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A superconducting transition-edge sensor (TES) microcalorimeter is an ideal X-ray detector for experiments at accelerator facilities because of good energy resolution and high efficiency. To study the performance of the TES detector with a high-intensity pulsed charged-particle beam, we measured X-ray spectra with a pulsed muon beam at the Japan Proton Accelerator Research Complex (J-PARC) in Japan. We found substantial temporal shifts of the X-ray energy correlated with the arrival time of the pulsed muon beam, which was reasonably explained by pulse pileup due to the incidence of energetic particles from the initial pulsed beam.

OGATA Koan (1810–63) was a physician and the director of Tekijuku, and he contributed to Western medicine in the late Edo period. Osaka University preserves two of his medicine chests. One of the chests, which was used in his last years (the second chest) contained 22 glass bottles and 6 wooden cylinders. These bottles and cylinders contained formulated medicines; however, about half cannot be opened because of the long-term storage. It is necessary to comprehend the physical property of both the containers and their contents for investigation of this adequate preservation method; however, destructive analysis is not allowed. To analyze the medicines sealed in the glass bottles, we focused on muonic X-ray analysis, which has high transmittance. First, we certified the analytical methods using a historical medicinal specimen preserved in Osaka University. Thereafter, we applied the method on the bottles stored in the second chest. X-ray fluorescence identified the glass of those bottles to be lead potash glass. Among these bottles, we chose the bottle with the label “甘,” which contains white powdered medication, for muonic X-ray analysis. We identified the contents of the medication in the glass to be Hg2Cl2. Through this study, we first applied muonic X-ray analysis on the medical inheritances and succeeded to detect the elements contained both in the container and in the contents of the sealed bottle. This would be a new method for nondestructive analysis of such cultural properties.

In the last decade, non-destructive elemental analysis using negative muon beams advanced significantly. This method can be used to determine the elemental composition of bulk materials without causing damage. In this study, we performed a negative muon irradiation experiment for a Northwest Africa 482 lunar meteorite (NWA482), which was installed in a stainless steel analysis chamber. The analysis chamber was filled with helium gas to suppress the background signals caused by air-scattering muons. The muonic X-rays from Al, Fe, Ca, Mg, Si, and O in the samples were detected using six high-purity germanium semiconductor detectors arranged around the analysis chamber. To correct the X-ray self-absorption effect of the samples, a Monte-Carlo simulation using Geant4 toolkit was used. Based on the quantitative analysis for muonic X-ray measurement with the correction application from the simulation, we successfully investigated the analytical sensitivity of each element in meteorites based on the NWA482 data.

In order to study the effect of muonic-Li on the µ− SR spectrum for Li battery materials, the transverse field (TF) µ− SR spectra have been measured for natural Li metal and 6Li metal samples in the temperature range between 5 and 300 K. Here, TF denotes the magnetic field perpendicular to the initial µ− spin polarization. For both samples, the TF-µ− SR spectrum showed a clear oscillation without relaxation down to the lowest temperature measured: i.e., about 5 K. This clearly excludes the scenario that the muonic-Li starts to diffuse at a certain temperature between 5 and 300 K. Although the mechanism on such a zero TF relaxation rate is not fully understood, we could ignore the contribution from the muonic Li on the asymmetry spectrum for the Li-ion battery materials at temperatures above 5 K.

To investigate the chemical effect on the muon capture process through a muon transfer reaction from a muonic hydrogen atom, the formation rate of muonic carbon atoms is measured for benzene and cyclohexane molecules in liquid samples. The muon transfer rate to carbon atoms of the benzene molecule is higher than that to the carbon atoms of the cyclohexane molecule. Such a deviation has never been observed among those molecules for gas samples. This may be because the transfers occur from the excited states of muonic hydrogen atoms in the liquid system, whereas in the gas system, all the transfers occur from the 1s (ground) state of muon hydrogen atoms. The muonic hydrogen atoms in the excited states have a larger radius than those in the 1s state and are therefore considered to be affected by the steric hindrance of the molecular structure. This indicates that the excited states of muonic hydrogen atoms contribute significantly to the chemical effects on the muon transfer reaction.

Negative and positive muon irradiation tests of static random access memories (SRAMs) were performed at Muon Science Innovation Channel (MuSIC) of Research Center for Nuclear Physics (RCNP), Osaka University. The muon-induced single event upset (SEU) cross sections for 65-nm bulk SRAMs were measured. The SRAM device was irradiated by the muon beams with average momenta ranging from 37.8 to 41.0 MeV/c at the beam exit. The incident muon fluence was measured using a one-by-one muon detection system with a plastic scintillator by taking advantage of the direct current (dc) muon beam and reliable absolute values of SEU cross sections were obtained. In addition to the measurement of the SEU cross sections, we measured muonic X-rays from the irradiated device to investigate the relation between the measured SEU cross section and the emission rate of muonic X-rays associated with the stopping position of the muons as a function of incident muon momentum. The result suggested that negative muons have a significant effect on SEUs by the emission of secondary light ions via negative muon capture reaction when negative muons stop near sensitive volumes (SVs) in SRAMs.

High-resolution X-ray spectroscopy of the highly charged muonic atoms/ions isolated in vacuum is an ideal probe to explore quantum electrodynamics under extremely strong electric fields, which is one of the major topic in fundamental atomic physics. A feasibility test measurement with a low-density neon gas target was performed by observing X-rays emitted by muonic neon via the $$5 \rightarrow 4$$ transition, $$\sim$$ 6.3 keV, using a multi-pixel array of superconducting transition-edge-sensor (TES) microcalorimeters at the J-PARC muon facility. We successfully demonstrated the feasibility of muonic atom X-ray spectroscopy with a gas target at a pressure as low as 0.1 atom using TES array under an intense pulsed muon beam.

An elemental analysis method utilizing muons has been demonstrated to be effective for non-destructive and quantitative analysis of precious bulk materials. In muon capture process, molecular structure dependence was known, and this property has the potential to be used to identify chemical structure in addition to elemental composition. Before these potential applications, fundamental studies examining the muon capture process are necessary. In this study, muon capture ratios for two iron oxide compounds, which are both important in earth science, γ-Fe2O3 (maghemite) and Fe3O4 (magnetite), were measured. The measured muon capture ratios were A(Fe/O) = 2.34 ± 0.03 and A(Fe/O) = 2.77 ± 0.03 for γ-Fe2O3 and Fe3O4, respectively.

Elemental analysis based on muonic X-rays resulting from muon irradiation provides information about bulk material composition without causing damage, which is essential in the case of precious or otherwise unreachable samples, such as in archeology and planetary science. We developed a three-dimensional (3D) elemental analysis technique by combining the elemental analysis method based on negative muons with an imaging cadmium telluride double-sided strip detector (CdTe-DSD) designed for the hard X-ray and soft $$\gamma$$ γ -ray observation. A muon irradiation experiment using spherical plastic samples was conducted at the Japan Proton Accelerator Research Complex (J-PARC); a set of projection images was taken by the CdTe-DSD, equipped with a pinhole collimator, for different sample rotation angles. The projection images measured by the CdTe-DSD were utilized to obtain a 3D volumetric phantom by using the maximum likelihood expectation maximization algorithm. The reconstructed phantom successfully revealed the 3D distribution of carbon in the bulk samples and the stopping depth of the muons. This result demonstrated the feasibility of the proposed non-destructive 3D elemental analysis method for bulk material analysis based on muonic X-rays.

The deposition of insoluble radiocesium bearing microparticles (CsMPs), which were released from the Fukushima Daiichi Nuclear Power Plant (F1NPP) accident in March 2011, has resulted in the widespread contamination of eastern Japan. Obviously, these deposited insoluble CsMPs may become the secondary contamination sources by atmospheric migration or other environmental transferring process, however, the understanding of the transport mechanism remains non-elucidation, and the relevant evidence has not been directly provided. This study, for the first time, provides the direct evidence for the resuspension of these insoluble CsMPs to the atmosphere from 1) proximity of 137Cs radioactivity and resemblance of the morphology and the elemental compositions of CsMPs in the samples of soil and aerosol derived from the same sampling site, 2) the special characteristics of the resuspended CsMPs of which the ratios of Na/Si, K/Si and/or Cs/Si were smaller than those from the initially released CsMPs collected at either long distance or near F1NPP, which can be ascribed to the slowly natural corrosion of CsMPs by the loss of the small amount of soluble contents in CsMPs and 3) high CsMPs concentration of 10 granules/gram in the surface soil of our sampling site and the observed resuspension of surface soil dust at wind gust speed higher than 4 m s-1. Specifically, fifteen single CsMPs were successfully isolated from the aerosol filters collected by unmanned high-volume air samplers at a severely polluted area in Fukushima Prefecture, about 25 km away from F1NPP, from January 2015 to September 2019. The mean diameter of these CsMPs was 1.8 ± 0.5 μm, and the average 137Cs radioactivity was 0.35 ± 0.23 Bq/granule. The contribution rate of the resuspended CsMPs to the atmospheric radiocesium was estimated from the ratio of 137Cs radioactivity of a single CsMP to that of the aerosol filter to be of 23.9 ± 15.3%. There has been no considerable decreasing trend in the annual CsMP resuspension frequency.

Variations in isotopic abundance provide useful information for various scientific fields. Herein we performed a feasibility study by non-destructive isotopic analysis of negative muons. We irradiated two lead plate samples, one with the natural isotopic composition and one enriched with 208Pb, with negative muons and observed the gamma rays from 208Tl with a half-life of 3 min generated via muon absorption by 208Pb during muon irradiation. The isotopic abundance of 208Pb in natPb was successfully determined without sample destruction from the gamma ray intensity to be 69%, which agreed well with the mass spectrometry results.

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released abundant radioactive particles into the surrounding environment. Herein, we analyzed the activity of 90Sr in these particles to estimate the contribution of this radionuclide to the overall radiation exposure and shed light on the processes that occurred during the accident. Seven radioactive particles were isolated from the dust and soil samples collected from areas surrounding the FDNPP, and the minimum/maximum 137Cs activities were determined as 224/4,100 Bq. Based on the size, specific activity, and 134Cs/137Cs activity ratios, we concluded that six of the seven radioactive particles were released from the Unit 1 reactor, while one particle was released from the Unit 3 reactor by a hydrogen explosion. Strontium-90 was detected in all radioactive particles, and the minimal/maximal 90Sr activities were determined as 0.046/1.4 Bq. 137Cs/90Sr activity ratios above 1000 were observed for all seven particles, that is, compared to 137Cs, 90Sr had negligible contribution to the overall radiation exposure. The 137Cs/90Sr activity ratios of the radioactive particles were similar to those of terrestrial environmental samples and were higher for particles released from the Unit 1 reactor than for samples collected from the Unit 1 reactor building, which indicates possibility of additional 90Sr-rich contamination after release of the particles.

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 208Pb. The observed broad X-ray peaks of the Pb Kα line around 6 MeV were deconvolved with 206Pb, 207Pb, and 208Pb isotopes, giving the isotopic ratios. The resulting isotopic ratios were consistent with those obtained from mass spectrometry.

The role of valence electrons for the muon capture process by molecules is experimentally investigated with the aid of cascade calculations. Low-momentum muons are introduced to gas targets of CO, CO2, and COS below atmospheric pressure. The initial states of captured muons are determined from the measured muonic X-ray structure of the Lyman and Balmer series. We propose that the lone pair electrons in the carbon atom of CO significantly contribute to the capture of a muon with large angular momenta.

Per-atom muon capture ratios are precisely determined from characteristic muonic X-ray measurements of three nitrogen oxide samples (NO, N2O, and NO2) at pressures below 100 kPa. A higher density of covalent electrons at the N atoms relative to the O atoms is required if we explain the experimental results using the proposed muon capture models. From molecular orbit calculations, we found that the electron distributions of only the highest occupied molecular orbitals (HOMO) are dominant at the N atoms, and the electrons in the HOMO significantly contribute to the muon capture phenomena in the nitrogen oxide molecules.

International audience; We observed electronic K x rays emitted from muonic iron atoms using superconducting transition-edge sensor microcalorimeters. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic Kα and Kβ x rays together with the hypersatellite Khα x rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the L-shell electrons, accompanied by electron side feeding. Assisted by a simulation, these data clearly reveal the electronic K- and L-shell hole production and their temporal evolution on the 10–20 fs scale during the muon cascade process.

The structural form and elemental distribution of material originating from different Fukushima Daiichi Nuclear Power Plant reactors (Units 1 and 3) is hereby examined to elucidate their contrasting release dynamics and the current in-reactor conditions to influence future decommissioning challenges. Complimentary computed X-ray absorption tomography and X-ray fluorescence data show that the two suites of Si-based material sourced from the different reactor Units have contrasting internal structure and compositional distribution. The known event and condition chronology correlate with the observed internal and external structures of the particulates examined, which suggest that Unit 1 ejecta material sustained a greater degree of melting than that likely derived from reactor Unit 3. In particular, we attribute the near-spherical shape of Unit 1 ejecta and their internal voids to there being sufficient time for surface tension to round these objects before the hot (and so relatively low viscosity) silicate melt cooled to form glass. In contrast, a more complex internal form associated with the sub-mm particulates invoked to originate from Unit 3 suggest a lower peak temperature, over a longer duration. Using volcanic analogues, we consider the structural form of this material and how it relates to its environmental particulate stability and the bulk removal of residual materials from the damaged reactors. We conclude that the brittle and angular Unit 3 particulate are more susceptible to further fragmentation and particulate generation hazard than the round, higher-strength, more homogenous Unit 1 material.

The internal magnetic field in a sodium battery compound, i.e., the paramagnet ${\mathrm{Na}}_{0.7}{\mathrm{CoO}}_{2}$, was investigated with negative muon spin rotation and relaxation (${\ensuremath{\mu}}^{\ensuremath{-}}\mathrm{SR}$), and the result was compared with the results previously obtained with ${\ensuremath{\mu}}^{+}\mathrm{SR}$. The majority of implanted ${\ensuremath{\mu}}^{\ensuremath{-}}$ is captured on an oxygen nucleus, while ${\ensuremath{\mu}}^{+}$ locates an interstitial site. Therefore, a ${\ensuremath{\mu}}^{\ifmmode\pm\else\textpm\fi{}}\mathrm{SR}$ work provides information on the internal magnetic field, which is formed by nuclear magnetic moments of $^{23}\mathrm{Na}$ and $^{59}\mathrm{Co}$, from the two different viewpoints. Besides a slight decrease in the field distribution width ($\mathrm{\ensuremath{\Delta}}$) around 300 K, the nuclear magnetic field detected with ${\ensuremath{\mu}}^{\ensuremath{-}}\mathrm{SR}$ was found to be almost static and temperature independent up to 400 K, even though Na ions are known to start to diffuse above 290 K based on ${\ensuremath{\mu}}^{+}\mathrm{SR}$, Na-NMR, neutron scattering, and electrochemical measurements. Such a discrepancy is caused by the fact that the Na contribution to $\mathrm{\ensuremath{\Delta}}$ is only about 3% at the O site whereas it is about 13% at the interstitial site, where the ${\ensuremath{\mu}}^{+}$ is presumably located.

The feasibility study for Nano-Infiltration and Transient Eutectic phase process SiC/SiC (NITE SiC/SiC)NITE SiC/SiC as a potential novel target material for pions/muons production at high-power proton accelerators facilities is in progress. Compared with graphite that is the principal target material for pions/muons production, higher transport efficiency and higher oxidation resistance can be expected. However, the residual radiation dose of NITE SiC/SiC is 400 times higher than that of graphite a year after the irradiation. To validate the simulation, the residual radionuclides of the irradiated samples have been analyzed by gamma-ray spectroscopy. To understand the thermal shock behavior, NITE-SiC/SiC was included in the HRMT35 experiment at CERN’s HiRadMat facility. In these studies, NITE SiC/SiC is proved to be a promising material for pions/muons production with the higher transport efficiency and the oxidation resistance, though the maintenance scenario has to be carefully designed due to higher residual radiation dose. The thermal shock resistance and proton-irradiation resistance of NITE SiC/SiC will be confirmed to be applied for the pions/muons production.

On March 11, 2011, the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident occurred and large amounts of radionuclides were discharged into the atmosphere. We have operated continuous aerosol samplings at four locations in Japan from the accident until the end of 2011. The activities of 90Sr and 137Cs in the aerosol samples were measured using low background liquid scintillation counters and high-purity germanium detectors, respectively. The atmospheric 90Sr and 137Cs concentrations decreased exponentially during 2011. The time variation of the 90Sr/137Cs ratio was obtained, and we found that the ratio rose from 1.2 × 10–3 in March to 1.3 × 10–1 in August 2011. One reason for the increase in the 90Sr/137Cs ratio could be the change in the primary emission source of activity at the FDNPP, which occurred near June 2011.

Elemental analysis by measurement of muonic X-rays shows great potential for analyzing the elemental composition of a bulk material at a specific depth without sample destruction. For quantitative analysis, muon capture probability is the most important parameter. In this work, the muon capture ratios and muonic X-ray intensity patterns of metal oxides for geochemically and cosmochemically important compounds, MgO, CaO, MnO and Fe3O4, were determined. The muon capture ratios of Ca/Mg and Fe/Mn were proportional to the mixing ratios of CaO/MgO and Fe3O4/MnO. From this relationship, the elemental composition can be determined from the muonic X-ray intensity ratio alone.

Although optical imaging of muon beams is a possible method for range determination, it has been limited to two-dimensional (2D) projection images. For the precise measurement of an optical image of a muon beam, three-dimensional (3D) imaging is desired. To measure a 3D optical image, we conducted optical imaging of muon beams using a plastic scintillator plate set in a water phantom. When this plate was immersed in the water phantom, irradiation with a positive muon beam was carried out from along the plate’s sides. Optical images of the scintillator plate were acquired using a charge-coupled device (CCD) camera from the side during irradiation with a positive muon beam. The imaging system was moved in 10-mm steps perpendicular to the beam direction to acquire a set of sliced optical images of the beam. These sliced images were stacked and interpolated to form a 3D optical image, and the depth and lateral profiles were evaluated. From the depth profiles derived from the 3D optical image, the Bragg peak position was estimated. The lateral profiles at the Bragg peak could also be derived. We confirmed that 3D imaging of muon beams is feasible and in fact a promising method for measuring sliced optical images at any position, which is a capability that is useful for research on muon beams as well as for future muon radiotherapy .

Although optical imaging of decayed positrons and muons can provide promising methods, it has been attempted only for muons without a collimator, and the beam characteristics with collimators, such as peak position or beam spread in depth and lateral directions, have not yet been evaluated. Therefore, we conducted optical imaging of decayed positrons and muons with different collimators. For the imaging of decayed positrons, Cherenkov-light imaging in fluorescein (FS) water was used, while imaging of a plastic scintillator block was used for the imaging of muons. We conducted these imaging trials during irradiation with 84.5-MeV/c positive muons to an FS water phantom or a plastic scintillator block using a cooled charge-coupled device (CCD) camera with each collimator of a different diameter attached to the beam port. We could measure the Cherenkov-light images of FS water of decayed positrons and optical images of muons using the plastic scintillator block for all collimators. The depth profiles of the Cherenkov-light images were slightly wider for the muons with the collimators of larger diameters, although the estimated peak depths were nearly the same for all collimators. The lateral profiles of the Cherenkov light were wider for the muons when using collimators of larger diameters. Asymmetry in the directions of positron emissions from the muons was observed for all collimators. The depth profiles of the optical image of muons using a plastic scintillator block had nearly the same shape. The estimated lateral widths of the optical images of the plastic scintillator block were the same sizes as the collimator diameters within a 1.1-mm difference at a 10-mm depth of the scintillator block, and the widths were wider at the Bragg peak. With these measured optical images, we conclude that Cherenkov-light imaging of decayed positrons in water and optical imaging of muons using a plastic scintillator block with collimators are useful methods for determining not only peak position but also beam width as well as the asymmetry of the directions of positron emissions from the muons.

Insoluble radioactive particles have been found in the terrestrial, aquatic and aerial environments. Hot particles are well known as insoluble radioactive particles found after the nuclear tests and the accident at Chernobyl Nuclear Power Plant (CNPP). Hot particles are highly radioactive pieces and mainly composed of nuclear fuel. Insoluble radioactive particles were also found following the Fukushima Daiichi Nuclear Power Plant (FNPP) accident. The particles dissipated from FNPP are almost made of amorphous silica and condensed radioactive cesium (Cs); therefore, they are referred to as radioactive Cs-bearing particles. Radioactive Cs-bearing particles show radioactivity several orders of magnitude lower than hot particles; however, their adverse effects on human health are of great concern. This article summarizes physicochemical properties of radioactive Cs-bearing particles so far reported and discusses their biological effects.

Radioactive particles were released into the environment during the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Many studies have been conducted to elucidate the chemical composition of released radioactive particles in order to understand their formation process. However, whether radioactive particles contain nuclear fuel radionuclides remains to be investigated. Here, we report the first determination of Pu isotopes in radioactive particles. To determine the Pu isotopes (239Pu, 240Pu and 241Pu) in radioactive particles derived from the FDNPP accident which were free from the influence of global fallout, radiochemical analysis and inductively coupled plasma-mass spectrometry measurements were conducted. Radioactive particles derived from unit 1 and unit 2 or 3 were analyzed. For the radioactive particles derived from unit 1, activities of 239+240Pu and 241Pu were (1.70–7.06) × 10−5 Bq and (4.10–8.10) × 10−3 Bq, respectively and atom ratios of 240Pu/239Pu and 241Pu/239Pu were 0.330–0.415 and 0.162–0.178, respectively. These ratios were consistent with the simulation results from ORIGEN code and measurements from various environmental samples. In contrast, Pu was not detected in the radioactive particles derived from unit 2 or 3. The difference in Pu contents is clear evidence towards different formation processes of radioactive particles, and detailed formation processes can be investigated from Pu analysis.

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released abundant radioactive particles into the surrounding environment. Herein, we analyzed the activity of

Radioactive particles were released into the environment during the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Many studies have been conducted to elucidate the chemical composition of released radioactive particles in order to understand their formation process. However, whether radioactive particles contain nuclear fuel radionuclides remains to be investigated. Here, we report the first determination of Pu isotopes in radioactive particles. To determine the Pu isotopes (239Pu, 240Pu and 241Pu) in radioactive particles derived from the FDNPP accident which were free from the influence of global fallout, radiochemical analysis and inductively coupled plasma-mass spectrometry measurements were conducted. Radioactive particles derived from unit 1 and unit 2 or 3 were analyzed. For the radioactive particles derived from unit 1, activities of 239+240Pu and 241Pu were (1.70–7.06) × 10−5 Bq and (4.10–8.10) × 10−3 Bq, respectively and atom ratios of 240Pu/239Pu and 241Pu/239Pu were 0.330–0.415 and 0.162–0.178, respectively. These ratios were consistent with the simulation results from ORIGEN code and measurements from various environmental samples. In contrast, Pu was not detected in the radioactive particles derived from unit 2 or 3. The difference in Pu contents is clear evidence towards different formation processes of radioactive particles, and detailed formation processes can be investigated from Pu analysis.

We observed the atmospheric resuspension of radiocaesium, derived from the Fukushima Dai-ichi Nuclear Power Plant accident, at Namie, a heavily contaminated area of Fukushima, since 2012. During the survey periods from 2012 to 2015, the activity concentrations of radiocaesium in air ranged from approximately 10−5 to 10−2 Bq per m3 and were higher in the warm season than in the cold season. Electron microscopy showed that the particles collected on filters in summer were predominantly of biological origin (bioaerosols), with which the observed radiocaesium activity concentration varied. We conducted an additional aerosol analysis based on fluorescent optical microscopic observation and high-throughput DNA sequencing technique to identify bioaerosols at Namie in 2015 summer. The concentrations of bioaerosols fluctuated the order of 106 particles per m3, and the phyla Basidiomycota and Ascomycota (true Fungi) accounted for approximately two-thirds of the bioaerosols. Moreover, the fungal spore concentration in air was positively correlated with the radiocaesium concentration at Namie in summer 2016. The bioaerosol emissions from Japanese mixed forests in the temperate zone predominately included fungal cells, which are known to accumulate radiocaesium, and should be considered an important scientific issue that must be addressed.

Muon capture isotope production (MuCIP) using negative ordinary muon capture reactions (OMC) is used to efficiently produce various kinds of nuclear isotopes for both fundamental and applied science studies. The large capture probability of muon into a nucleus, together with the high intensity muon beam, make it possible to produce nuclear isotopes in the order of 10^{9-10} per second depending on the muon beam intensity. Radioactive isotopes (RIs) produced by MuCIP are complementary to those produced by photon and neutron capture reactions and are used for various science and technology applications. MuCIP on ^{Nat}Mo by using the RCNP MuSIC \muon beam is presented to demonstrate the feasibility of MuCIP. Nuclear isotopes produced by MuCIP are evaluated by using a pre-equilibrium (PEQ) and equilibrium (EQ) proton neutron emission model. Radioactive $^{99}$Mo isotopes and the metastable ^{99m}Tc isotopes, which are used extensively in medical science, are produced by MuCIP on ^{Nat}Mo and ^{100}Mo., Comment: 21 pages, 5 figures

Range, momentum and deviation of momentum determinations of muons are important for quality assessment (QA) of beams. Imaging of annihilation radiations emitted from positrons decayed from positive muons and that of bremsstrahlung x-rays emitted from positrons and secondary electrons from positive muons are possible methods of imaging muons. However, the energies and intensities as well as position distributions of these radiations have not been obvious. Thus we calculated the energy spectrum and the distributions of annihilation radiations as well as bremsstrahlung x-rays produced in water during irradiation of positive muons using Monte Carlo simulation. The calculations were conducted for 84.5 MeV /c positive muons, which is the same beam condition used in an experimental facility at the Japan Proton Accelerator Research Complex (J-PARC). We were able to calculate the energy spectrum as well as the position distributions of annihilation radiations and bremsstrahlung x-rays. The energy spectrum showed a broad distribution of bremsstrahlung x-rays, mainly from decayed positrons with an energy range up to 50 MeV with higher intensity in low-energy bremsstrahlung x-rays. The spectrum also showed a sharp peak at 511-keV from annihilation radiations. The position distribution of annihilation radiations was wider than those of the bremsstrahlung x-rays. The position distribution of the bremsstrahlung x-rays were nearly identical to the Cerenkov-light position distribution emitted by the decayed positrons in water. We conclude that imaging of bremsstrahlung x-rays from decayed positrons by using an x-ray camera is a promising method for the QA of positive muons and that higher spatial resolution images of positron distributions will be measured than those measured by annihilation radiations.

When a negatively charged muon stopped in a material, muonic atom, which has one muon in place of an electron in the atomic system, is formed. After muon deexcitation process with muonic X-ray emission, the muon reaches to the muonic 1 s state, and the muon is absorbed in the nucleus. As a result, highly excited nucleus is produced, and the nucleus emits neutrons and gamma-rays. In this work, we determined elemental depth profiling of gold concentrations on archeological sample, an old Japanese coin, by measuring gamma-ray intensities emitted from activated nucleus with various incident muon energies.