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Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Akiyama, H. Haba, K. Tsukada, M. Asai, A. Toyoshima, K. Sueki, Y. Nagame, and M. Katada

Abstract  

The properties of a metallofullerene that encapsulates 225Ac were studied by radio-chromatographic methods. The results of chromatography on a Buckyclutcher column suggest that there are some metallofullerene isomers of AcC82. The identical HPLC retention time of the major AcC82 peak with that of La@C82 indicates that the structure of one of the AcC82 isomers is the same as La@C82.

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Abstract  

Adsorption of carrier-free radiotracers 181W and 93mMo produced in the 181Ta(p, n) and natNb(p, n) reactions, respectively, on anion-exchange resin was studied in mixed solution of HF and HNO3 in a concentration range of 10−4–10−1 M HF/0.1 M HNO3. Distribution coefficients (K d) of 181W and 93mMo at 70 °C showed the V-shaped variation with the minimum at around 10−1 M HF/0.1 M HNO3, although variation of the K d values for 93mMo was quite small compared with that for 181W. Formation of oxofluoro complexes for W and Mo is briefly discussed.

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Abstract  

An isothermal chromatographic apparatus was developed for the on-line experiments of super heavy elements in gas phase. As a model of Rf, we investigated the gas phase chemistry of Zr and Hf chlorides. The dependence of the reaction efficiency on temperature was examined. It was found that about 80% of Zr and Hf reacted with chlorinating gas at 900 °C. Adsorption enthalpies of Zr and Hf chlorides were deduced from the isothermal chromatograph by the Monte Carlo simulation based on the microscopic model proposed by Zvára.

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Abstract  

99Ru and57Fe-Mössbauer spectroscopic and magnetization measurements were made in order to clarify the magnetic properties of a Huesler alloy, RuFe2Si. The result obtained from99Ru-Mössbauer spectrum leads to the conclusion that Ru atoms were substituted by both Fe[A, C] and Fe[B], but the latter preferentially.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Akiyama, K. Sueki, H. Haba, K. Tsukada, M. Asai, T. Yaita, Y. Nagame, K. Kikuchi, M. Katada, and H. Nakahara

Abstract  

We have, previously, reported on the HPLC elution behavior of the Th, Pa, U, Np, and Am metallofullerenes and the UV/vis/NIR absorption spectra of the Th@C84 and U@C82 species. In this paper, the followings are reported: (1) Pu metallofullerenes were produced and their HPLC elution behavior was investigated using a radiotracer technique. The HPLC chromatogram of this metallofullerene was found to be almost the same as that of the Np and Am metallofullerenes. (2) The oxidation states of Th@C84 and U@C82 produced in macroscopic quantities were examined by XANES (X-ray absorption near edge structure) measurements. The oxidation state of the U atom in the C82 fullerene cage was estimated to be 3+ with the formal charge of the ionic molecule being U3+@C82 3-.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: T. Maruyama, D. Kaji, T. Kaneko, S. Goto, K. Tsukada, H. Haba, M. Asai, S. Ichikawa, Y. Nagame, and H. Kudo

Abstract  

Rapid chemical separation of berkelium is essential in order to measure the unknown isotope 252Bk. An anion exchange system of mineral acid and methanol was examined. An elution curve of Bk was obtained using 250Bk produced by the 248Cm+18O system and the 251Bk activity could be measured in the preliminary experiments. The whole chemical separation was completed within 30 minutes.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: A. Toyoshima, K. Tsukada, H. Haba, M. Asai, S. Goto, K. Akiyama, I. Nishinaka, S. Ichikawa, Y. Nagame, and A. Shinohara

Abstract  

The anion exchange behavior of 255No produced by the 248Cm(12C,5n) reaction has been investigated in 11.5M HCl, 4M HCl and 8M HNO3 to deduce the behavior of 'primordial 257No' produced via 248Cm(18O,5n)261Rf 257No before anion exchange separation in the 261Rf experiment. It was found that 255No is mostly eluted from the anion exchange column with these solutions. The contribution of 'primordial 257No' to the -decay events of 261Rf in the 261Rf experiment was evaluated based on the present results.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: T. Sekine, S. Ichikawa, A. Osa, M. Koizumi, H. Iimura, K. Tsukada, I. Nishinaka, Y. Hatsukawa, Y. Nagame, M. Asai, Y. Kojima, T. Hirose, M. Shibata, H. Yamamoto, and K. Kawade

Abstract  

Studies on the decay of unstable nuclei using the two on-line isotope separators of JAERI are reviewed for the past five years. With the previously established ion-source technique using mono-oxide ion formation in a thermal ion source, the new nuclides125Pr and127Pr have been identified in heavy-ion fusion residues. Further, with a newly developed gas-jet coupled thermal ion source, the new nuclides166Tb,165Gd,161Sm and236Am have been identified by bombarding238U and235U targets with a proton or6Li beam. Other studies, including off-line experiments, by decay spectroscopy, laser spectroscopy and Mössbauer spectroscopy are described.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Goto, D. Kaji, I. Nishinaka, Y. Nagame, S. Ichikawa, K. Tsukada, M. Asai, H. Haba, S. Mitsuoka, K. Nishio, M. Sakama, Y. Zhao, K. Sueki, K. Tanikawa, K. Takamiya, H. Kudo, and H. Nakahara

Abstract  

To study the correlation between fragment mass distributions and shell structures of fission fragments, fragment mass and energy distributions in proton-induced fission of 232Th and uranium isotopes, 233,235,238U, were precisely measured using a double-TOF method. It was found that the lighter side of the heavier wing of asymmetric mass distributions shifts to larger fragment mass number corresponding to the N/Z value of the fissioning nucleus. The results are explained qualitatively by the change of the most probable mass number of fission fragments of Z = 50 proton-shell.

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