Production and separation of astatine isotopes in the Li + Pb reaction

Nishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Maeda, Eita*; Watanabe, Shigeki; Hashimoto, Kazuyuki; Ishioka, Noriko; Makii, Hiroyuki; Toyoshima, Atsushi; Yamada, Norihiro*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 304(3), p.1077 - 1083, 2015/06

https://doi.org/10.1007/s10967-015-3975-y

Production cross sections of astatine isotopes At in the 29-57 MeV Li induced reaction with Pb target have been measured by - and -ray spectrometry. Excitation functions of production cross sections have been compared with a statistical model calculation to study the reaction mechanism of Li + Pb. Considerably small experimental cross sections of At and At compared with the calculation were clearly observed at incident energies higher than 44 MeV, indicating that the effects of breakup reaction play a role. A chemical separation of astatine from an irradiated lead target has been studied with a dry-distillation method. A complementary way to produce astatine isotopes has been developed.

Sorption of Eu(III) on granite; EPMA, LA-ICP-MS, batch and modeling studies

Fukushi, Keisuke*; Hasegawa, Yusuke*; Maeda, Koshi*; Aoi, Yusuke*; Tamura, Akihiro*; Arai, Shoji*; Yamamoto, Yuhei*; Aosai, Daisuke*; Mizuno, Takashi

Environmental Science & Technology, 47(22), p.12811 - 12818, 2013/11

https://doi.org/10.1021/es402676n

Eu(III) sorption on granite was examined by the combined microscopic and macroscopic approaches. Polished thin sections of the granite were reacted with solutions containing 10 M of Eu(III) and analyzed using EPMA and LA-ICP-MS. The Eu enrichment up to 6 wt.% was observed on most of the biotite grains. The Eu-enriched parts commonly lose K, which is the interlayer cation of biotite, indicating that the sorption mode is cation exchange in the interlayer. Batch Eu(III) sorption experiments on granite and biotite powders were conducted. The macroscopic sorption behavior of biotite was consistent with that of granite. The obtained sorption edges can be reproduced reasonably by the modeling considering single-site cation exchange reactions. Granite is complex mineral assemblages. However, the combined microscopic and macroscopic approaches revealed that elementary reactions by single phase can be representative for the bulk sorption reaction in complex mineral assemblages.

The Effect of temperature, pressure, and sulfur content on viscosity of the Fe-FeS melt

Terasaki, Hidenori*; Kato, Takumi*; Urakawa, Satoru*; Funakoshi, Kenichi*; Suzuki, Akio*; Okada, Taku; Maeda, Makoto*; Sato, Jin*; Kubo, Tomoaki*; Kasai, Shizu*

Earth and Planetary Science Letters, 190(1-2), p.93 - 101, 2001/07

https://doi.org/10.1016/S0012-821X(01)00374-0

The Fe-FeS melt is thought to be the major candidate of the outer core material. Its viscosity is one of the most important physical properties to study the dynamics of the convection in the outer core. We performed the in situ viscosity measurement of the Fe-FeS melt under high pressure using X-ray radiography falling sphere method with a novel sample assembly. Viscosity was measures in the temperature, pressure, and compositional conditions of 1233-1923 K, 1.5-6.9 GPa, and Fe-Fe S (wt %), respectively. The viscosity coefficients obtained by 17 measurements change systematically in the range of 0.008-0.036 Pa s. An activation energy of the viscous flow, 30 kJ/mol, and the activation volume, 1.5 cm /mol, are determined as the temperature and pressure dependence, and the viscosity of the Fe S melt is found to be smaller than that of the Fe melt by 15 %. These tendencies can be well correlated with the structural variation of the Fe-FeS melt.

Development of in-situ sorption experiment system in underground research laboratory

Hasegawa, Yusuke*; Yamamoto, Yuhei; Aosai, Daisuke; Mizuno, Takashi; Maeda, Koshi*; Fukushi, Keisuke*

no journal, , 

no abstracts in English

Determination of the partition coefficient (Kd) under in-situ groundwater conditions using a hydrochemical monitoring system

Yamamoto, Yuhei; Aosai, Daisuke; Mizuno, Takashi; Fukushi, Keisuke*; Hasegawa, Yusuke*; Maeda, Koshi*

no journal, , 

no abstracts in English

Identification and characterization of phase governing Eu(III) uptake in granite by microscopic observations

Hasegawa, Yusuke*; Fukushi, Keisuke*; Maeda, Koshi*; Yamamoto, Yuhei; Aosai, Daisuke; Mizuno, Takashi

no journal, , 

Modeling and batch experiment for understanding of Eu(III) sorption on granite

Maeda, Koshi*; Fukushi, Keisuke*; Hasegawa, Yusuke*; Yamamoto, Yuhei; Aosai, Daisuke; Mizuno, Takashi

no journal, , 

http://www2.jpgu.org/meeting/2012/html5/PDF/U-04/U04-16.pdf

no abstracts in English

Nuclear and radiochemical study of production and utilization of radioactive astatine isotopes in the Li + Pb reaction

Nishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Yamada, Norihiro*; Makii, Hiroyuki; Watanabe, Shigeki; Ishioka, Noriko; Hashimoto, Kazuyuki

no journal, , 

Production and utilization of radioactive astatine isotopes in the Li + Pb reaction

Nishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Yamada, Norihiro*; Makii, Hiroyuki; Toyoshima, Atsushi; Watanabe, Shigeki; Ishioka, Noriko; et al.

no journal, , 

Production cross sections of astatine in 29-57 MeV Li + Pb have been measured by - and -ray spectrometry. Excitation functions of production cross sections have been compared with a statistical model calculation to study the reaction mechanism of the Li + Pb reaction. It indicates that the breakup of Li plays a rule in the Li + Pb reaction. Besides, we have developed a dry-distillation method which separates carrier-free astatine from an irradiated lead target.

Production and utilization of astatine radioisotopes using Li ion beams

Nishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Taniguchi, Takumi*; Murakami, Kento*; Watanabe, Shigeki; Suzuki, Hiroyuki; Ishioka, Noriko; et al.

no journal, , 

In general, an -emitter At which is a prospective candidate for utilization in targeted alpha radiotherapy is produced through the Bi(He, 2n)At reaction. In contrast, our project is focusing on the production in the Bi(Li, 5n)Rn reaction. This enables us to supply At in a Rn/At generator system. The daughter At (7.2 h half-life) is extracted from the parent Rn (14h), expanding time-frame for transportation and use of At. To use astatine and iodine radioisotopes in our project, the excitation functions of Bi(Li, xn)Rn, Pb(Li, xn)At and Sn(Li, xn)I reactions have been measured. In addition to that, separation techniques have been developed. We report not only on the production and separation of astatine and iodine radioisotopes in the reactions but also on the utilization of those radioisotopes.