A muonic hydrogen atom, which consists of a negative muon and a proton, behaves as an electrically neutral particle. As such, it can approach another nucleus without Coulomb repulsion, allowing the muon to be directly transferred to inner muon levels of the nucleus and form a muonic atom. We studied muonic atom formation via this muon transfer process in two chemical environments; CO and CO2 (CO has one oxygen atom and one triple bond, and CO2 has two oxygen and two double bond), to examine the effects of the environments on muonic atom formation. The muon capture probability and intensity pattern of muonic Xrays for carbon and oxygen atoms were determined through measurement of muonic Xrays emitted after muonic atom formation. By comparing the results of CO and CO2 to each other, we found that the muon capture probabilities and initial muon quantum levels for carbon and oxygen atoms resulting from the muon transfer process do not depend on the chemical environment, though a significant effect of the chemical environmental was observed for the direct muon capture process. The effect of the chemical environmental in muonic atom formation via the muon transfer process is too small to detect statistically significant in our experimental system.
A three-dimensional (3D) X-ray computed tomography (CT) instrument for radiation education was developed. The structure of the instrument is such that the main parts, i.e. the X-ray source, specimen rotation stage, and two-dimensional detector can be easily observed. An experiment using a fruit of green pepper as a specimen was performed. CT images and intermediate steps for obtaining them, i.e. radiographs, sinograms after Radon transform, and real and imaginary parts of Fourier components in reciprocal space during inverse Radon transform are shown. We propose that these images will help students to understand the principle and mechanism of X-ray CT instruments visually.
To elucidate pathways of radioactive caesium contamination of persimmon fruit, we investigated translocation via the calyx. We treated calyces of immature and mature fruits (at either stage and both stages) with water containing caesium-137 (1000 Bq/kg) and measured concentrations in the calyx, pericarp, and flesh with a germanium semiconductor detector. All treated fruits had higher levels of radioactive caesium in all tissues than untreated fruits at harvest. The translocated radioactive caesium was retained in the fruit and not retranslocated. These results indicate that radioactive caesium is translocated via the calyx of persimmon at all stages of fruit development and is accumulated in the flesh.
Nerve growth factor (NGF) induces neurite extension in PC12 cells, a well-known model of neuronal differentiation. Previous reports have shown that irradiation activates the extracellular signal-regulated kinase 1/2 (ERK), which is a mainstream pathway for NGF signaling. This suggests that the neurite extension may possibly be enhanced by Xray irradiation. Therefore, we observed NGF-induced neurite extension with Xray irradiation in PC12 cells. At the start of the NGF treatment, Xray irradiation was performed simultaneously for the first 5 min. After 5 days, the irradiation at 500 mGy promoted NGF-induced neurite extension, and increased phosphorylation of ERK, but not of the NGF receptor. The phosphorylation of epidermal growth factor (EGF) receptor, a stimulatory growth signal in PC12 cells, was also enhanced by irradiation. Interestingly, AG1478, an inhibitor of EGF receptor tyrosine kinase, inhibited the irradiation-induced promotion of neurite extension. These results suggest that irradiation activate EGF receptor tyrosine kinase and promote NGF-induced neurite extension via the cross talk between NGF and EGF signaling.
The principles of polarized neutron scattering are introduced and examples of polarized neutron inelastic scattering experiments on spin dynamics investigation are presented. These examples should demonstrate the importance of the polarized neutron utilization for the investigation of non-trivial magnetic ground and excited states in frustrated and low dimensional quantum spin systems.