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Kitayama, Kyo*; Morino, Yu*; Takigawa, Masayuki*; Nakajima, Teruyuki*; Hayami, Hiroshi*; Nagai, Haruyasu; Terada, Hiroaki; Saito, Kazuo*; Shimbori, Toshiki*; Kajino, Mizuo*; et al.
Journal of Geophysical Research; Atmospheres, 123(14), p.7754 - 7770, 2018/07
Times Cited Count:27 Percentile:67.88(Meteorology & Atmospheric Sciences)We compared seven atmospheric transport model results for Cs released during the Fukushima Daiichi Nuclear Power Plant accident. All the results had been submitted for a model intercomparison project of the Science Council of Japan in 2014. We assessed model performance by comparing model results with observed hourly atmospheric concentrations of
Cs, focusing on nine plumes over the Tohoku and Kanto regions. The results showed that model performance for
Cs concentrations was highly variable among models and plumes. We also assessed model performance for accumulated
Cs deposition. Simulated areas of high deposition were consistent with the plume pathways, though the models that best simulated
Cs concentrations were different from those that best simulated deposition. The ensemble mean of all models consistently reproduced
Cs concentrations and deposition well, suggesting that use of a multimodel ensemble results in more effective and consistent model performance.
Oura, Yasuji*; Watanabe, Ryo*; Ebihara, Mitsuru*; Murakami, Yukihiro*; Toh, Yosuke; Kimura, Atsushi; Koizumi, Mitsuo; Furutaka, Kazuyoshi; Oshima, Masumi; Hara, Kaoru; et al.
Journal of Radioanalytical and Nuclear Chemistry, 291(2), p.335 - 339, 2012/02
Times Cited Count:4 Percentile:30.61(Chemistry, Analytical)We applied multiple prompt -ray analysis (MPGA) method to geochemical and cosmochemical samples to evaluate its analytical performance on signal to noise (S/N) ratio, sensitivity, and detection limit. The S/N ratio measured by MPGA system was larger than that by normal prompt
ray activation analysis (PGAA) at JRR3. For some elements, the S/N ratio was improved more than ten times. Several elements that are not detected by PGAA were detected by MPGA. In the present experiment, concentrations of major elements and trace elements with high neutron capture cross section in geochemical and cosmochemical samples were determined accurately by the MPGA system. It is expected that it will determine a lot of trace elements after appropriate adjustments and modifications.
Ishii, Yasuo; Toyoshima, Atsushi; Tsukada, Kazuaki; Asai, Masato; Li, Z.*; Nagame, Yuichiro; Miyashita, Sunao*; Mori, Tomotaka*; Suganuma, Hideo*; Haba, Hiromitsu*; et al.
Bulletin of the Chemical Society of Japan, 84(9), p.903 - 911, 2011/09
Times Cited Count:18 Percentile:49.77(Chemistry, Multidisciplinary)The cation-exchange behavior of element 104, rutherfordium (Rf), was investigated together with its lighter group-4 homologues Zr and Hf, and the tetravalent pseudo-homologue Th in HF/HNO mixed solution. The results demonstrate that distribution coefficients (
) of Rf in HF/0.10 M HNO
decrease with increasing concentration of the fluoride ion [F
], indicating the consecutive formation of fluorido complexes of Rf. We also measured the
values of Rf and the homologues as a function of the hydrogen ion concentration [H
]. The log
values decrease linearly with an increase of log [H
] with slopes between -2.1 and -2.5. This indicates that these elements are likely to form the same chemical compounds: mixture of [MF]
and [MF
]
(M = Rf, Zr, Hf and Th) in the studied solution. It is also ascertained that sequence in the fluoride complex formation is Zr
Hf
Rf
Th.
Toyoshima, Atsushi; Kasamatsu, Yoshitaka*; Tsukada, Kazuaki; Asai, Masato; Ishii, Yasuo; Tome, Hayato*; Nishinaka, Ichiro; Sato, Tetsuya; Nagame, Yuichiro; Schdel, M.; et al.
Journal of Nuclear and Radiochemical Sciences, 11(1), p.7 - 11, 2010/06
The extraction behavior of rutherfordium (Rf) into trioctylphosphine oxide (TOPO) from 2.0 - 7.0 M HCl solution was studied together with that of the homologues Zr and Hf. The extracted yields of Rf, Zr, and Hf increased with an increase of HCl concentration, and the sequence of their extraction was Zr Hf
Rf. It is suggested that the stability of the RfCl
2(TOPO) complex is lower than that of the corresponding species of the homologues.
Kasamatsu, Yoshitaka*; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Li, Z.; Ishii, Yasuo; Tome, Hayato*; Sato, Tetsuya; Kikuchi, Takahiro; Nishinaka, Ichiro; et al.
Chemistry Letters, 38(11), p.1084 - 1085, 2009/10
Times Cited Count:17 Percentile:50.97(Chemistry, Multidisciplinary)We report on the characteristic anion-exchange behavior of the superheavy element dubnium (Db) with atomic number Z = 105 in HF/HNO solution at the fluoride ion concentration [F
] = 0.003 M. The result clearly demonstrates that the fluoro complex formation of Db is significantly different from that of the group-5 homologue Ta in the 6th period of the periodic table while the behavior of Db is similar to that of the lighter homologue Nb in the 5th period.
Tsukada, Kazuaki; Haba, Hiromitsu*; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko*; Kasamatsu, Yoshitaka; Nishinaka, Ichiro; Ichikawa, Shinichi; Yasuda, Kenichiro; Miyamoto, Yutaka; et al.
Radiochimica Acta, 97(2), p.83 - 89, 2009/02
Times Cited Count:22 Percentile:79.08(Chemistry, Inorganic & Nuclear)Anion-exchange chromatography of element 105, dubnium (Db), produced in the Cm(
F, 5n)
Db reaction is investigated together with the homologues Nb and Ta, and the pseudo-homologue Pa in 13.9 M hydrofluoric acid (HF) solution. The distribution coefficient (K
) of Db on an anion-exchange resin is successfully determined by running cycles of the 1702 chromatographic column separations. The result clearly indicates that the adsorption of Db on the resin is significantly different from that of the homologues and that the adsorption of anionic fluoro complexes of these elements decreases in the sequence of Ta
Nb
Db
Pa.
Ishii, Yasuo; Toyoshima, Atsushi; Tsukada, Kazuaki; Asai, Masato; Tome, Hayato; Nishinaka, Ichiro; Nagame, Yuichiro; Miyashita, Sunao*; Mori, Tomotaka*; Suganuma, Hideo*; et al.
Chemistry Letters, 37(3), p.288 - 289, 2008/03
Times Cited Count:21 Percentile:55.45(Chemistry, Multidisciplinary)We have investigated cation-exchange behavior of Rf together with the lighter homologues of the group-4 elements Zr and Hf, and the tetravalent pseudo-homologue Th, in HF/HNO solution using Automated Ion exchange separation apparatus coupled with the Detection system for Alpha spectroscopy (AIDA). The
values of Zr, Hf, Th and Rf in HF/0.1 M HNO
were decreased with increasing the concentration of the fluoride ion [F
], indicating the formation of the fluoride complexes. The sequence of the fluoride complexation strength is Zr
Hf
Rf
Th.
Toyoshima, Atsushi; Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Akiyama, Kazuhiko*; Goto, Shinichi*; Ishii, Yasuo; Nishinaka, Ichiro; Sato, Tetsuya; Nagame, Yuichiro; et al.
Radiochimica Acta, 96(3), p.125 - 134, 2008/03
Times Cited Count:29 Percentile:84.79(Chemistry, Inorganic & Nuclear)Formation of an anionic fluoride-complex of element 104, rutherfordium (Rf) produced in the Cm(
O,5n)
Rf reaction was studied by an anion-exchange method based on an atom-at-a-time scale. It was found that the hexafluoro complex of Rf, [RfF
]
, was formed in the studied fluoride ion concentrations of 0.0005 - 0.013 M. Formation of [RfF
]
was significantly different from that of the homologues Zr and Hf, [ZrF
]
and [HfF
]
; the evaluated formation constant of [RfF
]
is at least one-order of magnitude smaller than those of [ZrF
]
and [HfF
]
.
Chai, J.; Miyamoto, Yutaka; Kokubu, Yoko; Magara, Masaaki; Sakurai, Satoshi; Usuda, Shigekazu; Oura, Yasuji*; Ebihara, Mitsuru*
Journal of Radioanalytical and Nuclear Chemistry, 272(2), p.397 - 401, 2007/05
Times Cited Count:2 Percentile:18.31(Chemistry, Analytical)Cm is an important nuclide because it has the next-shortest half-life (1.6
10
yr) from
Pu among the transuranic nuclides. The disintegration of
Cm to
U by three
decays and two
decays and the chemical fractionation between Cm and U during the formation of solid materials in early solar system lead to changes in the ratios of
U to
U. This variation may provide strict constraints on the time interval between the last r-process nucleosynthetic event and the formation of the solar system. It is important to develop a practical analysis protocol to determine the isotope ratio of trace uranium in geochemical and environment samples. As uranium is the least abundant element in our solar system, analytical techniques with high sensitivity and precision are required. In this study, a double focusing inductively coupled plasma mass spectory was applied to measure isotopic ratio of uranium. By one set data obtained from the EDTA phase of the Jilin meteorite sample, the upper limit of
Cm in the early solar system was calculated and
Cm/
U
0.003 was obtained.
Oshima, Masumi; Toh, Yosuke; Kimura, Atsushi; Ebihara, Mitsuru*; Oura, Yasuji*; Ito, Yasuo*; Sawahata, Hiroyuki*; Matsuo, Motoyuki*
Journal of Radioanalytical and Nuclear Chemistry, 271(2), p.317 - 321, 2007/02
Times Cited Count:11 Percentile:60.02(Chemistry, Analytical)By combining neutron activation analysis with multiple -ray detection, we have proved better sensitivity and resolution for the trace element analysis than the ordinary single
-ray detection method. We now try to apply the multiple
-ray detection method to the prompt
-ray analysis (PGA). We have established a new cold neutron beam line for PGA in Japan Research Reactor, JRR-3M, at Tokai establishment of Japan Atomic Energy Research Institute(JAERI). It consists of a beam shutter, a beam attenuator, a
-ray detector array, a sample changer, and a beam stopper. We construct a high-efficiency
-ray detector array specially designed for this purpose. Its performance has been evaluated with the Monte Carlo simulation code, GEANT 4.5.0.
Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Ishii, Yasuo; Tome, Hayato; Sato, Tetsuya; Nishinaka, Ichiro; Ichikawa, Takatoshi; Ichikawa, Shinichi; et al.
Radiochimica Acta, 95(1), p.1 - 6, 2007/01
Times Cited Count:16 Percentile:71.08(Chemistry, Inorganic & Nuclear)no abstracts in English
Asai, Masato; Tsukada, Kazuaki; Ichikawa, Shinichi; Sakama, Minoru*; Haba, Hiromitsu*; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Kojima, Yasuaki*; Oura, Yasuji*; et al.
Physical Review C, 73(6), p.067301_1 - 067301_4, 2006/06
Times Cited Count:21 Percentile:75.45(Physics, Nuclear)no abstracts in English
Asai, Masato; Tsukada, Kazuaki; Sakama, Minoru*; Ichikawa, Shinichi; Ishii, Tetsuro; Nagame, Yuichiro; Nishinaka, Ichiro; Akiyama, Kazuhiko; Osa, Akihiko; Oura, Yasuji*; et al.
Physical Review Letters, 95(10), p.102502_1 - 102502_4, 2005/09
Times Cited Count:64 Percentile:87.46(Physics, Multidisciplinary)Excited states in Fm fed by the
decay of
No have been established through
-
and
-electron coincidence spectroscopy using a gas-jet transport system and an on-line isotope separator. The spin-parity of the 124.1 keV level in
Fm has been identified on the basis of the measured internal conversion coefficients. The
configuration has been assigned to the ground state of
No as well as to the 124.1 keV level. It was found that the ground state configuration of
No is different from that of lighter
isotones.
Asai, Masato; Sakama, Minoru*; Tsukada, Kazuaki; Ichikawa, Shinichi; Haba, Hiromitsu*; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Kojima, Yasuaki*; Oura, Yasuji*; et al.
European Physical Journal A, 23(3), p.395 - 400, 2005/02
Times Cited Count:16 Percentile:70.78(Physics, Nuclear)The EC decay of Am has been studied through
-ray spectroscopy. Two EC-decaying states have been found in
Am with half-lives of 3.6 min and 2.9 min. In
Pu, we have found the
octupole band and two-quasiparticle states one of which is a
isomer with a 1.2
s half-life. The EC transitions from
Am to the two-quasiparticle states in
Pu show small
values of 4.8--5.3, which allowed us to assign proton-neutron configurations of
Am and the two-quasiparticle states.
Nagame, Yuichiro; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko; Ishii, Yasuo; Sato, Tetsuya; Hirata, Masaru; Nishinaka, Ichiro; Ichikawa, Shinichi; et al.
Radiochimica Acta, 93(9-10), p.519 - 526, 2005/00
Times Cited Count:31 Percentile:87.08(Chemistry, Inorganic & Nuclear)no abstracts in English
Asai, Masato; Sakama, Minoru*; Tsukada, Kazuaki; Ichikawa, Shinichi; Haba, Hiromitsu*; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Kojima, Yasuaki*; Oura, Yasuji*; et al.
European Physical Journal A, 22(3), p.411 - 416, 2004/12
Times Cited Count:9 Percentile:50.77(Physics, Nuclear)EC and decays of
Am have been studied by means of
-ray spectroscopy. Excited states in
Pu have been established for the first time, and tentative spin-parity and Nilsson assignments were given to these levels. The ground state of
Am was evaluated to be the
state from the experimental results. It was found that the
state in
Np is located at
15~keV, which allowed us to determine the
value of
Am as 6569
~keV, in combination with the measured
-particle energy.
Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko; Nishinaka, Ichiro; Hirata, Masaru; Yaita, Tsuyoshi; Ichikawa, Shinichi; Nagame, Yuichiro; et al.
Journal of the American Chemical Society, 126(16), p.5219 - 5224, 2004/04
Times Cited Count:44 Percentile:72.53(Chemistry, Multidisciplinary)Fluoride complexation of element 104, rutherfordium (Rf), produced in the Cm(
O,5n)
Rf reaction has been studied by anion-exchange chromatography on an atom-at-a-time scale. The anion-exchangechromatographic behavior of Rf was investigated in 1.9-13.9 M hydrofluoric acid together with those of the group-4 elements Zr and Hf produced in the
O-induced reactions on Ge and Gd targets, respectively. It was found that the adsorption behavior of Rf on anion-exchange resin is quite different from those of Zr and Hf, suggesting the influence of relativistic effect on the fluoride complexation of Rf.
Sakama, Minoru*; Asai, Masato; Tsukada, Kazuaki; Ichikawa, Shinichi; Nishinaka, Ichiro; Nagame, Yuichiro; Haba, Hiromitsu*; Goto, Shinichi*; Shibata, Michihiro*; Kawade, Kiyoshi*; et al.
Physical Review C, 69(1), p.014308_1 - 014308_11, 2004/01
Times Cited Count:23 Percentile:75.43(Physics, Nuclear)no abstracts in English
Asai, Masato; Tsukada, Kazuaki; Ichikawa, Shinichi; Sakama, Minoru*; Haba, Hiromitsu*; Nagame, Yuichiro; Nishinaka, Ichiro; Akiyama, Kazuhiko; Toyoshima, Atsushi; Kaneko, Tetsuya*; et al.
European Physical Journal A, 16(1), p.17 - 19, 2003/01
Times Cited Count:8 Percentile:49.79(Physics, Nuclear)The new isotope Bk has been identified for the first time using a gas-jet coupled on-line isotope separator at the JAERI tandem accelerator facility. Characteristic X rays and three
transitions associated with the EC decay of
Bk have been observed, and the half-life was determined to be 4.6 min. The half-life value and the observed
-ray energies and intensities can be consistently explained as a consequence of the allowed EC transition of
.
Sakama, Minoru*; Tsukada, Kazuaki; Asai, Masato; Ichikawa, Shinichi; Haba, Hiromitsu; Goto, Shinichi*; Nishinaka, Ichiro; Nagame, Yuichiro; Oura, Yasuji*; Kojima, Yasuaki*; et al.
Journal of Nuclear Science and Technology, 39(Suppl.3), p.34 - 37, 2002/11
no abstracts in English