A nondestructive photon activation procedure with 30 MeV bremsstrahlung followed by high-resolution gamma-spectrometry has
been applied to the multielement determination in tobacco leaves and commercial cigarettes. The elements determined by this
method included essential minor elements such as Ca, Cl, K and Mg, essential trace elements such as Fe, Mn and Zn, and possibly
toxic elements such As and Sb. The NBS Orchard Leaves could successfully be used as a comparative standard. The method is
quite simple and gives good reproducible results for at least 12 elements.
207Bi and other fallout nuclides /137Cs and60Co/ in sea sediments were measured, and other quantities were plotted against ignition losses of the samples which were separately determined by gravimetry. For each nuclide radioactivity was closely correlated to the ignition loss of the sample. A similar relation was nearly hold good for the amount of stable lead and the quantity of organic carbon. From the results a probable mechanism of sedimentation is suggested.
On a appliqué l'activation aux photons à l'analyse non-destructive de roches étalons USGS. 16 éléments sont dosés. On a irradié
simultanément l'échantillon de roche et les étalons multiéléments dans un bremsstrahlung de 30 MeV, et on a mesuré l'activité
des adioisotopes produits par les réactions (λ,n)et (λ,p) avec un détecteur Ge(Li). La validité de la méthode est démontrée
par les résultats obtenus pour ces roches. Les résultats concernent les éléments suivants: Na, Mg, Ca, Ti, Cr, Mn, Fe, Co,
Ni, Rb, Sr, Y, Zr, Nb, Ba et Ce.
Authors:T. Kato, K. Masumoto, N. Sato, and N. Suzuki
A comprehensive study on the yields of photonuclear reactions of various types has been performed, and sensitivities and the
effects of interferences in multielement photon-activation analysis have been evaluated by bremsstrahlung activation of many
elements with maximum energies ranging from 30 to 60 MeV. The applicability and reliability of the method were demonstrated
by analyzing standard round-robin samples and then by presenting the elemental abundances in several geological, biological
and environmental materials. The method was almost insensitive to matrix effects and was assessed to be promising for nondestructive
multielement determination of the materials of wide variety, giving good reproducible results for 20 or more elements.
Authors:X. Liang, K. Tsukada, A. Toyoshima, Z. Li, M. Asai, T. Sato, N. Sato, and Y. Nagame
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 (Kd) 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 Kd values for 93mMo was quite small compared with that for 181W. Formation of oxofluoro complexes for W and Mo is briefly discussed.
Authors:R. Amano, Y. Shiokawa, N. Sato, and Y. Suzuki
Preparation of lanthanide fluoride and chloride films has been studied by chemical vapor deposition (CVD) using Ln(thd)3 (Ln=lanthanide(III); thd=2,2,6,6-tetramethyl-3,5-heptanedionato ligand) and Y(thd)3 with gas mixture systems of CF2Cl2 (difluorodichloromethane)/O2 and CF2Cl2/H2. Two kinds of fluorides, LnOF oxyfluoride and LnF3 triffluoride, were obtained separately along a CVD tube at atmospheric pressure and temperature as low as 300–600°C by the reaction of Ln(thd)3 chelates with CF2Cl2/O2 gas system. The chemical characteristics of the CVD products were considered from the thermochemical point of view.
Authors:T. Hashimoto, K. Sato, Y. Yoneyama, and N. Fukuyama
Some improvements of the detection sensitivity in pulse time interval analysis (TIA) based on selective extraction of successively - correlated decay events within millisecond order from random or background events, were established by the utilization of PSD, to reject /-pulses from -ones and a simple chemical procedure of radium separation, together with the use of well resolved scintillator. By applying the PSD, the contribution of -decay events was completely eliminated in both the -spectra and the TIA distribution curves as well as the improvement into clear energy resolution and the enhancement of detection sensitivity for the TIA. As a result, the TIA and -spectrometric analysis of226Ra-extract showed the existence of223Ra (Ac-series) and /-correlated events with correlated life (due to 0.16 ms due to214Bi()
214Po()) along with a singly well resolved -peak to be useful for the determination of226Ra (U-series). The difference of half-lives (145 and 1.78 ms) due to216Po and215Po (direct daughters of224Ra for Th-series and223Ra for Ac-series, respectively) was also proven for the possibility of the simultaneous determination of both correlated events by using the TIA/PSD combined with chemical separation and liquid scintillation counting method. Finally, the simultaneous determination of three natural decay series, which include U-, Th- and Ac-series nuclides, have been conveniently carried out for some environmental samples using the present method combined with225Ra yield tracer (Np-series).
Authors:Y. Ishikawa, N. Sato, E. Nakamura, T. Sekine, and K. Yoshihara
Accumulation of radiosilver108mAg and110mAg in oysters (Crassostrea gigas) and their behavior in marine environments has been studied in the northeast Pacific coast in Japan. Enrichment of radiosilver in oysters depends on topographical conditions; significant bioaccumulation occurred in open bays, while it was hardly observed in bays with narrow shaped entrances. From these observations difference of the behavior of radiosilver between open and nearly closed bays is suggested.110mAg in oysters decayed with an effective halflife of about 150 days for both the Chinese nuclear weapon test and the Chernobyl accident. In contrast to radiosilver, the fission product nuclide137Cs was almost independent of topographical conditions, and its concentration was constant.110mAg bioaccumulation in oysters after the Chernobyl accident in 1986 was found in both open and nearly closed bays, the latter showing much lower concentration of radiosilver than the former. Specific activity of108mAg in oysters was determined in bays open to the Pacific Oceans.
Authors:N. Yanase, H. Isobe, T. Sato, Y. Sanada, T. Matsunaga, and H. Amano
Surface soil samples (0–1 cm) were collected to understand the role of hot particle (HP) in migration of radionuclide approximately 11 years after the Chernobyl accident. Three types of HPs were found by the analyses using alpha-track technique and scanning electron microscopy/energy dispersive X-ray spectrometer (SEM/EDX). The dissolution of HPs has been affected by the existing type of HPs. Six-stage sequential selective extraction procedure was carried out to define the chemical forms of uranium, 241Am and 137Cs. The chemical form of radionuclides in surface soil is significantly different between the west and the north traces of radioactive plumes approximately 11 years after the accident.
Authors:H. Hasegawa, N. Akata, H. Kawabata, Y. Chikuchi, T. Sato, K. Kondo, and J. Inaba
7Be deposition fluxes and atmospheric concentrations were measured at Rokkasho Village, Aomori Prefecture, Japan, from 2000
to 2005. It was confirmed that the 7Be deposition fluxes were minimum in summer, and the fallout maximizes in winter. The atmospheric concentration of 7Be was especially low in summer, and high in the other three seasons. A positive correlation was observed between the amount
of precipitation and 7Be deposition. Clear seasonal differences were evident among the ratios of 7Be deposition flux to precipitation amounts in the four seasons. The ratios were especially high in winter, higher than those
in the other three seasons. 7Be deposition flux was estimated by a simple simulation model using atmospheric 7Be concentrations and local meteorological data. As a result, the estimated deposition value was relatively lower than the
measured value in winter.