Non-Destructive Composition Identification for Mixtures of Iron Compounds Using a Chemical Environmental Effect on a Muon Capture Process

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 gamma-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 Mossbauer 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.