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Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.
Journal of Environmental Radioactivity, 238-239, p.106721_1 - 106721_10, 2021/11
Times Cited Count：11 Percentile：56.59(Environmental Sciences)This study was aimed at analysing performance of models for radiocesium migration mainly in evergreen coniferous forest in Fukushima, by inter-comparison between models of several research teams. The exercise included two scenarios of countermeasures against the contamination, namely removal of soil surface litter and forest renewal, and a specific konara oak forest scenario in addition to the evergreen forest scenario. All the models reproduced trend of time evolution of radiocesium inventories and concentrations in each of the components in forest such as leaf and organic soil layer. However, the variations between models enlarged in long-term predictions over 50 years after the fallout, meaning continuous field monitoring and model verification/validation is necessary.
Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Togashi, Tadashi*; Fukami, Kenji*; et al.
Journal of Physics B; Atomic, Molecular and Optical Physics, 46(16), p.164006_1 - 164006_6, 2013/08
Times Cited Count：3 Percentile：19.06(Optics)By introducing 13th- (61.7 nm) and 15th-order harmonics (53.4 nm) of femtosecond laser pulses at 800 nm into an undulator of SCSS (SPring-8 Compact SASE Source) test accelerator at RIKEN, these harmonic pulses were amplified by a factor of more than 10
with a high contrast ratio through the interaction between accelerated electron bunches and the harmonic pulses. From numerical simulations of the amplification processes of high-order harmonic pulses in the undulator, optimum conditions of the electron bunch duration interacting with the high-order harmonic pulses were investigated for generating full-coherent and intense pulses in the extreme ultraviolet wavelength region.
Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Okino, Tomoya*; Yamanouchi, Kaoru*; et al.
Optics Express (Internet), 19(1), p.317 - 324, 2011/01
Times Cited Count：96 Percentile：96.45(Optics)The 13th harmonic of a Ti:sapphire (Ti:S) laser in the plateau region was injected as a seeding source to a 250-MeV free-electron-laser (FEL) amplifier. When the amplification conditions were fulfilled, strong enhancement of the radiation intensity by a factor of 650 was observed. The random and uncontrollable spikes, which appeared in the spectra of the Self-Amplified Spontaneous Emission (SASE) based FEL radiation without the seeding source, were found to be suppressed drastically to form to a narrow-band, single peak profile at 61.2 nm. The properties of the seeded FEL radiation were well reproduced by numerical simulations. We discuss the future precept of the seeded FEL scheme to the shorter wavelength region.
Ohashi, Hayato*; Suda, Shintaro*; Tanuma, Hajime*; Fujioka, Shinsuke*; Nishimura, Hiroaki*; Nishihara, Katsunobu*; Kai, Takeshi; Sasaki, Akira; Sakaue, Hiroyuki*; Nakamura, Nobuyuki*; et al.
Journal of Physics; Conference Series, 163, p.012071_1 - 012071_4, 2009/06
Times Cited Count：7 Percentile：89.27(Physics, Multidisciplinary)Extreme ultra-violet (EUV) emission spectra of multiply charged tin ions were measured in the wavelength range of 10-22 nm following charge exchange collisions or the electron impact excitation of tin ions. In charge exchange collisions, we observed both the resonance lines and the emission lines corresponding to the transitions between the excited states. On the other hand, we observed mainly the resonance lines in the electron impact experiments. We can distinguish the resonance lines from other emission lines in the charge exchange spectrum by comparison with the emission lines in the electron impact spectrum.
Suzuki, Chihiro*; Kato, Takako*; Sato, Kuninori*; Tamura, Naoki*; Kato, Daiji*; Sudo, Shigeru*; Yamamoto, Norimasa*; Tanuma, Hajime*; Ohashi, Hayato*; Suda, Shintaro*; et al.
Journal of Physics; Conference Series, 163, p.012019_1 - 012019_4, 2009/06
Times Cited Count：11 Percentile：94.18(Physics, Multidisciplinary)We have measured EUV spectra from highly charged tin ions in low density plasmas produced in the Large Helical Device (LHD). The well known dense spectral structure around 13.5 nm is measured when the plasma is rapidly cooled and approaching radioactive collapse, while the sparse spectrum with several unidentified discrete lines from 13.8-14.6 nm is observed if the plasma is cooled more slowly. The dominant charge states in the former case are Sn
-Sn
. The latter case may be explained by considering the spectral lines from charge states higher than Sn
.
Nasu, Shoichi*; Nagata, Shinji*; Yoshii, Kiichiro*; Takahiro, Katsumi*; Kikuchi, Naoto*; Kusano, Eiji*; Moto, Shintaro*; Yamaguchi, Sadae*; Ohashi, Kentaro*; Noda, Kenji; et al.
Funtai Oyobi Fummatsu Yakin, 52(6), p.427 - 429, 2005/06
no abstracts in English
Miyamoto, Yoshiaki; Ogawa, Masuro; Akino, Norio; Shiina, Yasuaki; Inagaki, Yoshiyuki; Shimizu, Saburo; Onuki, Kaoru; Ishiyama, Shintaro; Katanishi, Shoji; Takeda, Tetsuaki; et al.
JAERI-Review 2001-006, 147 Pages, 2001/03
JAERI-Review-2001-006.pdf:9.2MB
no abstracts in English
Hirai, Keizo*; Komatsu, Masafumi*; Akama, Akio*; Noguchi, Ryotaro*; Nagakura, Junko*; Ohashi, Shinta*; Saito, Tetsu*; Kawasaki, Tatsuro*; Yazaki, Kenichi*; Ikeda, Shigeto*; et al.
no journal, ,
no abstracts in English
Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.
no journal, ,
We applied modelling approaches to evaluate the past and future dynamics of 
Cs in forests. In the model inter-comparison exercise using Fukushima data, six models with diverse model structures, processes, parameters and numerical approaches joined this exercise and the performance and uncertainties of the state-of-the-art models were explored. The inter-comparison revealed that, after appropriate calibration, the models reproduced the observed data reliably and the ranges of calculated trajectories were narrow in the early phase after the fallout. However, the envelope of the calculated model end points enlarged in long-term simulations over 50 years after the fallout. The model-inter comparison exercise emphasizes the importance of decadal data for various forest types and repetitive verification/validation processes using holistic, long-term data to improve the models and to update the forecasting capacity of the models.
