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Abstract  

Alpha-ray spectrometry is at present a powerful analytical tool for the identification and assay of the transuranium elements. However, the energy resolution is not necessarily excellent and a tailing toward the lower energy side in the spectrum is observed. Then, the possibility utilizing internal conversion electron spectrometry as the improved analytical tool was examined. In this paper the construction of an internal conversion electron spectrometer with excellent energy resolution using a silicon surface barrier detector and its application to analysis of a mixture of243Cm/244Cm is described.

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Abstract  

The relative gamma-ray intensities in the energy region between 122 and 411 keV in the decay of152Eu were measured by using a Ge(Li) detector. Its efficiency calibration was carried out with the radioactive sources of241Am,57Co,203Hg,137Cs,133Ba,75Se,169Yb and192Ir.

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Abstract  

Cu-di-(2-ethylhexyl)phosphate was used as the cation exchange extractant from molten nitrate salt. IR absorption spectra of di-(2-ethylhexyl)phosphoric acid and Cu-di-(2-ethylhexyl)phosphate were compared and it was proved that the acidic form of the extractant is not Cu-di-(2-ethylhexyl)-phosphate. Using LiNO3−NH4NO3 eutectic melt, it was shown that the back-extraction of Cu2+ is a cation exchange reaction. Np(V) and Pa(V) were extracted by Cu-di-(2-ethylhexyl)phosphate from LiNO3−NaNO3−KNO3 eutectic melt. The distribution ratio of Np(V) was greater than that of Pa(V) on the contrary of their distribution ratios in the aqueous extraction system. A possible cation exchange extraction reaction was proposed for the extraction of Np(V).

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Abstract  

The effect of phenols on the ion-pair extraction of chromium(VI) as chromate anion (HCrO 4 ) with tetraphenylarsonium cation (TPA+) has been investigated. By using TPACl, chromate is extracted as an ion-pair, TPA+·HCrO 4 , into organic solvents, but its extractability into nonpolar solvents such as carbon tetrachloride is very low. The addition of several phenols greatly enhances the extractability, e.g., the distribution ratio of chromium(VI) between carbon tetrachloride and water rises 5500-fold in the presence of 0.020M 3,5-dichlorophenol in the organic phase. The enhancement was larger when using more acidic phenols and less polar solvents. From the analysis of the extraction data for the 3,5-dichlorophenol-carbon tetrachloride system, it was shown that one molecule of chromate is extracted together with one TPA+ and 1–3 phenol molecules and the extraction constants were determined. The UV spectrum indicated the extracted species including chromate ester to the TPA+·ArOCrO 3 ·mArOH (m=1,2).

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Abstract  

The synergic extraction of La(III), Nd(III), Sm(III), Tb(III) and Lu(III) with 0.1M acetylacetone (Hacac) and 1,10-phenanthroline (phen) in benzene was studied. The adduct formation constant, s, for RE(acac)3 (phen) in benzene was determined. The s decreases with inceasing atomic number of RE(III). The s in different organic solvents can be predicted in connection with the activity coefficients of the solutes, and the validity of this prediction is confirmed by good agreement with the experimental values of s in carbon tetrachloride and heptane.

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Abstract  

The oxidation of americium(III) with sodium bismuthate has been investigated in a nitric acid solution. The lower the acidity, the more rapidly the oxidation of americium(III) to americium(VI) proceeds, especially at higher temperatures. Based on this finding, a procedure was developed to oxidize americium(III) completely at low concentrations. The americium(VI) free from the excess oxidant has been found to be stable only at 0°C, irrespective of the acidity, but to be more unstable at the temperature higher than 10°C, especially at lower acidities.

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Abstract  

The isotopic ratios240Pu/239Pu in plutonium samples purified freshly and allowed to stand for a long time were determined by using a high resolution internal conversion electron spectrometer. As a result, it was proved that the above ratios can be determined accurately and precisely. The method was also examined further through a similar determination with curium samples.

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Abstract  

A new internal conversion electron spectrometer with high energy resolution has been developed using a windowless Si(Li) detector, and its characteristics are examined and discussed. As a result, it is confirmed that the energy resolutions are 0.48 keV in FWHM for 42 keV electrons and 1.43 keV for 624 keV electrons, respectively.

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Abstract  

An internal conversion electron spectrometer with high energy resolution has been constructed by using a windowless Si(Li) detector. After its characteristics were examined fundamentally, it was applied to determine the240Pu to239Pu isotope ratio. As a result, the energy resolution realized was demonstrated to be satisfactory.

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