International Journal of PIXE

In this paper, we measured more than 4200 beard samples collected from a single person every day over a 12-year period and analyzed them based on a standard-free method. It was found that the sulfur concentration remained almost constant from a long-term perspective but showed small periodic elevations. Silicone, phosphorus and rubidium showed significant periodic changes with a cycle of several years. While manganese, strontium and molybdenum seemed to show long-term changes, there were no significant differences due to their large standard deviations. Concerning seasonal changes, silicone and phosphorus showed decreasing trends in summer, albeit without significant differences. The bromine concentration showed clear seasonal variations, rising in winter and falling in summer, suggesting the possible influence of seasonal changes in the elemental components in the airborne particles that pass over to Japan from the Asian Continent. These findings confirmed that beard analyses are useful not only for evaluating changes in trace element concentrations in the human body but also for clarifying the main pathways of the intake of these elements.

A thallium bromide (TlBr) gamma-ray detector was developed for particle-induced gamma-ray emission (PIGE) applications. The PIGE spectrum of a lithium fluoride (LiF) crystal was obtained for the first time using the TlBr detector. This detector was fabricated using a zone-purified crystal with dimensions of approximately 2mm × 2mm × 5mm. An energy resolution of 2.3% full-width at half maximum for 511 keV gamma rays was obtained from the detector at room temperature. The LiF crystal target was irradiated with a 20 MeV proton beam at the Aomori Prefecture Quantum Science Center. Full-energy peaks of 478 keV and 197 keV were successfully detected from lithium and fluorine, respectively, using the TlBr detector in the PIGE experiment.

We subjected ¹³⁷Cs-contaminated soil to stirring and particle classification to reduce the contaminated soil volume. ¹³⁷Cs activity as a function of particle diameter changed drastically as the weight ratio of soil/water varied; 85% of all ¹³⁷Cs was adsorbed to particles of minimum diameter after stirring. Soil argillites (smectites, vermiculites, and illites) adsorbed ¹³⁷Cs. We used X-ray diffraction (XRD) analysis to measure the soil contents; the ¹³⁷Cs distribution as a function of soil particle diameter mirrored the smectite levels revealed by the XRD peak intensities. Thus, smectic was the main absorbent of ¹³⁷Cs.

The Chinese yam is a major component of the Japanese diet consumed in raw and cooked form. It is important to determine the nutrient contents of yam, which contains high potassium levels; a simple measurement method is required. We performed proton-induced X-ray emission (PIXE) analysis of fully grown and immature yams. Analysis of the yam trunk, skin, and hair roots revealed that the skin potassium concentration was 10-fold higher than that of the trunk; consumption of the skin is thus recommended. Longitudinal measurements of mineral concentrations in a growing yam revealed that the concentrations increased in the growth direction.

We subjected white birch milk to X-ray emission analysis. The mineral levels changed over time. White birch seasonality (sprouting in early spring and fruition in autumn) affected the mineral levels.