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内容記述 |
Characteristic X-rays are emitted when an electron from an outer shell fills an inner shell vacancy, which can be generated by various processes. Characteristic X-rays resulting from inner shell vacancies created by X-ray collisions are known as “fluorescent X-rays” or “X-ray fluorescence,” and the elemental analysis tech-nique that employs them is referred to as X-ray fluorescence analysis. In contrast, characteristic X-rays arising from inner shell vacancies pro-duced by internal conversion following nuclear decay have not been assigned a specific name; we refer to these as “spontaneously emitted characteristic X-rays.” For the detection of radi-oactive nuclides, it is advantageous to use the former method for nuclides with low specific activity and the latter for those with high specific activity. In the method we recently developed, the former proved more effective for detecting uranium and neptunium, while the latter was more advantageous for detecting americium, alt-hough both methods demonstrated similar capa-bilities for detecting plutonium [1]. When a sam-ple contains strontium, the former method has difficulty detecting plutonium, which can then be identified using the latter approach. In this study, we developed a method to detect uranium via fluorescent X-rays and plutonium via spon-taneously emitted characteristic X-rays in sam-ples containing uranium, plutonium, and ameri-cium, along with a substantial amount of stronti-um.The solution containing uranium, plutonium, americium, and strontium was dropped onto 220-μm-thick filter paper cut to a diameter of 5.5 mm. The measured actinide isotopes in the sample were 234U, 235U, 238U, 239Pu, 240Pu, and 241Am, all of which are α-particle emitting nu-clides. The strontium contained in the sample was non-radioactive. The energy spectra for flu-orescent and spontaneously emitted characteris-tic X-rays were measured using MESA-50 (Hori-ba, Ltd.) and XSDD50 (TechnoAP Co. Ltd.), respectively.In the measured spectrum of fluorescent X-rays, a strong Sr Kα peak was observed along-side the U Lα peak. On the other hand, the Pu Lα peak was obscured by the Sr Kα peak and could not be observed. In the measured spectrum of spontaneously emitted characteristic X-rays, peaks associated with plutonium and americium were observed. These correspond to the U Lα and Np Lα peaks, since the daughter nuclides of 239Pu and 240Pu are 235U and 236U, respectively, and that of 241Am is 237Np.The hybrid measurement of characteristic X-rays, emitted by both X-ray collision and nuclear decay, enabled the determination of uranium and plutonium in samples containing a substan-tial amount of coexisting strontium.This study was performed under the auspices of the Secretariat of the Nuclear Regulation Au-thority, Japan.References[1]Yoshii H et al 2025 Talanta 286 127531 |
