Elemental isotopic ratios are measured in various research fields and provide useful information regarding age, origin, geological and biological activities, ancient climate, etc. Here, we report a new isotopic analysis method without sample destruction using muon-induced characteristic X-rays. We demonstrated this method by conducting muon-beam irradiation experiments on two Pb plates with different isotopic ratios: natural isotopic composition and artificially enriched 208 Pb. The observed broad X-ray peaks of the Pb K α line around 6 MeV were deconvolved with 206 Pb, 207 Pb, and 208 Pb isotopes, giving the isotopic ratios. The resulting isotopic ratios were consistent with those obtained from mass spectrometry.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
The non-destructive investigation of the chemical state of elements within a material is urgently needed in various scientific research fields. In recent years, non-destructive elemental analysis methods using muons have been developed. These methods identify elements by measuring muonic X-rays emitted from muonic atoms formed by the muon irradiation of the material. Interestingly, muonic atom formation processes are slightly influenced by the chemical state of the muon-capturing atom, and as a result, the muon capture probability of each element and the muonic X-ray emission intensity change depending on the chemical state. By utilizing this effect, it may be possible to know the chemical state at the same time as elemental analysis. In this study, the compositions of γ-Fe2O3 and Fe3O4 in an ironsand sample were determined using two approaches: muonic X-ray intensity ratios and muon capture ratios. The mixing ratios obtained from the two approaches were consistent with each other and consistent with results of the Mössbauer technique, a completely different analysis method. In this study, non-destructive chemical state analysis using muons was successfully demonstrated, and this method is promising for applications in various research fields.
Non-destructive identification of bismuth metal sealed in an aluminum box was conducted by the muonic X-ray analysis method as a simulation experiment for nuclear fuel materials sealed in a container. This method can identify elements of bulk materials non-destructively and selectively position them by measuring characteristic X-rays emitted from muonic atoms that form after muon irradiation. A pulse mode muon beam induces an abundance of muonic X-ray photons within microseconds, which suppress the background signals from naturally occurring radioactive nuclides and the sample by a factor of 10 -4 . This method can be applied in many applications related to the detection of nuclear materials, nuclear forensics, and debris processing of nuclear accidents.
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