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Journal Articles

Kinetic inductance neutron detector operated at near critical temperature

Vu, TheDang; Nishimura, Kazuma*; Shishido, Hiroaki*; Harada, Masahide; Oikawa, Kenichi; Miyajima, Shigeyuki*; Hidaka, Mutsuo*; Oku, Takayuki; Soyama, Kazuhiko; Aizawa, Kazuya; et al.

Journal of Physics; Conference Series, 1590, p.012036_1 - 012036_9, 2020/07

Journal Articles

Temperature dependent characteristics of neutron signals from a current-biased Nb nanowire detector with $$^{10}$$B converter

Vu, TheDang; Iizawa, Yuki*; Nishimura, Kazuma*; Shishido, Hiroaki*; Kojima, Kenji*; Oikawa, Kenichi; Harada, Masahide; Miyajima, Shigeyuki*; Hidaka, Mutsuo*; Oku, Takayuki; et al.

Journal of Physics; Conference Series, 1293, p.012051_1 - 012051_9, 2019/10

Journal Articles

Study on loss-of-cooling and loss-of-coolant accidents in spent fuel pool, 1; Overview

Kaji, Yoshiyuki; Nemoto, Yoshiyuki; Nagatake, Taku; Yoshida, Hiroyuki; Tojo, Masayuki*; Goto, Daisuke*; Nishimura, Satoshi*; Suzuki, Hiroaki*; Yamato, Masaaki*; Watanabe, Satoshi*

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05

In this research program, cladding oxidation model in SFP accident condition, and numerical simulation method to evaluate capability of spray cooling system which was deployed for spent fuel cooling during SFP accident, have been developed. These were introduced into the severe accident codes such as MAAP and SAMPSON, and SFP accident analyses were conducted. Analyses using Computational Fluid Dynamics (CFD) code were conducted as well for the comparison with SA code analyses and investigation of detail in the SFP accident. In addition, three-dimensional criticality analysis method was developed as well, and safer loading pattern of spent fuels in pool was investigated.

Journal Articles

Ion acceleration via "nonlinear vacuum heating" by the laser pulse obliquely incident on a thin foil target

Yogo, Akifumi*; Bulanov, S. V.; Mori, Michiaki; Ogura, Koichi; Esirkepov, T. Z.; Pirozhkov, A. S.; Kanasaki, Masato*; Sakaki, Hironao; Fukuda, Yuji; Bolton, P.; et al.

Plasma Physics and Controlled Fusion, 58(2), p.025003_1 - 025003_7, 2016/02

 Times Cited Count:4 Percentile:65.53(Physics, Fluids & Plasmas)

Journal Articles

A Laser-plasma-produced soft X-ray laser at 89 eV generates DNA double-strand breaks in human cancer cells

Sato, Katsutoshi*; Nishikino, Masaharu; Kawachi, Tetsuya; Shimokawa, Takashi*; Imai, Takashi*; Teshima, Teruki*; Nishimura, Hiroaki*; Kando, Masaki

Journal of Radiation Research, 56(4), p.633 - 638, 2015/07

 Times Cited Count:1 Percentile:90.11(Biology)

While X-ray laser is expected to be widely applied to biomedical studies, this has not been achieved to date and its biological effects such as DNA damage have not been evaluated. As a first step for its biological application, we developed a culture cell irradiation system using laser-plasma soft X-ray laser and investigated whether the soft X-ray laser is able to induce the DNA double strand breaks (DSBs) in living cells or not. The human adenocarcimona cell line A549 was irradiated with the soft X-ray laser at a photon energy of 89 eV and then the repair focus formation of the DSBs was assessed by immunofluorescence staining with anti-phosphorylated DNA-PKcs antibody. As a result, the phosphorylated DNA-PKcs foci were clearly identified even with just a single shot of the soft X-ray laser. In this study, we successfully demonstrated for the first time that soft X-ray laser at 89 eV induced the DNA double strand breaks in living cells.

Journal Articles

Density and X-ray emission profile relationships in highly ionized high-Z laser-produced plasmas

Yoshida, Kensuke*; Fujioka, Shinsuke*; Higashiguchi, Takeshi*; Ugomori, Teruyuki*; Tanaka, Nozomi*; Kawasaki, Masato*; Suzuki, Yuhei*; Suzuki, Chihiro*; Tomita, Kentaro*; Hirose, Ryoichi*; et al.

Applied Physics Letters, 106(12), p.121109_1 - 121109_5, 2015/03

 Times Cited Count:6 Percentile:63.42(Physics, Applied)

Journal Articles

Conference report; The 16th International Workshop on Radiative Properties of Hot Dense Matter

Sasaki, Akira; Nishimura, Hiroaki*; Onishi, Naofumi*

Purazuma, Kaku Yugo Gakkai-Shi, 91(2), p.166 - 167, 2015/02

no abstracts in English

Journal Articles

Efficient extreme ultraviolet emission from one-dimensional spherical plasmas produced by multiple lasers

Yoshida, Kensuke*; Fujioka, Shinsuke*; Higashiguchi, Takeshi*; Ugomori, Teruyuki*; Tanaka, Nozomi*; Ohashi, Hayato*; Kawasaki, Masato*; Suzuki, Yuhei*; Suzuki, Chihiro*; Tomita, Kentaro*; et al.

Applied Physics Express, 7(8), p.086202_1 - 086202_4, 2014/08

 Times Cited Count:23 Percentile:22.76(Physics, Applied)

We demonstrate high conversion efficiency for extreme ultraviolet (EUV) emission at 6.5-6.7 nm from multiple laser beam-produced one-dimensional spherical plasmas. Multiply charged-state ions produce strong resonance emission lines, which combine to yield intense unresolved transition arrays in Gd, Tb, and Mo. The maximum in-band EUV conversion efficiency was observed to be 0.8%, which is one of the highest values ever reported due to the reduction of plasma expansion loss.

Journal Articles

Development of small specimen test techniques for the IFMIF test cell

Wakai, Eiichi; Kim, B. J.; Nozawa, Takashi; Kikuchi, Takayuki; Hirano, Michiko*; Kimura, Akihiko*; Kasada, Ryuta*; Yokomine, Takehiko*; Yoshida, Takahide*; Nogami, Shuhei*; et al.

Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 6 Pages, 2013/03

Journal Articles

Quantitative measurement of hard X-ray spectra for high intensity laser produced plasma

Zhang, Z.*; Nishimura, Hiroaki*; Namimoto, Takura*; Fujioka, Shinsuke*; Arikawa, Yasunobu*; Nishikino, Masaharu; Kawachi, Tetsuya; Sagisaka, Akito; Hosoda, Hirokazu*; Orimo, Satoshi; et al.

Review of Scientific Instruments, 83(5), p.053502_1 - 053502_5, 2012/05

 Times Cited Count:16 Percentile:33.88(Instruments & Instrumentation)

X-ray line spectra ranging from 17 to 77 keV were quantitatively measured with a Laue spectrometer, composed of a cylindrically curved crystal and a detector. Either a visible CCD detector coupled with a CsI phosphor screen or an imaging plate can be chosen, depending on the signal intensities and exposure times. The absolute sensitivity of the spectrometer system was calibrated using pre-characterized laser-produced X-ray sources and radioisotopes. The integrated reflectivity for the crystal is in good agreement with predictions by an open code for X-ray diffraction. The energy transfer efficiency from incident laser beams to hot electrons, as the energy transfer agency for specific X-ray line emissions, is derived as a consequence of this work.

Journal Articles

Evaluation of soft X-ray laser with ${it in situ}$ imaging device of high spatial resolution ZnO scintillator

Nakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Sakai, Kohei*; Takeda, Kohei*; Nishi, Ryosuke*; Minami, Yuki*; Cadatal-Raduban, M.*; Sarukura, Nobuhiko*; Nishimura, Hiroaki*; et al.

Japanese Journal of Applied Physics, 50(12), p.122202_1 - 122202_4, 2011/12

 Times Cited Count:9 Percentile:56.93(Physics, Applied)

We demonstrate the potential of a hydrothermal method-grown ZnO as a high-spatial resolution imaging device for in-situ soft X-ray laser diagnostics by characterizing the exciton emission patterns. By plotting the emission pattern radii at each position, we estimated the evolution of the beam radius around the focal point. The beam profile of the Ni-like Ag ion plasma laser was estimated from the waist radii as 29 and 21$$mu$$m, the divergence angle as 7.2 and 11 mrad and the M2 factor as 47 and 50 in the horizontal- and vertical-axis, respectively. Spatial resolution of the magnifier was estimated to be 6$$mu$$m and is expected to improve by optimizing the optics of the magnifier and using a telescope. Our results would enhance the use of ZnO as an imaging device that would play a crucial role in the development and application of soft X-ray light sources.

Journal Articles

Application of laser plasma X-ray beam in radiation biology

Nishikino, Masaharu; Sato, Katsutoshi; Hasegawa, Noboru; Ishino, Masahiko; Kawachi, Tetsuya; Imazono, Takashi; Numasaki, Hodaka*; Teshima, Teruki*; Nishimura, Hiroaki*

X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.301 - 306, 2011/12

Temporal sequences of physical and physicochemical stage of actions in biological systems irradiated with energetic radiation take place with in the order of picoseconds. The short duration of laser produced plasma source could be used as a new source in contrast to conventional X-ray sources in investigating the mechanism of the affect of radiation on biological cells. We have started to develop a focused X-ray beam irradiation system for use in studying radiobiological effects on cells, and demonstrated a preliminary study of radiation effect on culture cells irradiated with laser produced plasma Ka X-rays and the X-ray laser.

Journal Articles

Source development and novel applications of laser-driven plasma X-ray lasers in JAEA

Kawachi, Tetsuya; Hasegawa, Noboru; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Oba, Toshiyuki; Kaihori, Takeshi; Kishimoto, Maki; Ochi, Yoshihiro; Tanaka, Momoko; et al.

X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.15 - 24, 2011/12

This paper reviews recent improvement in the source development of laser-driven X-ray lasers and the applications in the research fields of material science, laser processing, X-ray imaging, and radiation damage in biological cells. In the application for material science, we have firstly observed temporal correlation between the domain structures of ferro-electric substance under the Curie temperature. In the laser processing, new X-ray laser interferometer reveals us the nano-scale surface distortion of substance pumped by a femto-second optical pulse. In the X-ray diffraction image, we have taken several static images of micro-structure of samples: now we are trying to extend the objective to nano-scale dynamics using pump and probe method. In the radiation damage of biological cells, we observed double strand break in DNA using X-ray laser exposure; this results are compared with the case using incoherent several KeV X-ray exposure.

Journal Articles

Measurement of DNA double-strand break yield in human cancer cells by high-current, short-duration bunches of laser-accelerated protons

Yogo, Akifumi; Sato, Katsutoshi; Nishikino, Masaharu; Maeda, Takuya*; Sakaki, Hironao; Hori, Toshihiko*; Ogura, Koichi; Nishiuchi, Mamiko; Teshima, Teruki*; Nishimura, Hiroaki*; et al.

Japanese Journal of Applied Physics, 50(10), p.106401_1 - 106401_7, 2011/10

 Times Cited Count:7 Percentile:64.46(Physics, Applied)

Journal Articles

Condition of MeV electron bunch generated from Argon gas-jet target in the self-modulated laser wakefield regime

Mori, Michiaki; Kando, Masaki; Kotaki, Hideyuki; Hayashi, Yukio; Bulanov, S. V.; Koga, J. K.; Kondo, Kiminori; Pirozhkov, A. S.; Nishimura, Hiroaki*; Nagashima, Keisuke

Journal of the Physical Society of Japan, 80(10), p.105001_1 - 105001_2, 2011/09

 Times Cited Count:3 Percentile:69.39(Physics, Multidisciplinary)

The effects of plasma density and laser power on the energetic electron bunch generation in an Argon (high-Z) gas-jet target in the self modulated laser wakefield acceleration regime were investigated. A vector potential threshold for electron injection was obtained $$a_{rm th}$$ $$sim$$ 2.8 through a simple analytical model include two-dimensional laser pulse compression by relativistic self-focusing, and it is similar to that after accounting for three-dimensional laser pulse compression in the standard Laser Wakefield acceleration regime.

Journal Articles

Status of Japanese design and validation activities of test facilities in IFMIF/EVEDA

Wakai, Eiichi; Kikuchi, Takayuki; Kogawara, Takafumi; Kimura, Haruyuki; Yokomine, Takehiko*; Kimura, Akihiko*; Nogami, Shuhei*; Kurishita, Hiroaki*; Saito, Masahiro*; Nishimura, Arata*; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 6 Pages, 2011/03

Japanese activities of test facilities in IFMIF-EVEDA (International Fusion Materials Irradiation Facility-Engineering Validation and Engineering Design Activities) project have three subjects of engineering design of post irradiation examination (PIE) facilities, small specimen test technique (SSTT), and engineering design of high flux test module (HFTM), and this paper is summarized about present status. Functional analysis and design of 2-D and 3-D models of PIE facility were performed. In HFTM, as materials of heater, W-3Re alloy and/or SiC/SiC composite were selected in the points of high temperature materials, fabrication technology and some suitable properties such as resistance of thermal shock, high temperature re-crystallization, ductility, resistance of irradiation degradation, and low-activation. In SSTT, a test machine of fracture toughness was designed and developed for small specimens with 10 mm square, and it had high accuracy controllability for stress and displacement.

Journal Articles

Efficient multi-keV X-ray generation from a high-Z target irradiated with a clean ultra-short laser pulse

Zhang, Z.*; Nishikino, Masaharu; Nishimura, Hiroaki*; Kawachi, Tetsuya; Pirozhkov, A. S.; Sagisaka, Akito; Orimo, Satoshi; Ogura, Koichi; Yogo, Akifumi; Okano, Yasuaki*; et al.

Optics Express (Internet), 19(5), p.4560 - 4565, 2011/02

 Times Cited Count:16 Percentile:32.97(Optics)

$$Kalpha$$ line emission from Mo and Ag plate were experimentally studied by using ultra-high intensity, clean femtosecond laser pulses. Absolutely yield of $$Kalpha$$ X-rays at 17 keV from Mo and 22 keV from Ag were measured as a function of the laser pulse contrast ratio and irradiation intensity. Significant enhancement of $$Kalpha$$ yields were obtained for both Mo and Ag with higher contrast ratios and high irradiance. The conversion efficiencies of 4.28 $$times$$ 10$$^{-5}$$ /sr for Mo and 4.84 $$times$$ 10$$^{-5}$$ /sr for Ag, the highest values ever obtained, have been demonstarted with the contrast ratio of 10$$^{-10}$$ to 10$$^{-11}$$.

Journal Articles

FIREX project and effects of self-generated electric and magnetic fields on electron-driven fast ignition

Mima, Kunioki*; Sunahara, Atsushi*; Shiraga, Hiroyuki*; Nishimura, Hiroaki*; Azechi, Hiroshi*; Nakamura, Tatsufumi; Jozaki, Tomoyuki*; Nagatomo, Hideo*; Garcia, C.*; Veralde, P.*

Plasma Physics and Controlled Fusion, 52(12), p.124047_1 - 124047_6, 2010/12

 Times Cited Count:9 Percentile:60.86(Physics, Fluids & Plasmas)

Fast ignition is a new scheme in laser fusion, in which higher energy gain with a smaller laser pulse energy is expected. At Osaka University, a laser with four beams and a total output of 10 kJ ps-1, laser for fast ignition experiment (LFEX), has been constructed and we have carried out an integrated experiment with one beam of the LFEX. Through experiments it was found that the coupling efficiency is degraded when the laser pre-pulse is not sufficiently small. Furthermore, the distance between the hot electron source and the core plasma is large. In this paper it is proposed that a thin foil covers the laser entrance of the cone to mitigate the pre-plasma and a double cone reduces the loss of high energy electrons from the side wall of the cone. The simulations indicate that a higher coupling efficiency is expected for the double cone target with a thin foil at the laser entrance.

Journal Articles

Development of laser plasma X-ray microbeam irradiation system and radiation biological application

Sato, Katsutoshi; Nishikino, Masaharu; Numasaki, Hodaka*; Kawachi, Tetsuya; Teshima, Teruki*; Nishimura, Hiroaki*

Denki Gakkai Rombunshi, C, 130(10), p.1800 - 1805, 2010/10

no abstracts in English

Journal Articles

Feasible evaluation of neutron capture therapy for hepatocellular carcinoma using selective enhancement of boron accumulation in tumour with intra-arterial administration of boron-entrapped water-in-oil-in-water emulsion

Yanagie, Hironobu*; Kumada, Hiroaki*; Nakamura, Takemi; Higashi, Shushi*; Ikushima, Ichiro*; Morishita, Yasuyuki*; Shinohara, Atsuko*; Fujiwara, Mitsuteru*; Suzuki, Minoru*; Sakurai, Yoshinori*; et al.

Proceedings of 14th International Congress on Neutron Capture Therapy (ICNCT-14) (CD-ROM), p.157 - 160, 2010/10

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