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Journal of Radioanalytical and Nuclear Chemistry
Authors: Sk. Latif, Y. Oura, M. Ebihara, G. Kallemeyn, H. Nakahara, C. Yonezawa, T. Matsue, and H. Sawahata

Abstract  

Neutron-induced prompt gamma-ray analysis (PGA) was applied to seven meteorite samples (Allende, Zagami, Acfer 209, ALH77005, ALH84001, EET79001 and Neagari). Samples were irradiated in both the thermal neutron and the cold neutron guided beams of JRR-3M at JAERI. Multiple samples of an Allende standard powder were analyzed for Si using two different methods: (1) the comparison method, using a Si standard, and (2) the mono-standard method, using Fe as an internal reference element. The Si concentrations determined by these two methods are in good agreement with literature values. The analytical sensitivity for Si using the cold neutron guided beam is∼14.3× higher than that for the thermal neutron guided beam. Other elements determined (B, Ca, Ti and S) also showed higher sensitivities using the cold neutron beam. The other meteorites studied showed some anomalous B and S values likely due to the effects of terrestrial weathering/contamination.

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Abstract  

Chemical compositions of suspended particulate matter (SPM) in atmosphere collected at Hachioji and Sakata in Japan from 2002 to 2004 were determined by prompt gamma-ray analysis and instrumental neutron activation analysis. About 40 elemental concentrations in SPM could be determined, and enrichment factors and elemental correlations were examined. Several elements such as Cl, Cr, Ag, Sb, and W were largely different between Hachioji and Sakata, although their sources are not clear at present.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: H. Nakahara, Y. Oura, K. Sueki, M. Ebihara, W. Sato, Sk. Latif, T. Tomizawa, S. Enomoto, C. Yonezawa, and Y. Ito

Abstract  

An internal monostandard method for PGAA is proposed for completely non-destructive analysis of elements in bulky samples by the use of a neutron beam guided out from the reactor. The method is essentially the same as the k 0 method except that it corrects for the change of relative -ray counting efficiencies caused by the absorption and scattering of neutrons and absorption of -rays within the sample. Some examples of applications to archaeological samples of earthen wares, bronze mirrors, and to voluminous meteorite samples are demonstrated, and its future application to the in-situ studies of distribution and metabolism of a certain elements in animals is also explained.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: J. Moon, M. Ebihara, B. Ni, B. Arporn, P. Setyo, R. Theresia, B. Wee, N. Salim, and P. Pabroa

Since 2000, collaborative studies for applying NAA have been performed through the Forum for Nuclear Cooperation in Asia (FNCA) sponsored by the Japanese Government. White rice is a main food for Asians and thus was selected as a common target sample for a collaborative study in 2008. Seven Asian countries including China, Indonesia, Japan, Korea, Malaysia, Philippines and Thailand, are greatly concerned about the composition of arsenic, heavy metals, and essential trace elements and took part in this study. Rice samples were purchased and prepared by following a protocol that had been proposed for this study. Samples were analyzed by their own NAA systems. In each country, more than 10 elements were examined and the results were compared. These data will be very useful in the monitoring of the levels of food contamination and to evaluate the nutritional status for people living in Asia.

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Journal of Radioanalytical and Nuclear Chemistry
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

Abstract  

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.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Ebihara, Y. Chung, H. Dung, J. Moon, B. Ni, T. Otoshi, Y. Oura, F. Santos, F. Sasajima, Sutisna, B. Wee, W. Wimolwattanapun, and A. Wood

Abstract  

Air particulate matter (APM) samples (PM2.5 and PM10–2.5) were collected at 13 sampling points in 8 Asian countries and their chemical compositions were determined by using neutron activation analysis (NAA) with the k 0-standardization method in addition to conventional comparative method of NAA. Analytical data showed that mass concentration and elemental composition of the APM collected are variable in terms of time and space, and are related to the characteristics of the sampling sites concerned. NAA was proved to be highly effective for the regional characterization of APM in chemical composition.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Ebihara, Y. S. Chung, W. Chueinta, B.-F. Ni, T. Otoshi, Y. Oura, F. L. Santos, F. Sasajima, Sutisna, and A. K. B. H. Wood

Summary  

Seven Asian countries have been collaborating in collecting airborne particulate matter (APM) in their individual countries and analyzing them by neutron activation analysis as a common analytical tool. APM samples were collected into two fractions of fine and coarse grains (PM2 and PM2-10, respectively). Analytical data were compared from several viewpoints such as particulate sizes, locality of sampling sites (either urban or rural) and geographical location of participating countries. Chemical composition and their monthly variations as well as mass concentrations appear to be highly characteristic for individual sampling sites, suggesting that NAA data are suitable for evaluating the air quality in each site.

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