Authors:S. Shibata, E. Kawano, K. Kimura, T. Mine, and M. Harada
14C dating of 6 Japan cedars having the relative growing ages were made. On the basis of correlation analysis of our data to
a14C age data set, INTCAL of CALIB (Stuiver), the growing ages of these Japan cedars were estimated (BC 1090-2375). The atmospheric14C concentration (Δ14C) at their growing ages were obtained from the14C age data. The variation of Δ14C shows basically the same pattern with that of Europe or America (r=0.783).
Authors:N. Momoshima, Y. Takashima, M. Koike, Y. Imaizumi, and T. Harada
A determination procedure has been developed for210Bi and210Po in environmental samples and was applied for pine needles. Bismuth-210 and210Po separated from the parent nuclide210Pb as BiOCl precipitate were extracted simultaneously by TOPO/toluene containing PPO and POPOP. The separation of210Bi and210Po from210Pb was almost satisfactory. The activity of210Bi+210Po in the TOPO/toluene was measured periodically by liquid scintillation counting for about 20 days after separation. The time course of the decreasing pattern of the activity was determined by the initial activity ratio210Po/210Bi. The decreasing pattern of the activity was compared with theoretical patterns, and best estimates for210Po and210Bi were obtained by non-linear least-squares fitting. The activities of210Bi and210Po were determined for one-year and two-year old pine needles fro the same pine tree, and weathering half-time and deposition rate of these nuclides was discussed.
Authors:M. Nogami, Y. Sugiyama, T. Kawasaki, M. Harada, Y. Morita, T. Kikuchi, and Y. Ikeda
Adsorptivity of polyvinylpolypyrrolidone (PVPP), a candidate resin with selectivity to U(VI) in HNO3 media, to various metal ions was examined. It was found that PVPP has a strong adsorptivity to U(VI) in wide concentration
range of HNO3. The Scatchard plot analysis revealed that the adsorption of U(VI) by PVPP occurs at plural binding sites. The infrared spectroscopic
analysis suggested that the strong binding site is due to the coordination of the carbonyl oxygen atom and the nitrogen atom
in the pyrrolidone ring to UO22+. It was also found that fission product ions except Re(VII) as the simulant of Tc(VII) and Pd(II) are not adsorbed onto PVPP.
The adsorptivities to Tc(VII) and Pd(II) species are weak, indicating that U(VI) can be separated from other metal ions by
Authors:Y. Hatsukawa, N. Shinohara, K. Hata, K. Kobayashi, S. Motoishi, M. Tanase, T. Katoh, S. Nakamura, and H. Harada
To determine the cross sections of the135Cs(n,γ)136Cs reaction, a sample of135Cs included in a “standardized solution” of137Cs was used as a target and irradiated in a reactor. The ratio of the atom number of135Cs to that of137Cs was determined to be 0.89±0.03 with a quadrupole mass spectrometer. The thermal cross section and the resonance integral
measured in this study were determined to be 8.3±0.3 and 38.1±2.6 b respectively.
Authors:Y. Oura, R. Watanabe, M. Ebihara, Y. Murakami, Y. Toh, A. Kimura, M. Koizumi, K. Furutaka, M. Oshima, K. Hara, T. Kin, S. Nakamura, and H. Harada
A prompt gamma-ray analysis system using multiple detection method (MPGA system) was constructed at the neutron guide hall
of the JRR-3M reactor of the Japan Atomic Energy Agency. We applied 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 gamma ray activation analysis (PGAA) at JRR-3M. 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. At the present
time, 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 installed at JRR-3M. It is expected that it will determine a lot of
trace elements after appropriate adjustments and modifications.