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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:18 Percentile:62.46(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.
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:18 Percentile:65.23(Optics)line emission from Mo and Ag plate were experimentally studied by using ultra-high intensity, clean femtosecond laser pulses. Absolutely yield of 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 yields were obtained for both Mo and Ag with higher contrast ratios and high irradiance. The conversion efficiencies of 4.28 10/sr for Mo and 4.84 10/sr for Ag, the highest values ever obtained, have been demonstarted with the contrast ratio of 10 to 10.
Sato, Katsutoshi; Nishikino, Masaharu; Okano, Yasuaki*; Oshima, Shinsuke*; Hasegawa, Noboru; Ishino, Masahiko; Kawachi, Tetsuya; Numasaki, Hodaka*; Teshima, Teruki*; Nishimura, Hiroaki*
Radiation Research, 174(4), p.436 - 445, 2010/10
Times Cited Count:16 Percentile:49.45(Biology)Usefulness of laser-plasma X-ray pulse for medical and radiation biological studies was investigated and compared with that of conventional sources such as those obtained from a linear accelerator. A cell irradiation system was developed which uses Copper-K (8 keV) lines from an ultra-short high intensity laser to produce plasma. The absorbed dose of the 8 keV laser-plasma X-ray pulse was accurately estimated with Gafchromic EBT film. When the cells were irradiated with approximately 2 Gy of laser plasma X-ray, the circular regions on -H2AX positive cells could be clearly identified. Moreover, the number of -H2AX and phosphorylated ataxia telangiectasia mutated (ATM) foci induced by 8 keV laser plasma X-ray were comparable to those induced by 4MV X-ray. These results indicate that the laser plasma X-ray source can be useful for radiation biological studies.
Zhang, Z.*; Nishikino, Masaharu; Nishimura, Hiroaki*; Kawachi, Tetsuya; Sagisaka, Akito; Orimo, Satoshi; Ogura, Koichi; Pirozhkov, A. S.; Yogo, Akifumi; Okano, Yasuaki*; et al.
Reza Kenkyu, 38(9), p.698 - 701, 2010/09
Monochromatic X-ray generation from Cu plates was experimentally studied by using a high contrast femtosecond laser pulse. Absolute yield of Ka line at 8 keV was measured as a function of laser pulse contrast ration and irradiation intensity. The conversion efficiency of 8 10/sr, the highest value ever obtained, has been demonstrated at 5.5 10 W/cm with a contrast ratio of 10.
Nishikino, Masaharu; Sato, Katsutoshi; Hasegawa, Noboru; Ishino, Masahiko; Oshima, Shinsuke*; Okano, Yasuaki*; Kawachi, Tetsuya; Numasaki, Hodaka*; Teshima, Teruki*; Nishimura, Hiroaki*
Review of Scientific Instruments, 81(2), p.026107_1 - 026107_3, 2010/02
Times Cited Count:22 Percentile:66.97(Instruments & Instrumentation)An X-ray generation and exposure system dedicated for radiation biology is developed. An X-ray pulse of 8.0 keV in energy as short as 1 ps is generated with a fs-laser pulse, and sample cells are irradiated through a specially designed cell dish with a silicon nitride membrane. DNA double-strand breaks in a nucleus of a human caner cell are caused by X-ray irradiation, and similar DNA breaks are obtained to those with the conventional X-ray source. This result demonstrates feasibility of radiobiological study with a single burst of X-rays shining on a single cell specimen.
Fujisawa, Akihide*; Ido, Takeshi*; Shimizu, Akihiro*; Okamura, Shoichi*; Matsuoka, Keisuke*; Iguchi, Harukazu*; Hamada, Yasuji*; Nakano, Haruhisa*; Oshima, Shinsuke*; Ito, Kimitaka*; et al.
Nuclear Fusion, 47(10), p.S718 - S726, 2007/10
Times Cited Count:100 Percentile:95.33(Physics, Fluids & Plasmas)Present status of experiments on zonal flows is overviewed. Innovative use of modern diagnostics has revealed the existence of zonal flows, their spatio-temporal characteristics, their relationship with turbulence, and their effects on confinement. Particularly a number of observations have been accumulated on the oscillatory branch of the zonal flow, dubbed as geodesic acoustic modes suggesting necessity of theories to give their proper description. Several new methods have elucidated the zonal flow generation processes from the turbulence. Further investigation of relationship between the zonal flows and confinement is strongly encouraged as cross-device activity.
Fujisawa, Akihide*; Ido, Takeshi*; Shimizu, Akihiro*; Okamura, Shoichi*; Matsuoka, Keisuke*; Hamada, Yasuji*; Hoshino, Katsumichi; Nagashima, Yoshihiko*; Shinohara, Koji; Nakano, Haruhisa*; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 12 Pages, 2007/03
Present status of experiments on zonal flows is overviewed. Innovative use of traditional and modern diagnostics has revealed unambiguously the existense of the zonal flows, their spatio-temporal caracteristics, their relationship with turbulence, and their effects on confinement. Particularly, a number of observations have been accumulated on the oscillatory branch of zonal flows, dubbed geodesic acoustic modes, suggesting necessity of theories to give their proper description. Furthur investigation of relationship between zonal flows and confinement is strongly encouraged as cross-device activity.
Nishikino, Masaharu; Okano, Yasuaki*; Sato, Katsutoshi*; Hasegawa, Noboru; Ishino, Masahiko; Oshima, Shinsuke*; Kawachi, Tetsuya; Numasaki, Hodaka*; Teshima, Teruki*; Nishimura, Hiroaki*
no journal, ,
Recently, high energy, monochromatic X-rays emanating from laser-produced plasma (LPP) are attracting much attention as a new radiation source indispensable for high energy density physics, bioscience, and material sciences. Aiming at these applications, we have been improving performances of Ka lines emitted from and soft X-ray lasers. The monochromaticity is particularly important when X-rays are handled with a narrow-band optics or used to selectively excite a specific material involved in matters. In addition, time-duration of such sources is typically an order of pico-second, and it could be comparable or even shorter than recovery time of radiatively-damaged biological cell, so that the LPP source can be a new source for investigating the mechanisms of irradiation survival and death of biological cells. We propose to develop an ultrashort, intense X-ray microbeam system to study the radiobiological effect and the bystander effect.
Nishikino, Masaharu; Ishino, Masahiko; Hasegawa, Noboru; Kawachi, Tetsuya; Sato, Katsutoshi*; Numasaki, Hodaka*; Teshima, Teruki*; Oshima, Shinsuke*; Okano, Yasuaki*; Nishimura, Hiroaki*
no journal, ,
Recently, high energy, monochromatic X-rays emanating from laser-produced plasma (LPP) are attracting much attention as a new radiation source indispensable for high energy density physics, bioscience, and material sciences. Aiming at these applications, we have been improving performances of Ka lines emitted from LPP and soft X-ray lasers (XRLs). The monochromaticity is particularly important when X-rays are handled with a narrowband optics or used to selectively excite a specific material involved in matters. In addition, timeduration of such sources is typically an order of picosecond, and it could be comparable or even shorter than recovery time of radiatively-damaged biological cell, so that the LPP source can be a new source for investigating the mechanisms of irradiation survival and death of biological cells. We propose to develop an ultrashort, intense X-ray microbeam system to study the radiobiological effect and the bystander effect.
Nishikino, Masaharu; Sato, Katsutoshi*; Oshima, Shinsuke*; Hasegawa, Noboru; Ishino, Masahiko; Kawachi, Tetsuya; Okano, Yasuaki*; Numasaki, Hodaka*; Teshima, Teruki*; Nishimura, Hiroaki*
no journal, ,
We have started to develop a laser plasma X-ray microbeam irradiation system, and demonstrated a preliminary study of the cell survival and -H2AX focus formation in the culture cells irradiated with laser-produced plasma X-ray.
Sato, Katsutoshi*; Nishikino, Masaharu; Okano, Yasuaki*; Hasegawa, Noboru; Ishino, Masahiko; Oshima, Shinsuke*; Numasaki, Hodaka*; Kawachi, Tetsuya; Teshima, Teruki*; Nishimura, Hiroaki*
no journal, ,
no abstracts in English
Nishikino, Masaharu; Sato, Katsutoshi; Ishino, Masahiko; Hasegawa, Noboru; Kawachi, Tetsuya; Numasaki, Hodaka*; Teshima, Teruki*; Oshima, Shinsuke*; Nishimura, Hiroaki*
no journal, ,
no abstracts in English
Nishikino, Masaharu; Sato, Katsutoshi; Ishino, Masahiko; Hasegawa, Noboru; Kawachi, Tetsuya; Numasaki, Hodaka*; Teshima, Teruki*; Oshima, Shinsuke*; Nishimura, Hiroaki*
no journal, ,
no abstracts in English
Nishikino, Masaharu; Sato, Katsutoshi; Ishino, Masahiko; Hasegawa, Noboru; Kawachi, Tetsuya; Numasaki, Hodaka*; Teshima, Teruki*; Oshima, Shinsuke*; Nishimura, Hiroaki*
no journal, ,
no abstracts in English
Nishikino, Masaharu; Sato, Katsutoshi; Ishino, Masahiko; Hasegawa, Noboru; Kado, Masataka; Kawachi, Tetsuya; Numasaki, Hodaka*; Teshima, Teruki*; Okano, Yasuaki*; Oshima, Shinsuke*; et al.
no journal, ,
A dedicated radiation biologyn X-ray generation and exposure system has been dedicated for radiation biology is developed. An X-ray pulse of 8.0 keV in energy X-ray pulses is generated with an fs-laser pulse were used to irradiate, and sample cells are irradiated through a custom-made culture dish with a silicon nitride membrane. The X-ray irradiation resulted in DNA double-strand breaks in thea nucleus of a culture cell are caused by X-ray irradiation that were, and similar DNA breaks are obtained to those obtained with athe conventional X-ray source, thus. This result demonstrating thees feasibility of radiobiological studiesy utilizing with a single burst of X-rays focused shining on a single cell specimens.
Nishikino, Masaharu; Zhang, Z.*; Nishimura, Hiroaki*; Kawachi, Tetsuya; Pirozhkov, A. S.; Sagisaka, Akito; Ogura, Koichi; Orimo, Satoshi; Okano, Yasuaki*; Oshima, Shinsuke*; et al.
no journal, ,
no abstracts in English