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Abstract  

High utility value of charged-particle activation analysis is exemplified by the study on carbon, nitrogen and oxygen in semiconductor silicon. A summary of the present authors' works is shown, and the equilibrium of carbon and oxygen in a silicon melt with ambient carbon monoxide is discussed. Also, a note is given about the chemical separation of18F for the3He activation analysis of various matrices.

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Abstract  

Time resolved Mössbauer spectra were measured for57Co-labelled Co/IO3/2 using a delayed coincidence technique. A life-time for unstable57Fe(II)-species formed through EC-decay was estimated to be 43±5 ns at room temperature and the initial distribution of57Fe(II)/57Fe(III) at 14.4 keV nuclear level to be 0.47±0.13. The results are discussed in terms of electron transfer from the decayed57Fe(II) atoms to iodate ions.

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Résumé  

Par l'emploi de l'analyse par activation aux particules chargées on mesure la concentration du carbone, de l'azote et de l'oxygène dans différentes qualités de silicium pour semi-conducteur. On détermine les solubilités de ces trois éléments dans le silicium solide et liquide au point de fusion. On dessine les courbes d'étalonnage pour la spectrométrie à infra-rouges du carbone et de l'oxygène dans le silicium. On montre que l'utilisation simultanée de l'analyse par activation et de la spectrométrie est efficace pour l'étude de l'état de dispersion des quantités minimes de carbone et d'oxygène dans du silicium de grande pureté. On a aussi étudié, à l'aide d'une nouvelle technique des radiotraceurs, l'évaporation des impuretés légeres du silicium en fusion. Le comportement du carbone, de l'azote et de l'oxygène dans la production du silicium pour semi-conducteur, a donc été éclairci.

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Abstract  

The irradiation of atmospheric air with high-energy protons has been performed at the 12 GeV proton synchrotron. The specific activity of 13N, one of the principal airborne radioactivities, was measured as a function of the irradiation time at a dose rate of about 6·1016 eV/g/s, and compared with the calculated values. The predominant chemical species of 13N produced were found to be 13N2and 13NO2. Their proportions were approximately 55% for 13N2 and 45% for13NO2, being almost independent of the irradiation time. Smaller quantities of 13NO and H13NO2 were also observed. Measurements of radiolytic products showed that ozone is a main product and that NO2predominates among the products of nitrogen compounds, including HNO2 and HNO3. The G-value for ozone formation in air was estimated from the experimental data as 6.4 molecules/100 eV.

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Abstract  

Samples of two older geochemical reference rocks GSJ JG-1 (granodiorite) and JB-1 (basalt) and three new ones GSJ JA-1 (andesite), JR-1 (rhyolite) and JB-2 (basalt) were subjected to determination of lanthanoid elements by radiochemical neutron activation analysis. The contents of 9 lanthanoid elements could be re-determined for the older reference rocks and those of 11 elements were determined for the new rocks. The results were compared with the previously published data.

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Abstract  

The dynamics of redox related elements (Fe, Co, Zn, and Se) were studied using instrumental neutron activation analysis as a function of rat age in the range of 4 to 16 weeks. Activity levels of glutathione peroxidase (GSH-Px), thiobarbituric acid reactive substance (TBARS) were assayed, and hydrogen peroxide (H2O2) concentrations were measured for the same liver homogenates using an X-band ESR spectrometer. The oxidative stress, the aging effect, and the mineral valance are discussed.

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Abstract  

KX-ray-gated emission Mössbauer spectra of57Co-labelled CoF2 and CoF2.2H2O were measured at room temperature, using the coincidence technique. A difference was found in the relative intensity of57Fe(II)/57Fe(III) between the X-ray-gated and non-gated emission spectra. The results are explained in terms of local radiolytic effects of water of crystallization and the chemical effects associated with the de-excitation processes caused by EC-decay.

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Abstract  

The size distributions of 38Cl, 39Cl, 82Br and 84Br aerosols generated by irradiations of argon and krypton gases containing di-octyl phthalate (DOP) aerosols with 45 MeV and 65 MeV quasi-monoenergetic neutrons were measured in order to study the formation mechanism of radioactive particles in high energy radiation fields. The effects of the size distribution of the radioactive aerosols on the size of the added DOP aerosols, the energy of the neutrons and the kinds of nuclides were studied. The observed size distributions of the radioactive particles were explained by attachment of the radioactive atoms generated by the neutron-induced reactions to the DOP aerosols.

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Abstract  

The radionuclide 67Cu was produced via the 68Zn(p,2p)67Cu reaction by irradiating enriched 68Zn targets with 70 MeV proton beam. Copper-67 was chemically separated from the zinc target by ion-exchange chromatography using Chelex-100 chelating ion-exchange resin. Procedure for recovery of the enriched 68Zn was developed. The target recovery yield of this method was evaluated to be more than 97%.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Shibata, K. Takamiya, Y. Ota, N. Nogawa, Y. Ito, T. Shibata, M. Hoshi, S. Endo, H. Hasai, and S. Fujita
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