Authors:K. Sakamoto, N. Aota, Y. Miyamoto, S. Kosanda, Y. Oura, T. Okui, M. Igarashi, and T. Nakanishi
Fifteen GSJ (Geological Survey of Japan) and six KIER (Korean Institute of Energy and Resources; now Korean Institute of Geology, Mining and Materials, KIGAM) igneous rock series and nine GSJ sedimentary rock series reference samples were analysed for 21–29 elements by neutron and/or photon activation analysis (NAA and PAA); 14 MeV-NAA for Si and Al, fission track method for U, radiochemical and instrumental NAA for rare earth elements, with reactor neutrons for the latter two. Instrumental neutron and photon AA for the remaining elements were performed with reactor neutrons and bremsstrahlung of end-point energy of 30 MeV, respectively. The reactor irradiations were performed at core sites and also a thermal column of the Kyoto University Research Reactor. All of the radioassays were performed by -ray spectrometry with HPGe-detectors. The present results from the different types of irradiation are compared and discussed in terms of elemental abundances and rock types.
Authors:H. Haba, H. Matsumura, Y. Miyamoto, K. Sakamoto, Y. Oura, S. Shibata, M. Furukawa, and I. Fujiwara
The recoil properties of 26 radionuclides produced in the photonuclear reactions on Cu at bremsstrahlung end-point energies
(E0) of 250 to 1000 MeV have been investigated using the thick-target thick-catcher method. Kinematic properties of the product
nuclei were calculated by the two-step vector velocity model. The calculated mean kinetic energies,T, of product nuclei increase with increase of the mass difference between products and target, reflecting the resonance natures
and absorption mechanisms. TheT atE0≥600 MeV were well reproduced by a calculation performed by PICA code byGabriel andAlsmiller atE0=400 MeV, except for (γ,xn) products by giant-resonance.
Authors:Y. Oura, H. Iguchi, T. Nagahata, H. Nakamatsu, T. Otoshi, and M. Ebihara
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.
Authors:M. Ebihara, Y. Oura, T. Ishii, M. Setoguchi, H. Nakahara, and T. Ohtsuki
Chondritic meteorite samples were analyzed nondestructively by photon activation analysis. Powdered samples weighing about 50 mg each were irradiated with photons (-rays) converted from electrons accelerated by a linear electron accelerator at 20 and 30 MeV. With 30-minute and 6-hour irradiations, 11 and 12 elements with duplication of 6 elements could be determined, respectively. Considering that several major elements including Mg, Si and Fe can be determined in addition to Ti, Rb, Sr, Y and Zr, which cannot or hardly be determined by instrumental neutron activation analysis (INAA) with rather high sensitivity, instrumental photon activation analysis is as effective as INAA.
Authors:Sk. Latif, Y. Oura, M. Ebihara, G. Kallemeyn, H. Nakahara, C. Yonezawa, T. Matsue, and H. Sawahata
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.
Authors:H. Nakahara, Y. Oura, K. Sueki, M. Ebihara, W. Sato, Sk. Latif, T. Tomizawa, S. Enomoto, C. Yonezawa, and Y. Ito
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 k0 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.
Authors:Y. Zhao, T. Ohtsuki, Y. Nishinaka, K. Tsukada, S. Ichikawa, H. Ikezoe, Y. Hatuskawa, K. Hata, M. Tanikawa, Z. Qin, K. Sueki, Y. Oura, H. Kudo, and H. Nakahara
Two kinds of scission configurations for certain mass division have been verified by the accurate measurements of fragment
velocities in protoninduced fission of actinides: compact and elongated scission configurations. A correlation between the
binary scission configurations and mass yield distributions reveals that elongated scission configurations are associated
with the symmetric mass distribution and compact scission configurations with the asymmetric mass distribution. The elongation
properties of nuclei at scission in a wide range of actinides fissions are studied. The results suggest that the compact and
the elongated scission configurations in light actinides fission smoothly change to the scission properties of the symmetric
and the asymmetic modes in heavy actinides fission.
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.
Authors:Y. Oura, A. Saito, K. Sueki, H. Nakahara, T. Tomizawa, T. Nishikawa, C. Yonezawa, H. Matsue, and H. Sawahata
Prompt γ-ray analysis using the internal monostandard method was applied to voluminous archaeological bronze mirrors produced
in ancient China. Sn/Cu content ratios were determined nondestructively by this method. Furthermore, Au/Cu, As/Cu, and Sb/Cu
content ratios were determined by means of measuring decay γ-rays emitted from radioactive nuclides produced within samples
via (n,γ) reactions. It is clear that the Sn/Cu content ratios in bronze mirrors produced in the Sung era is smaller than
in ones produced in between the Han and the Tung era.
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
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.