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Yasuda, Takako*; Oda, Shoji*; Asaka, Tomomi*; Funayama, Tomoo; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Yasuhiko; Mitani, Hiroshi*
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 85, 2015/03
In this present study, we examined the effects of heavy carbon-ions on development in pre-implantation period utilizing medaka blastula stage embryos (st. 11: blastderm diameter is about 500 m). We performed targeted irradiation by carbon-ion micro-beam (diameters of 120, 180 m) to a central parts of blastoderm and observed the abnormalities during development compared with whole-body irradiated embryos. As a results, retardation and characteristic malformed eyes were observed during development when blastoderm cells were partially irradiated, However, more than half of 50 Gy-irradiated embryos (area size=120 m diameter) could hatch normally in contrast to all embryos with 2 Gy of whole-body irradiation being lethal before hutching.
Sakai, Seiji; Mitani, Seiji*; Matsumoto, Yoshihiro; Entani, Shiro; Avramov, P.; Otomo, Manabu; Naramoto, Hiroshi*; Takanashi, Koki
Journal of Magnetism and Magnetic Materials, 324(12), p.1970 - 1974, 2012/06
Times Cited Count:3 Percentile:14.91(Materials Science, Multidisciplinary)Sakai, Seiji; Mitani, Seiji*; Sugai, Isamu; Takanashi, Koki; Matsumoto, Yoshihiro; Entani, Shiro; Naramoto, Hiroshi*; Avramov, P.; Maeda, Yoshihito
Physical Review B, 83(17), p.174422_1 - 174422_6, 2011/05
Times Cited Count:8 Percentile:36.17(Materials Science, Multidisciplinary)Sugai, Isamu*; Sakai, Seiji; Matsumoto, Yoshihiro; Naramoto, Hiroshi*; Mitani, Seiji*; Takanashi, Koki; Maeda, Yoshihito
Journal of Applied Physics, 108(6), p.063920_1 - 063920_7, 2010/09
Times Cited Count:8 Percentile:34.38(Physics, Applied)Matsumoto, Yoshihiro; Sakai, Seiji; Takagi, Yasumasa*; Nakagawa, Takeshi*; Yokoyama, Toshihiko*; Shimada, Toshihiro*; Mitani, Seiji*; Naramoto, Hiroshi*; Maeda, Yoshihito
Chemical Physics Letters, 470(4-6), p.244 - 248, 2009/03
Times Cited Count:17 Percentile:51.33(Chemistry, Physical)Electronic and spin states of the codeposited C-Co films with large tunnel magnetoresistance (TMR) effect were investigated with the X-ray absorption and magnetic circular dichroism (MCD) spectroscopies. It is revealed that a C-Co compound generated in the C-Co films shows the clear MCD signal attributed to the spin-polarized Co 3d states hybridized with C orbitals. The magnetic response of these Co 3d-derived states agrees well with temperature dependence of the observed MR ratios of the granular C-Co films. This suggests the incorporation of the spin-polarized Co 3d-derived states of the C-Co compound into the observed TMR effect.
Nakazato, Tomoharu*; Furukawa, Yusuke*; Tanaka, Momoko; Tatsumi, Toshihiro*; Nishikino, Masaharu; Yamatani, Hiroshi*; Nagashima, Keisuke; Kimura, Toyoaki*; Murakami, Hidetoshi*; Saito, Shigeki*; et al.
Journal of Crystal Growth, 311(3), p.875 - 877, 2009/01
Times Cited Count:24 Percentile:86.17(Crystallography)The temperature dependence of scintillation properties of a hydrothermal-method-grown zinc oxide (ZnO) emission is investigated using a nickel-like silver laser emitting at 13.9 nm. A broad peak at 386 nm with a full-width at half-maximum (FWHM) of 15 nm at room temperature (298 K) is obtained. The peak position tends to be blue shifted while the FWHM becomes narrower when the crystal temperature is decreased to 25 K. Streak images fitted by a double exponential decay reveal that the measured emission decay at 105 K was = 0.88 ns and = 2.7 ns. This decay time of a few nanoseconds is suitable for lithographic applications and is sufficiently short for the characterization of laser plasma extreme ultraviolet (EUV) sources with nanosecond durations.
Furukawa, Yusuke*; Tanaka, Momoko; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Yamatani, Hiroshi; Nishimura, Hiroaki*; Mima, Kunioki*; Kagamitani, Yuji*; et al.
Reza Kenkyu, 36(APLS), p.1028 - 1030, 2008/12
Optical technologies in extreme ultraviolet (EUV) region have been receiving strong interests for the next generation lithography. Here we report properties of ZnO as scintillators in the EUV region, and to demonstrate the feasibility of using a Ni-like Ag EUV laser operated at 13.9-nm to evaluate these properties. The ZnO sample was irradiated with EUV laser pulses and the fluorescence was measured using a streak camera fitted with a spectrograph. A clear, excitonic, fluorescence peak was observed at around 380 nm with a decay lifetime of 3 ns. The prominent peak fluorescence is ideal for EUV detection and further applications including imaging.
Furukawa, Yusuke*; Tanaka, Momoko; Nakazato, Tomoharu*; Tatsumi, Toshihiro*; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; Kimura, Toyoaki; Murakami, Hidetoshi*; Saito, Shigeki*; et al.
Journal of the Optical Society of America B, 25(7), p.B118 - B121, 2008/07
Times Cited Count:24 Percentile:72.65(Optics)Using EUV laser operated at 13.9 nm ZnO and GaN are shown to be excellent scintillators in this wavelength region. Especially ZnO has short response time of 3 ns and prominent peak fluorescence from excitation at 380 nm.
Tanaka, Momoko; Furukawa, Hiroyuki*; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; Kagamitani, Yuji*; Ehrentraut, D.*; et al.
Journal of Physics; Conference Series, 112(4), p.042058_1 - 042058_4, 2008/00
Times Cited Count:1 Percentile:55.21(Physics, Fluids & Plasmas)Optical technologies in the extreme ultraviolet (EUV) region have been receiving strong interest for the next generation lithography. Efficient and fast scintillators are one of the key devices functioning in the EUV region. In this paper, we report excellent properties of ZnO and GaN as scintillators in the EUV region, and to demonstrate the feasibility of using a Ni-like Ag EUV laser operated at 13.9-nm to evaluate these properties. The sample was irradiated with EUV laser pulses, and the fluorescence spectrum and the fluorescence lifetime were measured using a streak camera fitted with a spectrograph. In the case of ZnO, a clear, excitonic, fluorescence peak was observed at around 380 nm with a decay lifetime of 3 ns. For GaN, a fluorescence peak at 370 nm having slower 5-ns decay time was observed. In this respect, the EUV scintillation properties of ZnO is said to be more favorable than GaN.
Tanaka, Momoko; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; Kimura, Toyoaki; Furukawa, Yusuke*; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishimura, Hiroaki*; et al.
Applied Physics Letters, 91(23), p.231117_1 - 231117_3, 2007/12
Times Cited Count:52 Percentile:84.56(Physics, Applied)The scintillation properties of a hydrothermal method grown zinc oxide (ZnO) crystal are evaluated for extreme ultraviolet (EUV) laser excitation at 13.9 nm wavelength. The exciton emission lifetime at around 380 nm is determined to be 1.1 ns, almost identical to ultraviolet laser excitation cases. This fast response time is sufficiently short for characterizing EUV lithography light sources having a few nanoseconds duration. The availability of large size ZnO crystal up to 3-inch is quite attractive for future lithography and imaging applications.
Sakai, Seiji; Sugai, Isamu; Mitani, Seiji*; Takanashi, Koki; Matsumoto, Yoshihiro; Naramoto, Hiroshi*; Avramov, P.; Okayasu, Satoru; Maeda, Yoshihito
Applied Physics Letters, 91(24), p.242104_1 - 242104_3, 2007/12
Times Cited Count:30 Percentile:71.82(Physics, Applied)Sakai, Seiji; Yakushiji, Kei*; Mitani, Seiji*; Sugai, Isamu; Takanashi, Koki*; Naramoto, Hiroshi*; Avramov, P.; Lavrentiev, V.*; Narumi, Kazumasa; Maeda, Yoshihito
Materials Transactions, 48(4), p.754 - 758, 2007/04
Times Cited Count:9 Percentile:51.33(Materials Science, Multidisciplinary)Magnetic properties were investigated for the alternately deposited film of C and Co which has found to exhibit tunnel magnetoresistance (MR) of 10-80 %. Magnetic field and temperature dependences of magnetization showed typical superparamagnetic behaviors with the blocking temperature of 40 K. The magnetization curve at 300 K was well fitted by the Langevin function with the size distribution of Co particles, and the mean diameter and size distribution were evaluated to be 3.1 nm and 1 nm, respectively. Based on the magnetic properties, the detailed structure and magnetotransport properties are discussed.
Sakai, Seiji; Yakushiji, Kei*; Mitani, Seiji*; Takanashi, Koki*; Naramoto, Hiroshi; Avramov, P.; Narumi, Kazumasa; Lavrentiev, V.; Maeda, Yoshihito
Applied Physics Letters, 89(11), p.113118_1 - 113118_3, 2006/09
Times Cited Count:59 Percentile:86.21(Physics, Applied)In this study, the first results are described on the spin-dependent transport in the Co-C hybrid film in which Co nanoparticles are dispersed in a matrix of the Co-C compound. It is found that the hybrid film shows significant tunnel magnetoresistance (MR) of a few 10 %, which is comparable to granular metal-insulator systems, under the small applied bias voltage. Additionally, it is found that the electrical conductivity and MR ratio are strongly influenced by the bias voltage and the MR ratio under the higher bias voltage reaches 80%, which is anomalously high in granular systems. The bias-dependent magnetotransport behaviours are surmised to be related to the electronic structure of the Co-C compound.
Hirota, Jitsuya; Kuroi, Hideo; Goto, Yorio; Furuhashi, Akira; Yasuno, Takehiko; Yamamoto, Ken; Mitani, Hiroshi; Obu, Makoto; Ichimori, Toshihiro; Koyama, Kinji; et al.
JAERI 1034, 50 Pages, 1962/08
no abstracts in English
Sakai, Seiji; Yakushiji, Kei*; Naramoto, Hiroshi; Narumi, Kazumasa; Mitani, Seiji*; Takanashi, Koki*
no journal, ,
no abstracts in English
Sakai, Seiji; Sugai, Isamu; Yakushiji, Kei*; Mitani, Seiji*; Takanashi, Koki*; Naramoto, Hiroshi; Avramov, P.; Narumi, Kazumasa; Maeda, Yoshihito
no journal, ,
no abstracts in English
Sakai, Seiji; Sugai, Isamu; Yakushiji, Kei*; Mitani, Seiji*; Takanashi, Koki*; Naramoto, Hiroshi; Avramov, P.; Narumi, Kazumasa; Maeda, Yoshihito
no journal, ,
We have revealed that the Co/Co-C films prepared by alt-deposition show the tunnel MR of a few 10% under low bias voltage and the further enhancement to above 80% by the voltage increase at lower temperature than 10 K. In the present study, the magnetotransport properties in the co-deposited Co/Co-C films are reported. The co-deposited film shows the remarkable tunnel MR effect (10-50%) whose ratio is significantly influenced by the applied voltage. Such a significant MR enhancement by the bias-voltage is found to take place commonly in the Co/Co-C films irrespective of the deposition method, and that is in contrast to the small extent of changes in the conventional metal/insulator systems. In the presentation, the comparative results for the co-deposited and alt-deposited Co/Co-C films are also reported in comparison with the analyzed structures by Raman spectroscopy et al..
Sakai, Seiji; Sugai, Isamu*; Mitani, Seiji*; Takanashi, Koki*; Naramoto, Hiroshi*; Avramov, P.; Okayasu, Satoru; Narumi, Kazumasa; Maeda, Yoshihito
no journal, ,
no abstracts in English
Furukawa, Yusuke*; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishimura, Hiroaki*; Mima, Kunioki*; Tanaka, Momoko; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; et al.
no journal, ,
Zinc oxide (ZnO) has previously been reported to be a potential light-emitting diode materia. We measured the time-resolved emission spectrum of a ZnO crystal for extreme ultraviolet (EUV) laser excitation at 13.9 nm wavelength and compared with UV excitation case. The emission lifetime was determined to be 2.6 ns. This value was not changed even for ultraviolet laser excitation. In the context of the nanosecond regime in the EUV region, ZnO crystal promises to be a feasible scintillation material.
Sakai, Seiji; Sugai, Isamu; Mitani, Seiji*; Matsumoto, Yoshihiro; Takanashi, Koki; Naramoto, Hiroshi*; Okayasu, Satoru; Maeda, Yoshihito
no journal, ,
no abstracts in English