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Ninomiya, Kazuhiko*; Osawa, Takahito; Terada, Kentaro*; Wada, Taiga*; Nagasawa, Shunsaku*; Chiu, I.-H.; Nakamura, Tomoki*; 40 of others*
Meteoritics & Planetary Science, 59(8), p.2044 - 2057, 2024/08
Times Cited Count：1 Percentile：73.79(Geochemistry & Geophysics)Samples from asteroid Ryugu, brought back by asteroid explorer Hayabusa2 are important for investigating the origin and evolution of the solar system. Here, we report the elemental compositions of a 123 mg Ryugu sample determined with a nondestructive muon elemental analysis method. This method is a powerful tool for determining bulk chemical composition, including light elements such as C, N, and O. From the muonic X-ray spectra with three carbonaceous chondrites, the relationship between the elemental composition and muonic X-ray intensity was determined for each element. Calibration curves showed linearity, and the elemental composition of Ryugu was quantitatively determined. The results reflect the average bulk elemental composition of asteroid Ryugu owing to the large amount of samples. Ryugu has an elemental composition similar to that of Orgueil (CI1), and should be classified as CI1. However, the O/Si ratio of Ryugu is 25% lower than that of Orgueil, indicating that Orgueil may have been seriously contaminated by terrestrial materials after its fall to Earth. These results indicate that the Ryugu sample is more representative than the CI chondrites as a solid material of the solar system.
Ninomiya, Kazuhiko*; Kubo, Kenya*; Inagaki, Makoto*; Yoshida, Go*; Takeshita, Soshi*; Tampo, Motonobu*; Shimomura, Koichiro*; Kawamura, Naritoshi*; Strasser, P.*; Miyake, Yasuhiro*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 333(7), p.3445 - 3450, 2024/07
Times Cited Count：0 Percentile：0.00(Chemistry, Analytical)Mizuno, Rurie*; Niikura, Megumi*; Saito, Takeshi*; Matsuzaki, Teiichiro*; Sakurai, Hiroyoshi*; Amato, A.*; Asari, Shunsuke*; Biswas, S.*; Chiu, I.-H.; Gianluca, J.*; et al.
Nuclear Instruments and Methods in Physics Research A, 1060, p.169029_1 - 169029_14, 2024/03
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)Ninomiya, Kazuhiko*; Kubo, Kenya*; Inagaki, Makoto*; Yoshida, Go*; Chiu, I.-H.; Kudo, Takuto*; Asari, Shunsuke*; Sentoku, Sawako*; Takeshita, Soshi*; Shimomura, Koichiro*; et al.
Scientific Reports (Internet), 14, p.1797_1 - 1797_8, 2024/01
Times Cited Count：0 Percentile：0.00(Multidisciplinary Sciences)The amount of C in steel, which is critical in determining its properties, is strongly influenced by steel production technology. We propose a novel method of quantifying the bulk C content in steel non-destructively using muons. This revolutionary method may be used not only in the quality control of steel in production, but also in analyzing precious steel archaeological artifacts. A negatively charged muon forms an atomic system owing to its negative charge, and is finally absorbed into the nucleus or decays to an electron. The lifetimes of muons differ significantly, depending on whether they are trapped by Fe or C atoms, and identifying the elemental content at the muon stoppage position is possible via muon lifetime measurements. The relationship between the muon capture probabilities of C/Fe and the elemental content of C exhibits a good linearity, and the C content in the steel may be quantitatively determined via muon lifetime measurements. Furthermore, by controlling the incident energies of the muons, they may be stopped in each layer of a stacked sample consisting of three types of steel plates with thicknesses of 0.5 mm, and we successfully determined the C contents in the range 0.20 - 1.03 wt% depth-selectively, without sample destruction.
Chiu, I.-H.; Terada, Kentaro*; Osawa, Takahito; Park, C.*; Takeshita, Soshi*; Miyake, Yasuhiro*; Ninomiya, Kazuhiko*
Meteoritics & Planetary Science, 58(9), p.1333 - 1344, 2023/09
Times Cited Count：0 Percentile：0.00(Geochemistry & Geophysics)Osawa, Takahito; Nagasawa, Shunsaku*; Ninomiya, Kazuhiko*; Takahashi, Tadayuki*; Nakamura, Tomoki*; Wada, Taiga*; Taniguchi, Akihiro*; Umegaki, Izumi*; Kubo, Kenya*; Terada, Kentaro*; et al.
ACS Earth and Space Chemistry (Internet), 7(4), p.699 - 711, 2023/04
Times Cited Count：5 Percentile：82.80(Chemistry, Multidisciplinary)The concentrations of carbon and other major elements in asteroid samples provide very important information on the birth of life on the Earth and the solar-system evolution. Elemental analysis using muonic X-rays is one of the best analytical methods to determine the elemental composition of solid materials, and notably, is the only method to determine the concentration of light elements in bulk samples in a non-destructive manner. We developed a new analysis system using muonic X-rays to measure the concentrations of carbon and other major elements in precious and expectedly tiny samples recovered from the asteroid Ryugu by spacecraft Hayabusa2. Here we report the development process of the system in 4 stages and their system configurations, The analysis system is composed of a stainless-steel analysis chamber, an acrylic glove box for manipulating asteroid samples in a clean environment, and Ge semiconductor detectors arranged to surround the analysis chamber. The performance of the analysis system, including the background level, which is crucial for the measurement, was greatly improved from the first stage to the later ones. Our feasibility study showed that the latest model of our muonic X-ray analysis system is capable of determining the carbon concentration in Hayabusa2's sample model with an uncertainty of less than 10 percent in a 6-day measurement.
Chiu, I.-H.; Terada, Kentaro*; Osawa, Takahito; Park, C.*; Takeshita, Soshi*; Miyake, Yasuhiro*; Ninomiya, Kazuhiko*
Journal of Physics; Conference Series, 2462, p.012004_1 - 012004_6, 2023/03
Times Cited Count：1 Percentile：75.74(Physics, Applied)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.
Tang, P.*; Kita, Kazuyuki*; Igarashi, Yasuhito*; Satou, Yukihiko; Hatanaka, Kotaro*; Adachi, Koji*; Kinase, Takeshi*; Ninomiya, Kazuhiko*; Shinohara, Atsushi*
Progress in Earth and Planetary Science (Internet), 9(1), p.17_1 - 17_15, 2022/03
Times Cited Count：6 Percentile：51.49(Geosciences, Multidisciplinary)Okumura, Takuma*; Azuma, Toshiyuki*; Bennet, D. A.*; Caradonna, P.*; Chiu, I.-H.*; Doriese, W. B.*; Durkin, M. S.*; Fowler, J. W.*; Gard, J. D.*; Hashimoto, Tadashi; et al.
IEEE Transactions on Applied Superconductivity, 31(5), p.2101704_1 - 2101704_4, 2021/08
Times Cited Count：1 Percentile：8.46(Engineering, Electrical & Electronic)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.
X raysOkumura, Takuma*; Azuma, Toshiyuki*; Bennet, D. A.*; Caradonna, P.*; Chiu, I. H.*; Doriese, W. B.*; Durkin, M. S.*; Fowler, J. W.*; Gard, J. D.*; Hashimoto, Tadashi; et al.
Physical Review Letters, 127(5), p.053001_1 - 053001_7, 2021/07
Times Cited Count：15 Percentile：79.06(Physics, Multidisciplinary)We observed electronic X rays emitted from muonic iron atoms using a superconducting transition-edge-type sensor microcalorimeter. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic 
and 
X rays together with the hypersatellite X rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the 
-shell electrons, accompanied by electron side-feeding. Assisted by a simulation, this data clearly reveals the electronic - and -shell hole production and their temporal evolution during the muon cascade process.
Martin, P. G.*; Jones, C. P.*; Bartlett, S.*; Ignatyev, K.*; Megson-Smith, D.*; Satou, Yukihiko; Cipiccia, S.*; Batey, D. J.*; Rau, C.*; Sueki, Keisuke*; et al.
Scientific Reports (Internet), 10, p.22056_1 - 22056_17, 2020/12
Times Cited Count：2 Percentile：11.76(Multidisciplinary Sciences)Igarashi, Junya*; Zhang, Z. J.*; Ninomiya, Kazuhiko*; Shinohara, Atsushi*; Satou, Yukihiko; Minowa, Haruka*; Yoshikawa, Hideki
KEK Proceedings 2019-2, p.54 - 59, 2019/11
no abstracts in English
Pu, 
Pu and 
Pu) in radioactive particles derived from Fukushima Daiichi Nuclear Power Plant accidentIgarashi, Junya*; Zheng, J.*; Zhang, Z.*; Ninomiya, Kazuhiko*; Satou, Yukihiko; Fukuda, Miho*; Ni, Y.*; Aono, Tatsuo*; Shinohara, Atsushi*
Scientific Reports (Internet), 9(1), p.11807_1 - 11807_10, 2019/08
Times Cited Count：22 Percentile：64.15(Multidisciplinary Sciences)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 (Pu, Pu and Pu) 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 
Pu and Pu were (1.70-7.06)
10
Bq and (4.10-8.10)10
Bq, respectively and atom ratios of Pu/Pu and Pu/Pu 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.
Sr in fallout particles collected in the difficult-to-return zone around the Fukushima Daiichi Nuclear Power PlantZhang, Z.*; Igarashi, Junya*; Satou, Yukihiko; Ninomiya, Kazuhiko*; Sueki, Keisuke*; Shinohara, Atsushi*
Environmental Science & Technology, 53(10), p.5868 - 5876, 2019/05
Times Cited Count：20 Percentile：60.68(Engineering, Environmental)The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released abundant radioactive particles into the surrounding environment. Herein, we analyzed the activity of Sr 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 
Cs activities were determined as 224/4,100 Bq. Based on the size, specific activity, and 
Cs/Cs 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 Sr activities were determined as 0.046/1.4 Bq. Cs/Sr activity ratios above 1000 were observed for all seven particles, that is, compared to Cs, Sr had negligible contribution to the overall radiation exposure. The Cs/Sr 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 Sr -rich contamination after release of the particles.
, and COSYoshida, Go*; Ninomiya, Kazuhiko*; Inagaki, Makoto*; Higemoto, Wataru; Strasser, P.*; Kawamura, Naritoshi*; Shimomura, Koichiro*; Miyake, Yasuhiro*; Miura, Taichi*; Kubo, Kenya*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 320(2), p.283 - 289, 2019/05
Times Cited Count：4 Percentile：37.41(Chemistry, Analytical)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 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.
Ninomiya, Kazuhiko*; Ito, Takashi; Higemoto, Wataru; Kawamura, Naritoshi*; Strasser, P.*; Nagatomo, Takashi*; Shimomura, Koichiro*; Miyake, Yasuhiro*; Kita, Makoto*; Shinohara, Atsushi*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 319(3), p.767 - 773, 2019/03
Times Cited Count：12 Percentile：76.41(Chemistry, Analytical)Sugiyama, Jun*; Umegaki, Izumi*; Nozaki, Hiroshi*; Higemoto, Wataru; Hamada, Koji*; Takeshita, Soshi*; Koda, Akihiro*; Shimomura, Koichiro*; Ninomiya, Kazuhiko*; Kubo, Kenya*
Physical Review Letters, 121(8), p.087202_1 - 087202_5, 2018/08
Times Cited Count：18 Percentile：72.35(Physics, Multidisciplinary)Ninomiya, Kazuhiko*; Satou, Yukihiko; 53 of others*
KEK Proceedings 2017-6, p.31 - 34, 2017/11
no abstracts in English
Terada, Kentaro*; Sato, Akira*; Ninomiya, Kazuhiko*; Kawashima, Yoshitaka*; Shimomura, Koichiro*; Yoshida, Go*; Kawai, Yosuke*; Osawa, Takahito; Tachibana, Shogo*
Scientific Reports (Internet), 7(1), p.15478_1 - 15478_6, 2017/11
Times Cited Count：22 Percentile：69.51(Multidisciplinary Sciences)Electron- or X-ray-induced characteristic X-ray analysis has been widely used to determine chemical compositions of materials in vast research fields. In recent years, analysis of characteristic X-rays from muonic atoms, in which a muon is captured, has attracted attention because both a muon beam and a muon-induced characteristic X-ray have high transmission abilities. Here we report the first non-destructive elemental analysis of a carbonaceous chondrite using one of the world-leading intense direct current muon beam source (MuSIC; MUon Science Innovative Channel). We successfully detected characteristic muonic X-rays of Mg, Si, Fe, O, S and C from Jbilet Winselwan CM chondrite, of which carbon content is about 2 wt percent, and the obtained elemental abundance pattern was consistent with that of CM chondrites.
Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko*; Kubo, Kenya*; Kawamura, Naritoshi*; Shimomura, Koichiro*
JPS Conference Proceedings (Internet), 8, p.036014_1 - 036014_5, 2015/09
