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Hiroshi Matsumura,Norikazu Kinoshita,Hiroshi Iwase,Akihiro Toyoda,Yoshimi Kasugai,Norihiro Matsuda,Yukio Sakamoto,Hiroshi Nakashima,Hiroshi Yashima,Nikolai Mokhov,Anthony Leveling,David Boehnlein,Kamr 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
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 neutron transport at more than 100-GeV-proton accelerator facilities, we indirectly measured more than 100-MeV neutrons at the outside of the iron shield at an angle of 50˚ in the Pbar target station. The measurement was performed by using the Au activation method coupled with a low-background γ-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 more than100-MeV neutrons that play a vital role in neutron transport. These results will be important for clarifying the problems in theoretical calculations of high-energy neutron transport.
Hiroshi Yashima,Norihiro Matsuda,Yoshimi Kasugai,Hiroshi Nakashima,Yukio Sakamoto,Hiroshi Matsumura,Hiroshi Iwase,Norikazu Kinoshita,David Boehnlein,Gary Lautenschlager,Anthony Leveling,Nikolai Mokhov 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The JASMIN Collaboration has performed an experiment to conduct measurements of nuclear reaction rates around the anti-proton production (Pbar) target at the Fermi National Accelerator Laboratory (FNAL). At the Pbar target station, the target, consisting an Inconel 600 cylinder, was irradiated by a 120 GeV/c proton beam from the FNAL Main Injector. The beam intensity was 3.6 X 10^(12) protons per second. Samples of Al, Nb, Cu, and Au were placed near the target to investigate the spatial and energy distribution of secondary particles emitted from it. After irradiation, the induced activities of the samples were measured by studying their gamma ray spectra using HPGe detectors. The production rates of 30 nuclides induced in Al, Nb, Cu, Au samples were obtained. These rates increase for samples placed in a forward (small angle) position relative to the target. The angular dependence of these reaction rates becomes larger for increasing threshold energy. These experimental results are compared with Monte Carlo calculations. The calculated results generally agree with the experimental results to within a factor of 2 to 3.
Seiji Nakashima,Hironori Fujisawa,Masaru Shimizu,Osami Sakata,Tomoaki Yamada,Hiroshi Funakubo,박정민,Takeshi Kanashima,Masanori Okuyama 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.31
An electric-field-induced strain at 80 K in a 350-nm-thick BiFeO_3 (BFO) thin film deposited by pulsed laser deposition has been investigated by a time-resolved x-ray diffraction under an electric field using a synchrotron radiation. A 300-nsec-width and 804.09-nsec-period voltage pulses were applied to the BFO thin film during the measurements. The time-resolved-x-ray diffraction profile around BFO (001) diffraction peak indicates that BFO (001) diffraction peak shifts to lower angle side during the voltage application. A strain estimated from the peak shift lineally increases with increasing the amplitude of the voltage pulses. A piezoelectric constant (d_(33)) of (001)-oriented domains in the polycrystalline BFO thin film at 80 K is 20.2 pm/V. The value is smaller than that measured at RT of 27.8 pm/V in our previous report.
Maximum-Efficiency Tracking Scheme for Piezoelectric-Transformer Inverter with Dimming Control
Satoshi Nakashima,Hiroshi Ogasawara,Hidenori Kakehashi,Tamotsu Ninomiya 전력전자학회 2001 ICPE(ISPE)논문집 Vol.2001 No.10
This paper provides a solution for the problem of efficiency decrease caused by load variation. A novel control scheme of tracking the PT's operation frequency for the maximum efficiency is proposed. As a result, a high efficiency over 80% has been achieved even under the output-current decrease down to 10% of the full load current.
Characteristics of Radiation-Resistant Real-Time Neutron Monitor for Accelerator-Based BNCT
Nakamura, Takemi,Sakasai, Kaoru,Nakashima, Hiroshi,Takamiya, Koichi,Kumada, Hiroaki The Korean Association for Radiation Protection 2016 방사선방어학회지 Vol.41 No.2
Background: For an accelerator-based BNCT, we have fabricated a new detector consisting of quartz optical fibers that have excellent radiation-resistant characteristics. Materials and Methods: The developed detectors were irradiated at Kyoto University Research Reactor. Results and Discussion: The experimental results showed that the new detector had good output linearity for the neutron intensity, and the response of the new detector did not decrease during the irradiation. Conclusion: The new detector consisting of quartz optical fibers can be applied to measurement of neutron field of an accelerator-based BNCT.
Ryo Kishimoto,Masafumi Kobune,Hiroshi Nishioka,Takeyuki Kikuchi,Hajime Kishi,Hironori Fujisawa,Seiji Nakashima,Masaru Shimizu,Satoshi Kimura 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.7
<EM>a-</EM> and <I>b</I>-axis-oriented Bi<SUB>3.25</SUB>Nd<SUB>0.75</SUB>Ti<SUB>3</SUB>O<SUB>12</SUB> (BNT) nanoplates, 3.0 mm thick, were fabricated on conductive Nb:TiO<SUB>2</SUB>(101) substrates with 0.79 mass% Nb at 650C by high-temperature sputtering. Successively, the fabrication of inorganic-organic composites was carried out by introducing an epoxy resin to the spaces between BNT nanoplates. The fourier transform infrared spectroscopy (FT-IR) and energy dispersive X-ray (EDX) elemental mapping results confirmed that the fabricated composite was an inorganic-organic hybridized material which introduced the cured epoxy resin into the spaces between BNT nanoplates. Based on polarization reversal measurements of the fabricated BNT-epoxy resin composites by piezoresponse force microscopy (PFM), it is shown that the composites have potential as ferroelectric microelement materials.
( Indrawan Cahyo Adilaksono ),( Hiroshi Shimizu ),( Hiroshi Nakashima ),( Juro Miyasaka ),( Katsuaki Ohdoi ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1
Generation of Ultrafine Bubble (UFB) on hydroponic culture solution has been reported to be able for stimulating the growth of plant. However, the promoting effect of UFB is still hard and inconsistent to be obtained due to the unknown optimum generation of UFB. Generation time of UFB influenced UFB concentration on hydroponic solution. Furthermore, the concentration of UFB have positive correlation with oxidative stress on plant that might affect the growth of plant. In this study, we aim to investigate growth response of lettuce to different UFB water treatment so that the optimum generation of UFB can be obtained. Fifteen seedlings were cultivated on a tray for 4 weeks. The cultivation was conducted at air temperature 20-23°C, relative humidity 60%-80%, under white LEDs that were adjusted at 200 ± 10 μmol·m-2·s-1 and irradiation cycle was set at 16h/8h (light/dark). Ten lettuces were harvested (1st Harvest) on 14th day and five lettuces were harvested (2nd Harvest) on 28th day. Air ultrafine bubble water was generated by UFB Generator (FZ1N-10 I, IDEC Corporation, Japan). UFB water was generated with 3 different generation time; 12 minutes (Gt1), 30 minutes (Gt2), and 120 minutes (Gt3). Generation time of UFB water was parallel with pass number. Pass number is the number of times the control water circulated entirely through the UFB generator. In this experiment, pass number were respectively 10 pass number (Gt1), 25 pass number (Gt2), and 100 pass number (Gt3). Each UFB water (Gt1, Gt2, and Gt3) were distributed respectively into 5 trays with different mixtures between UFB water and normal water as UFB water treatment (10% UFB water, 30% UFB water, 50% UFB water, 75% UFB water, and 100% UFB water). In addition, a tray with normal water was prepared as control treatment. Hydroponic solution was maintained at similar condition of DO, EC, pH, and temperature. The final result reconfirmed again the ability of air UFB water to accelerate the growth of lettuce on hydroponic solution. However, the excess or lack of UFB concentration did not significantly influence the growth of lettuce compared to control treatment. Since, the excess concentration of UFB might inhibit the growth of lettuce due to oxidative stress inside the plant. Moreover, lack concentration of UFB is not enough to stimulate the growth of lettuce. On the other hand, appropriate concentration of UFB significantly increased the fresh weight and dry weight of lettuce. The optimum growth of lettuce tended to shift into low concentration of UFB water when the generation time of UFB water is increased. In our experiment, the optimum growth of lettuce was obtained on 30% UFB water (Gt3) treatment and 75% UFB water (Gt2) treatment. Thus, this result illustrates how different generation of UFB will lead into different final result due to the important role of UFB concentration on the hydroponic solution.