We conducted this study to analyze the correlation between 137Cs concentration of new shoots harvested in the first crop of tea in 2012, and new shoots harvested in the shuto-bancha in 2011 and old leaves harvested at the same time respectivily. In the first crop of tea in 2012, the 137Cs concentration of new shoots was related to that of old leaves, and the correlation of the coefficient was 0.663(p<0.01). The Ratio of 137Cs concentration(new shoots/old leaves) was related to the days until harvest of the first crop of tea in 2012, and the correlation coefficint was −0.771(p<0.01). This suggested that the decrease of the ratio of 137Cs concentration was derived from the dillution effect due to growth and development of tea plants. Regression analysis was performed to forecast the 137Cs concentration of the new shoots in the first crop of tea. The 137Cs concentration of new shoots in the harvested first crop of tea(Y) was related to the 137Cs concentration of old leaves harvested the previous winter(X). The correlation of the coefficient was 0.783(p<0.05), and the coefficient of determination was 0.558, and the regression fomula was Y=0.591X+28.035. Furthermore, the 137Cs concentration of new shoots of the first crop of tea in 2012 decreased about 1/6 to 1/25 compared with that of new shoots of the first crop of tea in 2011.
When evaluating an environmental γ-ray dose rates, it is important to determine the individual contributions of both natural and artificial radioactive nuclides to the overall measured rate. In areas where nuclear contamination is suspected, however, it can be difficult to rapidly ascertain these relative contributions. This paper describes the use of a portable NaI(T1) scintillation spectrometer to quickly and accurately measure γ-ray dose rates at 16 locations in Japan, in order to construct a contamination map on an emergency basis. The survey data showed that, in locations with differing energy distributions, there were noticeable correlations between the total γ-ray dose and the count rates within the specific energy ranges of 1400 — 3000, 1650 — 3000and 1800 — 3000keV, and these correlations differed markedly between natural and artificial nuclides. These observations suggested that the artificial nuclide contribution to the γ-ray dose rate could be calculated using the correlations, and subsequent analysis of the data confirmed that this was possible. The resulting estimates were accurate to within approximately 3.3, 0 and 10% within the energy ranges of 1400 — 3000, 1650 — 3000 and 1800 — 3000keV as the 30nGy/h, respectively.
In affected areas by the Fukushima nuclear accident, effects of three types of shields with thickness of 2mm on ambient equivalent dose rates were examined inside seven residents' houses aiming for dose reduction of residents. In these houses, the indoor incident γ-ray unfolded energy spectra were obtained. Estimated dose rates due to radiocaesium were devided into uncollided and scattered dose rates, and ratios of dose rates due to the latter to those due to the former, S/U were evaluated. In all types of shields, shielding effects increased as the ratios of S/U increased and 27% of ambient equivalent dose rate reduction at maximum was obtained, indicating the shield is very effective to attenuate scattered radiations. In affected areas, in particular, with low ambient equivalent dose rates, the application of shields to resident's house can be used reasonably and effectively for dose reduction of residents.
An acid extraction method, being one of volume reduction technologies on soils contaminated with radioactive caesium, was carried out in this paper to obtain its fundamental knowledge and to clarify its applicability to clay soil. Soil samples collected at nine months after the Fukushima Daiichi Nuclear Plant accident were extracted from acids under various conditions. Results showed that extraction efficiency for radioactive caesium ranged from 24 to 71% for nitric acid and was higher in sandy soil than in soil with high silt and clay ratio. Furthermore, about 50% of extraction efficiency was found in typical gray lowland soil of paddy field in Fukushima.
The multi-stable isotopic analysis method has employed to solve food authenticity problems. Stable isotope ratio of the light elements such as H, C, N, and O in food samples (e.g., rice, beef, and eel) were precisely analyzed by elemental analysis/isotope ratio mass spectrometry. Those samples were mainly taken from four different countries; Japan, United States of America, Australia, and China as comparison. All the rice samples were grown in the presence of either natural and or artificial fertilizer. The beef samples were taken from three different countries;Japan, United States of America, and Australia. Imported beef samples were also presented from the Ministry of Agriculture, Forestry and Fisheries, Japan, and compared with a correlation equation. The eel samples were taken from the three different countries and areas;Japan, China, and Taiwan. δX values showing some differences, all the Japanese food samples were clearly distinctive from the United States of America, Australia, China, and Taiwan samples. The results may be explained by the regional differences in isotope signatures of the climate, utilized nutrition, and/or quality of irrigation water among the farming countries. The statistical distinction could be one of the useful metrics to extract the food samples (rice, meat, fish, etc.) grown in Japan from those grown in the other countries. The dynamics analysis studies on stable isotopic behavior(i.e., Isotopomics) in human metabolism may be looking forward to establish a new science in near future.
Matrix isolation is a very useful technique to measure Mössbauer spectra of isolated atoms, molecules, and unstable species, and it provides information on their electronic structures. Photochemistry of organometallic compounds, such as Fe(acac)3 and Fe(CO)5, were studied. Matrix isolation technique was applied for measurements of unstable species produced by reactions of laser-evaporated iron atoms and various reactant gases. Shape of material may affect the chemical structures, and particles and thin films may have unique properties which are not obtainable in normal bulk solid materials. Mössbauer spectrometry provides direct information on composition and magnetic orientation of the iron based materials. Studies on iron films and iron based material films produced pulsed-laser deposition are demonstrated.
A series of articles on “Neutron Inelastic Scattering”, published in the following twelve months in 2013, will provide readers with information on dynamics of atomic and molecular motions in condensed matters covering a wide variety of research fields. This series complements a full coverage of major neutron utilization with two previously published series, “Neutron Imaging” and “Neutron Diffraction(elastic scattering)”.