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Journal Articles

Ground-state configuration of the $$N=157$$ nucleus $$^{259}$$No

Asai, Masato; Tsukada, Kazuaki; Sakama, Minoru*; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Ishii, Yasuo; Toyoshima, Atsushi; Ishii, Tetsuro; Nishinaka, Ichiro; Nagame, Yuichiro; et al.

Physical Review C, 87(1), p.014332_1 - 014332_6, 2013/01

 Times Cited Count:6 Percentile:43.85(Physics, Nuclear)

The spin-parity and neutron configuration of the ground state of $$^{259}$$No have been identified through $$alpha$$-decay spectroscopy. The $$^{259}$$No is the nucleus with the largest neutron number whose spin-parities and single-particle configurations have ever been identified. The neutron 9/2$$^{+}$$[615] configuration was assigned to the ground state of $$^{259}$$No as well as to the 231.4 keV level in $$^{255}$$Fm. This allowed us to establish energy spacings and order of the neutron single-particle orbitals in such heaviest nuclear region. The appearance of the 9/2$$^{+}$$[615] ground state at $$N$$=157 implies that the order of the neutron orbitals between the $$N$$=152 and 162 deformed shell gaps should change considerably with increasing neutron number.

JAEA Reports

Study on validation method of regional groundwater flow model; Case study for Boso peninsula

Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo; Ichikawa, Yasuo*; Nakamura, Masaru*

JAEA-Research 2010-066, 20 Pages, 2011/03

JAEA-Research-2010-066.pdf:2.26MB

In the safety assessment for a geological disposal of radioactive waste, it is important to establish modelling methods and validation methods for regional groundwater flow system in the depth of 300$$sim$$1000m to estimate radionuclide migration to human environment through groundwater flow system. The study discussed application of data and assessment methods for model validation based on multiple indicators such as hydrology, groundwater chemistry, temperature and age of groundwater in case of the Boso Peninsula in Chiba Prefecture where a lot of in-situ data about groundwater was measured. This results show that existing hydrochemical and thermal data are applicable to explain freshwater and saltwater distribution and groundwater flow pattern in case of regional scale. It also indicates that gravitational groundwater is likely to flow into the deep part of fresh-saltwater interface based on the exist of Na-HCO$$_{3}$$ type water above fresh-saltwater interface mixed with meteoric water and that multiple indicators are applicable to evaluate groundwater flow property and groundwater flow boundary in case of site scale region.

Journal Articles

Neutron one-quasiparticle states in $$^{251}$$Fm$$_{151}$$ populated via the $$alpha$$ decay of $$^{255}$$No

Asai, Masato; Tsukada, Kazuaki; Haba, Hiromitsu*; Ishii, Yasuo; Ichikawa, Takatoshi*; Toyoshima, Atsushi; Ishii, Tetsuro; Nagame, Yuichiro; Nishinaka, Ichiro; Kojima, Yasuaki*; et al.

Physical Review C, 83(1), p.014315_1 - 014315_12, 2011/01

 Times Cited Count:23 Percentile:79.3(Physics, Nuclear)

Excited states in $$^{251}$$Fm populated via the $$alpha$$ decay of $$^{255}$$No are studied in detail through $$alpha$$-$$gamma$$ coincidence and $$alpha$$ fine structure measurements. Spin-parities and neutron configurations of the excited states in $$^{251}$$Fm as well as the ground state of $$^{255}$$No are definitely identified on the basis of deduced internal conversion coefficients, lifetimes of $$gamma$$ transitions, rotational-band energies built on one-quasiparticle states, and hindrance factors of $$alpha$$ transitions. It is found that the excitation energy of the 1/2$$^{+}$$[620] state in $$N$$=151 isotones increases with the atomic number, especially at $$Z$$$$ge$$100, while that of the 1/2$$^{+}$$[631] state decreases at $$Z$$=100. Energy systematics of the one-quasiparticle states in the $$N$$=151 isotones are discussed in terms of the evolution of nuclear deformation involving the hexadecapole and hexacontatetrapole deformations.

Journal Articles

Extraction behavior of rutherfordium into tributylphosphate from hydrochloric acid

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:15 Percentile:70.38(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Chemical studies on rutherfordium (Rf) at JAERI

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:29 Percentile:87.12(Chemistry, Inorganic & Nuclear)

no abstracts in English

JAEA Reports

The Research of chemical composition in the rock near the fault

Miwa, Atsushi*; Kurosawa, Hideki*; Ichikawa, Yasuo*

JNC TJ7420 2005-097, 60 Pages, 2002/03

JNC-TJ7420-2005-097.pdf:18.2MB

Macro- and microscopic structures of the fault rocks included in the core from the 389.52m borehole across the Nojima Fault are described to show the groundwater flow model around the underground fracture zone.

Oral presentation

Formation of anionic chloride complex of Rutherfordium (Rf)

Tsukada, Kazuaki; Toyoshima, Atsushi; Haba, Hiromitsu*; Asai, Masato; Akiyama, Kazuhiko*; Ishii, Yasuo; Tome, Hayato*; Nishinaka, Ichiro; Sato, Tetsuya; Ichikawa, Takatoshi; et al.

no journal, , 

no abstracts in English

Oral presentation

TBP reversed-phase extraction chromatography of Rutherfordium in the HCl solution

Toyoshima, Atsushi; Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Akiyama, Kazuhiko*; Ishii, Yasuo; Tome, Hayato*; Nishinaka, Ichiro; Sato, Tetsuya; Ichikawa, Takatoshi; et al.

no journal, , 

no abstracts in English

Oral presentation

Chloride complex formation of Rf in HCl and CH$$_{3}$$OH mixed solution

Tsukada, Kazuaki; Toyoshima, Atsushi; Haba, Hiromitsu*; Asai, Masato; Akiyama, Kazuhiko*; Ishii, Yasuo; Tome, Hayato; Nishinaka, Ichiro; Sato, Tetsuya; Ichikawa, Shinichi; et al.

no journal, , 

no abstracts in English

Oral presentation

Study of lomg-term regional groundwater flow system, 1; Influences on the groundwater flow by denudation of low permeability layer correlated with sea level change

Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo; Ichikawa, Yasuo*; Nakamura, Masaru*; Tomimori, Satoshi*

no journal, , 

no abstracts in English

Oral presentation

Alpha-decay spectroscopy of Rf and Lr isotopes

Asai, Masato; Haba, Hiromitsu*; Tsukada, Kazuaki; Sato, Nozomi; Kasamatsu, Yoshitaka*; Kaji, Daiya*; Morimoto, Koji*; Morita, Kosuke*; Sato, Tetsuya; Toyoshima, Atsushi; et al.

no journal, , 

Alpha-decay spectroscopy of odd-mass Rf and Lr isotopes was performed to establish proton and neutron single-particle orbitals. $$gamma$$ rays following the $$alpha$$ decay of $$^{259}$$Rf were observed for the first time through the $$alpha$$-$$gamma$$ coincidence measurement, and the neutron configuration of the ground state of $$^{259}$$Rf was assigned. It was found that the ground-state configuration of $$^{259}$$Rf is different from those of the lighter N = 155 isotones $$^{255}$$Fm and $$^{253}$$Cf. For the Lr isotopes, the proton configurations of the ground and isomeric states in $$^{255}$$Lr and the ground states of $$^{257}$$Lr and $$^{259}$$Lr were definitely identified through the high-resolution $$alpha$$ fine structure spectroscopy. Theoretical calculations based on the macroscopic-microscopic model revealed that the change of the ground-state configuration in the N = 155 isotones is strongly associated with the rapidly decreasing hexadecapole deformation with increasing atomic number.

Oral presentation

$$alpha$$-$$gamma$$ and high-resolution $$alpha$$ fine-structure spectroscopy for the heaviest nuclei

Asai, Masato; Haba, Hiromitsu*; Tsukada, Kazuaki; Sato, Nozomi; Kasamatsu, Yoshitaka*; Kaji, D.*; Morimoto, Koji*; Morita, Kosuke*; Sato, Tetsuya; Toyoshima, Atsushi; et al.

no journal, , 

Alpha-gamma and high-resolution $$alpha$$ fine-structure spectroscopy of Rf and Lr isotopes was performed to clarify the nuclear structure of superheavy nuclei. $$gamma$$ rays following the $$alpha$$ decay of $$^{259}$$Rf were observed for the first time through the $$alpha$$-$$gamma$$ coincidence measurement, and the neutron configuration of the ground state of $$^{259}$$Rf was assigned. It was found that the ground-state configuration of $$^{259}$$Rf is different from those of the lighter N = 155 isotones $$^{255}$$Fm and $$^{253}$$Cf. For the Lr isotopes, the proton configurations of the ground and isomeric states in $$^{255}$$Lr and the ground states of $$^{257}$$Lr and $$^{259}$$Lr were definitely identified through the high-resolution $$alpha$$ fine structure spectroscopy. Theoretical calculations based on the macroscopic-microscopic model revealed that the change of the ground-state configuration in the N = 155 isotones is strongly associated with the rapidly decreasing hexadecapole deformation with increasing atomic number.

Oral presentation

Hydrochemical analyses to evaluate groundwater system in Horonobe Area, Hokkaido, Japan

Sakai, Ryutaro; Munakata, Masahiro; Seguchi, Mariko*; Ooka, Masao*; Ichikawa, Yasuo*; Nakamura, Masaru*; Ishibashi, Junichiro*

no journal, , 

In the safety assessment for a geological disposal of radioactive waste, it is important to establish validation methods for deep groundwater flow system to estimate radionuclide migration to human environment through groundwater flow. This study discussed the method which estimates groundwater mixing condition and groundwater flow process using principal component analysis to groundwater chemistry and isotopic compositions in case of Horonobe area. The results demonstrated that there are three component of deep groundwater which has long residence time and surface water derived from meteoric water in this area.

Oral presentation

Fission of proton-rich nuclei

Nishio, Katsuhisa; Andreyev, A. N.*; Elseviers, J.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; et al.

no journal, , 

no abstracts in English

14 (Records 1-14 displayed on this page)
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