Neutron-capture γ-ray activation analysis was investigated using a 300 mCi Am−Be neutron source. Prominent photopeaks available
for the analysis were observed in several high-sensitivity elements, e.g. 0.477 MeV for boron, 0.336 MeV for samarium, 0.559
for cadmium, 0.230 MeV for cobalt, 0.370 MeV for mercury, and 0.518 MeV and 0.792 MeV for chlorine. As a practical application
of the method, determinations of the chlorine contents of various organic compounds were carried out, and it is shown that
Cl contents of 5–50 w/v% can be determined in this way with an experimental error of less than 5%.
Authors:T. Tsuji, Y. Yamamura, H. Watanabe, K. Saito, and M. Sorai
The heat capacities and magnetic susceptibilities of powdered samples of FexNbS2 (x=0.14, 0.21 and 0.30) were measured at temperatures from 8 to 303 K and from 5 to 300 K, respectively. For Fe0.14NbS2, the magnetic susceptibility exhibited an anomaly as a shoulder at about 57 K, but no heat capacity anomaly was observed at this temperature, indicating the appearance of a spin-glass state. Anomalies in the heat capacity for FexNbS2 (x=0.21 and 0.30) occurred at 100.5 and 45.0 K, respectively, where the magnetic susceptibility displayed a maximum, corresponding to an antiferro-paramagnetic phase transition. The electronic state of the iron atom is discussed on the basis of entropy analysis.
Authors:Y. Sakuma, Y. Ogata, N. Tsuji, H. Yamanishi, and T. Iida
Liquid scintillation counting is the most popular method for tritium measurement, however, it takes much time and a lot of doing to distill off the impurities before mixing the sample water and liquid scintillation cocktail. We have investigated the possibility of an alternative method to the distillation. We have found out that the filtration can be an alternative to distillation for the environmental water samples before electrolytic enrichment.
Authors:H. Yoshino, K. Murata, Y. Yamamura, T. Tsuji, H. Nishikawa, K. Kikuchi, and I. Ikemoto
The effect of thermal treatment on the electrical conductivity was studied for a quasi-one-dimensional organic conductor,
(DIMET)2I3 (DIMET=dimethyl(ethylenedithio)tetrathiafulvalene). After heating the samples up to a temperature between 340 and 370 K,
the electric resistivity was measured at low temperature down to 2 K and under pressure up to 1.6 Gpa. (DIMET)2I3 shows irreversible decrease in the electric resistivity between 350 and 356 K on heating. It was found that the heating above
350 K suppresses the spin-density-wave transition at 40 K and another metal-insulator transition appears at 18 K.
Authors:K. Shinotsuka, H. Yamanishi, Y. Sakuma, M. Tanaka, N. Tsuji, and T. Uda
n this study, the application for monitoring atmospheric tritium at the site of nuclear fusion facility is presented. Construction and examination of the tritium sampler and its arrangement at the site are mainly discussed. Atmospheric tritium concentrations at Toki site were determined in the sampling period from September 2000 to June 2001. Although the data for HTO were low because of their low specific activity (0.62 Bq/l), our average HT and CH3T data were 9.1 and 3.3 mBq/m3, respectively, and systematically lower than the previously reported values at the same site, even if the considerable decay correction was carried out. Suitable monitoring points are discussed by considering the local meteorological features at the Toki site. Since the wind conditions at this site were governed by diurnal and nocturnal wind blowing to the contrary directions, it is concluded that the monitoring points should be placed at the site boundary of downwind direction of these winds. Considering that the expected levels of effluent tritium in the D-D experiment at the National Institute for Fusion Science are competitive with those in the environment, the detailed variations of the environmental tritium should be comprehended to detect minute amounts of the artificial tritium.
Authors:Y. Kusaka, H. Tsuji, Y. Tamari, T. Sagawa, S. Ohmori, S. Imai, and T. Ozaki
A new radiochemical group separation method using APDC reagent in the extraction procedure has been developed. The method
has been applied to the radiochemical separation for activated biological samples and also to the preconcentration technique
for sea water samples. The transition elements are extracted into chloroform phase from the pH 3.0 aqueous phase and only
manganese is subsequently extracted from the pH 7.0 aqueous phase. The validity of the method is demonstrated by analyzing
the NBS standard reference materials. In the specimens preconcentrated from the sea water samples adjusted pH to 5.5, vanadium,
manganese, copper and zinc can be determined.
Authors:T. Iyogi, S. Ueda, S. Hisamatsu, K. Kondo, H. Haruta, H. Katagiri, M. Kurabayashi, Y. Nakamura, and N. Tsuji
To obtain an average dose from 222Rn to the people in Aomori Prefecture where the first Japan"s nuclear fuel cycling facilities are now under construction, we surveyed 222Rn concentrations in 109 dwellings in the Prefecture from 1992 to 1996. The outdoor 222Rn concentrations were also measured in gardens of 15 dwellings. The 222Rn concentrations were measured with passive 222Rn detectors which used a polycarbonate film for counting a-ray and could separate concentrations of 222Rn from 220Rn. Counting efficiencies of the detectors were calibrated with a standard 222Rn chamber in the Environmental Measurement Laboratory in USA and in the National Radiological Protection Board in UK. Geometric means of 222Rn concentration were 13 and 4.4 Bq.m-3 in the dwellings and outdoor, respectively. These values were consistent to nationwide survey results in Japan. The 222Rn concentrations in the dwellings depended on their age. The concentrations were higher in recent dwellings than in older ones. The radiation dose from 222Rn was estimated, taking into account the occupancy factor for inside and outside of dwellings. The annual dose was 0.32 mSv.y-1, and 99% of the dose came from the exposure to 222Rn inside the dwelling.
Authors:T. Fujinaga, Y. Kusaka, M. Koyama, H. Tsuji, T. Mitsuji, S. Imai, J. Okuda, T. Takamatsu, and T. Ozaki
A method is described for the determination of trace metal ions, V, Al, Cu, Mo Zn, and U, in natural water samples by neutron
activation analysis, using organic coprecipitation as a preconcentration method. The preconcentration of trace elements was
accomplished by converting the dissolved trace metal ions into the oxine chelates atpH 5.2 and extraction of the chelates witho-phenylphenol which is a liquid above 56 °C and solidifies at room temperature. After cooling the extraction system, the fine
particles of the organic phase were collected on a millipore filter and the precipitate was air-dried in a clean environment.
The solid extract was wrapped up in a sheet of clean polyethylene and subjected to neutron irradiation in a reactor for less
than 10 min at a thermal flux of 2·1013 n·cm−2·sec−1. γ-Ray spectrometry by a coaxial Ge(Li) detector connected to a 1024-channel PHA was performed on the irradiated sample without
further chemical separation, and thus the ppb level concentration of the elements in natural water samples could be determined.
The fundamental study of the collection of the trace elements is also described.
Authors:Y. Kusaka, H. Tsuji, Y. Fujimoto, K. Ishida, Y. Fukui, T. Mamuro, T. Matsunami, A. Mizohata, and S. Hirai
This report is the results of the studies on NAA of groundwater samples with comparison between direct and evaporation methods,
and of the applications for the samples of alluvium plain composed with granitiform soils and of Neogene strata composed with
Authors:N. Ishioka, H. Matsuoka, S. Watanabe, A. Osa, M. Koizumi, T. Kume, S. Matsuhashi, T. Fujimura, A. Tsuji, H. Uchida, and T. Sekine
The positron emitters11C,13N and18F and their labeled compounds have been produced for studies on plants using a newly developed positron emitting tracer imaging
system. Although this system covers, at present, a limited area in a plant, the distribution of the positron emitter fed into
the plant can be visualized dynamically. Further development of positron-emitter-labeled compounds is expected to elucidate
the physiological function of plants in vivo.