukio*; Nakashima, Hiroshi; et al.

Progress in Nuclear Science and Technology (Internet), 4, p.337 - 340, 2014/04

The Neutrinos at the Main Injector (NuMI) at Fermilab produces intense neutrino beam to investigate the phenomena of the neutrino mixing and oscillation. The Hadron Absorber, consists of thick blocks of aluminum, iron and concrete, is placed at the end of decay volume as a dump for primary proton and secondary particles generated in NuMI. In order to estimate the shielding effect, the reaction rate measurements with activation detector were carried out on the back surface of the absorber. The induced activities in the detectors were measured by analyzing their $$gamma$$-ray spectra using HPGe detectors. Two kind of peak was showed on two-dimensional distributions of obtained reaction rates at right angle to the beam direction. One was strong peaks at the both horizontal side. And, another smaller was at the top. It was concluded that these peaks were the results of particles streaming through the gaps in the Hadron Absorber shielding.

Journal Articles

Fitting method for spectrum deduction in high-energy neutron field induced by GeV-protons using experimental reaction-rate data

Kasugai, Yoshimi; Matsuda, Norihiro; Sakamoto, Yukio; Nakashima, Hiroshi; Yashima, Hiroshi*; Matsumura, Hiroshi*; Iwase, Hiroshi*; Hirayama, Hideo*; Mokhov, N.*; Leveling, A.*; et al.

Reactor Dosimetry; 14th International Symposium (ASTM STP 1550), p.675 - 689, 2012/08

Under the collaborative study project of JASMIN, shielding experiments has been carried out using the anti-proton target station (Pbar) of Fermilab. In the experiment, the multi-foil activation technique was utilized, and the neutron spectra in high-energy region between 1 and 100 MeV were deduced by using the "fitting method", which is newly developed. In this method, we made an assumption that neutron energy spectra could be expressed with a simple function. The validity of the fitting method was confirmed by comparison with the results of the unfolding method and the theoretical calculations. Finally, it was found that there are simple correlations between reaction rates and the adjusting parameters in the fitting function. The correlations are useful for estimating the adjusting parameters easily, and a neutron spectrum in the high-energy region can be deduced from a set of reaction-rate data without the complicated calculations of unfolding.

Journal Articles

Shielding experiments under JASMIN collaboration at Fermilab, 4; Measurement and analyses of high-energy neutron spectra in the anti-proton target station

Matsuda, Norihiro; Kasugai, Yoshimi; Sakamoto, Yukio; Nakashima, Hiroshi; Matsumura, Hiroshi*; Iwase, Hiroshi*; Kinoshita, Norikazu*; Hirayama, Hideo*; Yashima, Hiroshi*; Mokhov, N.*; et al.

Journal of the Korean Physical Society, 59(2), p.2055 - 2058, 2011/08

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

It is important to obtain neutron spectra and its intensity on shielding experiment. Deduction of high-energy neutron spectra were done using fitting and unfolding methods based on the shielding data obtained at the anti-proton (pbar) target station in Fermilab. The neutron spectra for fitting method is useful to be easily obtained and the values gave reasonable results compared with nuclear data. Therefore, that for unfolding methods included inconsistency. Furthermore, the deduced neutron spectra were verified through the calculation analyses by PHITS code.

Journal Articles

Shielding experiments by the JASMIN collaboration at Fermilab, 2; Radioactivity measurement induced by secondary particles from the anti-proton production target

Yashima, Hiroshi*; Matsuda, Norihiro; Kasugai, Yoshimi; Nakashima, Hiroshi; Sakamoto, Yukio; Matsumura, Hiroshi*; Iwase, Hiroshi*; Kinoshita, Norikazu*; Boehnlein, D.*; Lautenschlager, G.*; et al.

Journal of the Korean Physical Society, 59(2), p.2051 - 2054, 2011/08

 Times Cited Count:1 Percentile:12.07(Physics, Multidisciplinary)

The experiment was performed at the anti-proton (pbar) production target station in Fermi National Accelerator Laboratory. At the pbar target station, an anti-proton production target, consisted of Inconel and copper disks, were irradiated by 120 GeV proton beam. The beam intensity was 2.0 $$times$$ 10$$^{12}$$ proton per second. Al, Nb, Cu, Au samples were set around the target to investigate the spatial and energy distribution of secondary particles emitted from the target. After irradiation, induced activities of samples were measured by using HPGe detector. The reaction rates of 30 nuclides induced in Al, Nb, Cu, Au samples were obtained. The reaction rates of these nuclides increase for samples placed on forward angle position. The angle dependence of these reaction rates becomes larger for increasing threshold energy. These experimental results compared with the calculation. The calculated results generally agree with the experimental results within a factor of 3.

Journal Articles

Shielding experiments under JASMIN collaboration at Fermilab, 3; Measurement of high-energy neutrons penetrating a thick iron shield from the antiproton production target by Au activation method

Matsumura, Hiroshi*; Kinoshita, Norikazu*; Iwase, Hiroshi*; Toyoda, Akihiro*; Kasugai, Yoshimi; Matsuda, Norihiro; Sakamoto, Yukio; Nakashima, Hiroshi; Yashima, Hiroshi*; Mokhov, N.*; et al.

Journal of the Korean Physical Society, 59(2), p.2059 - 2062, 2011/08

 Times Cited Count:1 Percentile:12.07(Physics, Multidisciplinary)

In an antiproton production (Pbar) target station of the Fermi National Accelerator Laboratory (FNAL), the secondary particles produced by bombarding a target with 120-GeV protons are shielded by a thick iron shield. In order to obtain experimental data on high-energy proton accelerator facilities, we indirectly measured $$>$$ 100-MeV neutrons at the outside of the iron shield. The measurement was performed by using the Au activation method coupled with a low-background $$gamma$$-ray counting system. As an indicator for the neutron flux, we determined the production rates of 8 spallation nuclides ($$^{196}$$Au, $$^{188}$$Pt, $$^{189}$$Ir, $$^{185}$$Os, $$^{175}$$Hf, $$^{173}$$Lu, $$^{171}$$Lu, and $$^{169}$$Yb) in the Au activation detector. The measured production rates were compared with the theoretical production rates calculated using PHITS. We proved that the Au activation method can serve as a powerful tool for indirect measurements of $$>$$ 100-MeV neutrons that play a vital role in neutron transport.

Journal Articles

Thermoelectric response in the incoherent transport region near Mott transition; The Case study of La$$_{1-x}$$Sr$$_x$$VO$$_3$$

Uchida, Masaki*; Oishi, Koji*; Matsuo, Mari; Koshibae, Wataru*; Onose, Yoshinori*; Mori, Michiyasu; Fujioka, Jun*; Miyasaka, Shigeki*; Maekawa, Sadamichi; Tokura, Yoshinori*

Physical Review B, 83(16), p.165127_1 - 165127_5, 2011/04

 Times Cited Count:25 Percentile:73.08(Materials Science, Multidisciplinary)

Journal Articles

Shielding experiments at high energy accelerators of Fermilab, 2; Spatial distribution measurement of reaction rate behind the shield and its application for Moyer model

Yashima, Hiroshi*; Kasugai, Yoshimi; Matsuda, Norihiro; Matsumura, Hiroshi*; Iwase, Hiroshi*; Kinoshita, Norikazu*; Mokhov, N.*; Leveling, A.*; Boehnlein, D.*; Vaziri, K.*; et al.

Progress in Nuclear Science and Technology (Internet), 1, p.48 - 51, 2011/02

The shielding experiment was performed at the anti-proton production target station in Fermi National Accelerator Laboratory. Aluminum, Bismath, Niobium, Copper and Indium samples were placed behind the shields. After irradiation, induced activities of samples were measured by using HPGe detector. The spatial distribution of reaction rate of samples which were placed behind the iron and concrete shields were obtained. The measured data shows that the reaction rates on the outer surfaces of the iron and concrete shields increases toward the downstream of the target. The obtained reaction rates were also fitted to Moyer's formula, and the attenuation lengths for iron and concrete shields were obtained.

Journal Articles

Shielding experiments at high energy accelerators of Fermilab, 3; Neutron spectrum measurements in intense pulsed neutron fields of the 120-GeV proton facility using a current Bonner sphere technique

Hagiwara, Masayuki*; Sanami, Toshiya*; Iwamoto, Yosuke; Arakawa, Hiroyuki*; Shigyo, Nobuhiro*; Mokhov, N.*; Leveling, A.*; Boehnlein, D.*; Vaziri, K.*; Nakamura, Takashi*; et al.

Progress in Nuclear Science and Technology (Internet), 1, p.52 - 56, 2011/02

In pbar target station, the pulsed proton beam with the power of around 75 kW and the time structure of 1.6 $$mu$$s pulse width and 2.2 s cycle time bombards the pbar production target and produces high instantaneous intensity neutron (burst neutron) fields. The duration of the burst neutrons, which is less than $$mu$$s, is very severe condition to measure neutron spectra with a conventional Bonner sphere technique with pulse readout electronics because of signal pile-up problem. In this study, we have developed a current readout Bonner sphere technique to measure neutron spectra in a burst neutron field. We have measured the neutron spectra on the pbar target and graphite dump. The neutron spectra obtained with the present technique show generally good agreements with the calculation results using MARS code except difference of the thermal neutron flux due to the geometrical problem.

Journal Articles

Shielding experiments at high energy accelerators of Fermilab, 4; Calculation analyses

Matsuda, Norihiro; Kasugai, Yoshimi; Matsumura, Hiroshi*; Yashima, Hiroshi*; Iwase, Hiroshi*; Kinoshita, Norikazu*; Sanami, Toshiya*; Mokhov, N.*; Leveling, A.*; Boehnlein, D.*; et al.

Progress in Nuclear Science and Technology (Internet), 1, p.57 - 60, 2011/02

The anti-proton (pbar) production target in Fermi National Accelerator Laboratory can be produced a wide variety of secondary particles including of anti-protons, by bombarding with protons accelerated to 120 GeV. The shielding experimental data, which was obtained around the pbar target, make possible to validate the accuracies of the general-purpose Monte Carlo simulation codes. In this paper, spatial distribution of reaction rates were calculated with two-dimensional (r-z) geometry simplified the real pbar target station using the PHITS, MARS and MCNPX code. These experimental data in iron shield were compared with the calculated data. The comparison for attenuation length of iron were good agreement between the experiments and calculations.

Journal Articles

Thick target neutron yield at 0 degree by 250 and 350 MeV protons

Iwamoto, Yosuke; Taniguchi, Shingo*; Nakao, Noriaki*; Itoga, Toshio*; Nakamura, Takashi*; Nakane, Yoshihiro; Nakashima, Hiroshi; Satoh, Daiki; Yashima, Hiroshi*; Yamakawa, Hiroshi*; et al.

Proceedings of 8th Specialists' Meeting on Shielding Aspects of Accelerators, Targets and Irradiation Facilities (SATIF-8), p.195 - 203, 2010/03

Neutron energy spectra at 0 degree produced from stopping-length thick graphite, aluminum, iron and lead targets bombarded by 250 MeV and 350 MeV protons were measured at the neutron TOF course at RCNP of Osaka University. The neutron energy spectra were obtained by using the time-of-flight technique in the energy range from 10 MeV to incident proton energy. To compare the experimental results, Monte Carlo calculations by the PHITS and MCNPX codes using the JENDL-HE and the LA150 evaluated nuclear data files were performed. It was found that these calculated results at 0-degree generally underestimated the experimental results for all targets in the energy range above 20 MeV.

Journal Articles

Experimental studies of shielding and irradiation effects at high energy accelerator facilities

Nakashima, Hiroshi; Sakamoto, Yukio; Iwamoto, Yosuke; Matsuda, Norihiro; Kasugai, Yoshimi; Nakane, Yoshihiro; Masukawa, Fumihiro; Mokhov, N.*; Leveling, A.*; Boehnlein, D.*; et al.

Nuclear Technology, 168(2), p.482 - 486, 2009/11

BB2007-3640.pdf:0.22MB

 Times Cited Count:7 Percentile:48.67(Nuclear Science & Technology)

Experimental studies of shielding and radiation effects have been started using 120-GeV proton synchrotron at Fermi National Accelerator Laboratory (FNAL) under collaboration between FNAL and Japan. The first campaign of the experiment was carried out at the Pbar target station and Numi experimental station at FNAL, using antiproton and neutrino production targets irradiated by 120-GeV protons. The generated secondary particles passing through steel, concrete and rock were measured by activation methods as well as by other detectors such as scintillator with a veto counter, phoswich detector and a Bonner ball counter on trial. Preliminary experimental results are presented.

Journal Articles

Measurement of thick target neutron yields at 0$$^{circ}$$ bombarded with 140, 250 and 350 MeV protons

Iwamoto, Yosuke; Taniguchi, Shingo*; Nakao, Noriaki*; Itoga, Toshio*; Yashima, Hiroshi*; Nakamura, Takashi*; Satoh, Daiki; Nakane, Yoshihiro; Nakashima, Hiroshi; Kirihara, Yoichi*; et al.

Nuclear Instruments and Methods in Physics Research A, 593(3), p.298 - 306, 2008/08

 Times Cited Count:10 Percentile:59.39(Instruments & Instrumentation)

Neutron energy spectra at 0$$^{circ}$$ produced from stopping-length graphite, aluminum, iron and lead targets bombarded with 140, 250 and 350 MeV protons were measured at the neutron TOF course in RCNP of Osaka University. The neutron energy spectra were obtained by using the time-of-flight technique in the energy range from 10 MeV to incident proton energy. To compare the experimental results, Monte Carlo calculations with the PHITS and MCNPX codes were performed using the JENDL-HE and the LA150 evaluated nuclear data files, the ISOBAR model implemented in PHITS, and the LAHET code in MCNPX. It was found that these calculated results at 0$$^{circ}$$ generally agreed with the experimental results in the energy range above 20 MeV except for graphite at 250 and 350 MeV.

Journal Articles

Measurement of neutron production spectra at the forward direction from thick graphite, aluminum, iron and lead targets bombarded by 250 MeV protons

Iwamoto, Yosuke; Taniguchi, Shingo*; Nakao, Noriaki*; Itoga, Toshio*; Nakamura, Takashi*; Nakane, Yoshihiro; Nakashima, Hiroshi; Satoh, Daiki; Yashima, Hiroshi*; Yamakawa, Hiroshi*; et al.

JAEA-Conf 2006-009, p.118 - 123, 2006/11

Neutron energy spectra produced at the forward direction from thick graphite, aluminum, iron and lead targets bombarded by 250 MeV protons were measured by the TOF method at RCNP of Osaka University. The experimental data were compared with the calculated results of the PHITS, MCNPX codes. All calculations give lower neutron energy spectra than the experimental ones for all targets above 20 MeV and must be improved for neutron production at 0-degree. These experimental data will be useful as benchmark data for investigating the accuracy of the Monte Carlo simulation and for the shielding design of accelerator facilities.

Journal Articles

Measurement of neutron spectra produced in the forward direction from thick graphite, Al, Fe and Pb targets bombarded by 350 MeV protons

Iwamoto, Yosuke; Taniguchi, Shingo*; Nakao, Noriaki*; Itoga, Toshio*; Nakamura, Takashi*; Nakane, Yoshihiro; Nakashima, Hiroshi; Satoh, Daiki; Yashima, Hiroshi*; Yamakawa, Hiroshi*; et al.

Nuclear Instruments and Methods in Physics Research A, 562(2), p.789 - 792, 2006/06

 Times Cited Count:6 Percentile:45.27(Instruments & Instrumentation)

Neutron energy spectra produced from thick targets play an important role in validation of calculation codes that are employed in the design of spallation neutron sources and the shielding design of accelerator facilities. However, appropriate experimental data were scarce in the forward direction for the incident energy higher than 100 MeV. In this study, neutron spectra at 0 degree from thick targets bombarded with 350 MeV protons were measured by the time-of-flight technique using an NE213. The targets used were graphite, Al, Fe and Pb and their thicknesses were chosen to be a little thicker than the stopping lengths. The experiment was carried out at the TOF course of the RCNP (Research Center of Nuclear Physics) ring cyclotron, Osaka University. The flight path length between center of the target and of an NE213 were 11.4 m for the measurement of low energy neutrons and 95 m for high energy neutrons. The experimental data are compared with the calculated results by using the Monte Carlo transport codes, such as MCNPX and PHITS codes.

Journal Articles

Thermal analysis and Ohmic loss estimation of polarizer for ITER ECCD system

Saigusa, Mikio*; Takahashi, Koji; Kashiwa, Yoshinori*; Oishi, Shimpei*; Hoshi, Yuki*; Nakahata, Hiroyuki*; Kasugai, Atsushi; Sakamoto, Keishi; Imai, Tsuyoshi*

Fusion Engineering and Design, 74(1-4), p.473 - 478, 2005/11

 Times Cited Count:4 Percentile:25.79(Nuclear Science & Technology)

The specification of an electron cyclotron current driving (ECCD) system in International Thermonuclear Experimental Reactor (ITER) demands severe operational conditions for transmission lines and polarizers. For evaluating Ohmic loss of a miter bend type polarizer, the six polarizers were made of chromium copper alloy, installed in miter bends and tested at a frequency of 170GHz, rf power of 441kW and pulse duration of 0.1-6 seconds. The increase in temperature on the back of the grooved mirrors has been measured with thermo couplers during high power rf pulses. The Ohmic loss of grooved mirrors strongly depends on the rotation angle of the polarization plane of the incident waves and the mirror rotation in high power experiments, for example the Ohmic loss distributed from 0.2% to1.6%. The thermal analysis of grooved mirror has been performed with the 3D FEM code: FEVA. The all strange behavior of Ohmic loss of polarizers could be explained, theoretically.

Journal Articles

Study of ohmic loss of high power polarizers at 170 GHz for ITER

Kashiwa, Yoshinori*; Saigusa, Mikio*; Takahashi, Koji; Oishi, Shimpei*; Hoshi, Yuki*; Kasugai, Atsushi; Sakamoto, Keishi; Imai, Tsuyoshi

Proceedings of 2004 International Symposium on Microwave Science and Its Application to Related Fields (Microwave 2004), p.527 - 530, 2004/07

An electron cyclotron current drive (ECCD) system is, especially, necessary to suppress the neoclassical tearing mode instability in ITER. The polarizers are one of the important components in the ECCD system, to generate optimum polarization for an efficient ECCD. An ohmic loss of the polarizers is evaluated, when 170GHz, high power RF wave taransmits, in oreder to investigate its performance. The maximum temperature increase on the back plate of the deep grooved and the conventinal type were 65$$^{circ}$$C and 30$$^{circ}$$C, respectively. RF power and pulse were 441kW and 6sec, respectively. The dependence of temperature increase on the plolarizer angle obtained in the experiment agrees with the calculation, qualitatively. It was also found that the significant reduction of ohmic loss on the polarizers was achievable with the optimized rotation angle of the linearly polarized incident wave.

Journal Articles

Study of Joule loss of grooved mirror polarizers

Saigusa, Mikio*; Takahashi, Koji; Oishi, Shimpei*; Kashiwa, Yoshitada*; Hoshi, Yuki*; Kobayashi, Yuki*; Kasugai, Atsushi; Sakamoto, Keishi; Imai, Tsuyoshi

Proceedings of IAEA TM on ECRH Physics and Technology for ITER (CD-ROM), 7 Pages, 2003/00

The specified elliptical polarization which is necessary to excite a pure ordinary or extraordinary mode, when rf waves obliquely propagate in plasma, for electron cyclotron current drive(ECCD) can be produced by a grooved mirror polarizer. The Joule loss of deeped groove mirrors has been experimentally investigated at a frequency of 170 GHz. The strange dependence of the Joule loss of groove mirror on the mirror rotation angle was obtained. In addition, maximum loss of 0.8% in regard to the injection rf power to the mirrors was estimated. The calculation code to estimate the Joule loss of grooved mirror is developed for the structure analysis. The dependence of the mirror on its rotation angle can be explained by the calculation results, clearly.

32 (Records 1-20 displayed on this page)