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Abstract  

Scission shapes composed of two touching spheroids in asymmetric and symmetric fission modes have been deduced from static potential calculations with the experimental fragment total kinetic energy and excitation energies for a typical fragment pair of 103Nb and 130Sn in the proton-induced fission of 232Th. It was found that the fragment deformation of the heavy fragment 130Sn in the symmetric fission mode was extremely large compared with that in the asymmetric fission and those of the complementary fragment 103Nb. Such scission shapes also provide internal excitation energies of pair fragments in the two fission modes. The deduced total internal excitation energies of complementary fragments for the two fission modes are nearly the same as the excitation energy of the fissioning nucleus. The results suggest that the two fission modes are strongly characterized by the degrees of fragment deformation of the heavy fragments, not by the total internal excitation energies at scission.

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Abstract  

Data on fragment mass yields in spontaneous and thermal neutron induced fission of wide range of nuclides from light actinides through heavy actinides were analyzed and completely described as mass distribution parameters, based on the concept of multimodal fission. The evidence that supports the existence of multi-components in the mass distribution of fission fragments, bimodal asymmetric mode in light actinide fission, bimodal symmetric mode in heavy actinide fission, and the existence of the boundaries of fission asymmetry has been obtained.

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Abstract  

Chemical states of tritium existing in neutron-irradiated solid lithium compounds were analyzed using a radiometric method. Nearly 100% of tritium was found in the T+ state in LiOH, Li2O2 and Li3N, while the T state predominated in LiH, Li7Pb2 and Li2C2. Tritium incorporated in Li2O, Li2S, LiF, LiCl, LiBr and LiI was distributed over the T+, T and T0 states. In Li2O crystals, the distribution of tritium in the T+ state increased from 58% to 81% with increasing neutron fluence from 2.5×1016 cm–2 to 6.3×1017 cm–2.

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Abstract  

An attempt was made to see if there is any correlation between the trace element concentrations in the human blood serum and some specific disease. The serum samples of the patients suffering from cancer, Down syndrome, and Banti syndrome were analyzed by the neutron activation method and compared with the trace element concentrations observed among the clinically healthy men. The cancer patients gave below normal concentrations in Rb, Mn, Fe, Co, Cu, Zn, Al and Se. The Down syndrome patients were found to have similar deficiencies in Cr, Mn, Fe, Co, Zn, Cu and Sb.

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Abstract  

Anion-exchange behavior of the group-5 elements, Nb and Ta, and their pseudo homologue Pa in HF and HF/HNO3 solutions was investigated by a batch method to find suitable conditions for the anion-exchange experiment of element 105 (Dubnium, Db). We determined the distribution coefficients of those elements on the anion-exchange resin as a function of the F and NO3 concentrations. Clearly different anion-exchange behavior was observed among these elements. Based on the results, we discuss the fluoro-complex formation of each element and suggest experimental conditions for the study of fluoride complexation of Db.

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Abstract  

The primary fragment mass-yield distribution for the asymmetric fission path in heavy nuclei, 233Pa, 239Np, 245Am and 249Bk at the excitation energy of ~20 MeV are experimentally constructed based on the intensities of total kinetic energies for individual mass splits. The results revealed an interesting phenomenon: in all the studied fissioning systems, the inner wings of the mass-yield distributions in the asymmetric fission path appear along the same mass-wall of A = 130 fragment mass. The asymmetric mass-yield distribution indicates the strong effect of structural shells in fragments on the final mass division process of the asymmetric fission path.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Mitsuoka, H. Ikezoe, T. Ikuta, S. Hamada, Y. Nagame, K. Tsukada, I. Nishinaka, and T. Ohtsuki

Abstract  

In order to separate rare fusion evaporation residues from the primary beam in flight, a recoil mass separator has been constructed at the JAERI tandem-booster facility. By using the recoil mass separator, new neutron-deficient isotopes209Th and212Pa have been produced. After a brief facility description, some recent experimental results are presented.

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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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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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