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Journal Articles

Classification of the insoluble particles including radioactive Cs found in Okuma town and Futaba town, Fukushima prefecture

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

Journal Articles

First determination of Pu isotopes ($$^{239}$$Pu, $$^{240}$$Pu and $$^{241}$$Pu) in radioactive particles derived from Fukushima Daiichi Nuclear Power Plant accident

Igarashi, 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:2 Percentile:52.23(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 ($$^{239}$$Pu, $$^{240}$$Pu and $$^{241}$$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 $$^{239+240}$$Pu and $$^{241}$$Pu were (1.70-7.06)$$times$$10$$^{-5}$$ Bq and (4.10-8.10)$$times$$10$$^{-3}$$ Bq, respectively and atom ratios of $$^{240}$$Pu/$$^{239}$$Pu and $$^{241}$$Pu/$$^{239}$$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.

Journal Articles

Activity of $$^{90}$$Sr in fallout particles collected in the difficult-to-return zone around the Fukushima Daiichi Nuclear Power Plant

Zhang, Z.*; Igarashi, Junya*; Satou, Yukihiko; Ninomiya, Kazuhiko*; Sueki, Keisuke*; Shinohara, Atsushi*

Environmental Science & Technology, 53(10), p.5868 - 5876, 2019/05

 Times Cited Count:4 Percentile:38.8(Engineering, Environmental)

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released abundant radioactive particles into the surrounding environment. Herein, we analyzed the activity of $$^{90}$$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 $$^{137}$$Cs activities were determined as 224/4,100 Bq. Based on the size, specific activity, and $$^{134}$$Cs/$$^{137}$$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 $$^{90}$$Sr activities were determined as 0.046/1.4 Bq. $$^{137}$$Cs/$$^{90}$$Sr activity ratios above 1000 were observed for all seven particles, that is, compared to $$^{137}$$Cs, $$^{90}$$Sr had negligible contribution to the overall radiation exposure. The $$^{137}$$Cs/$$^{90}$$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 $$^{90}$$Sr -rich contamination after release of the particles.

Journal Articles

Radioactivity in soil from near the Fukushima Dai-ichi Nuclear Power Plant at five years after the accident

Ninomiya, Kazuhiko*; Satou, Yukihiko; 53 of others*

KEK Proceedings 2017-6, p.31 - 34, 2017/11

no abstracts in English

Journal Articles

Non-destructive elemental analysis of a carbonaceous chondrite with direct current Muon beam at MuSIC

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:6 Percentile:49.6(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.

Journal Articles

Online monitoring of negative muon beam profiles at J-PARC MUSE using a gated image intensifier

Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko*; Kubo, Kenya*; Kawamura, Naritoshi*; Shimomura, Koichiro*

JPS Conference Proceedings (Internet), 8, p.036014_1 - 036014_5, 2015/09

Journal Articles

Elemental analysis system with negative-muon beam

Osawa, Takahito; Ninomiya, Kazuhiko*; Yoshida, Go*; Inagaki, Makoto*; Kubo, Kenya*; Kawamura, Naritoshi*; Miyake, Yasuhiro*

JPS Conference Proceedings (Internet), 8, p.025003_1 - 025003_6, 2015/09

We report a new elemental analysis system that uses an intense negative-muon beam at J-PARC Materials and Life Science Experimental Facility, Muon Science Establishment. This paper presents the preliminary results of measurements for meteorites and standard material. The main system components are a water-cooled electromagnet, an Al flight tube, an Al sample chamber, a lead shielding body, and a Ge detector. Optimum currents for the electromagnet were determined by recording beam profiles with a CCD camera; the muon beam was shaped by collimators. The background and signal-to-noise ratio was significantly better than that obtained in a previous study, and all significant elements in the meteorite and standard samples were detected. Thus, this system can be used for muonic X-ray analysis of extraterrestrial materials.

Journal Articles

The Development of a non-destructive analysis system with negative muon beam for industrial devices at J-PARC MUSE

Tampo, Motonobu*; Hamada, Koji*; Kawamura, Naritoshi*; Inagaki, Makoto*; Ito, Takashi; Kojima, Kenji*; Kubo, Kenya*; Ninomiya, Kazuhiko*; Strasser, P.*; Yoshida, Go*; et al.

JPS Conference Proceedings (Internet), 8, p.036016_1 - 036016_6, 2015/09

Journal Articles

Nondestructive elemental depth-profiling analysis by muonic X-ray measurement

Ninomiya, Kazuhiko*; Kubo, Kenya*; Nagatomo, Takashi*; Higemoto, Wataru; Ito, Takashi; Kawamura, Naritoshi*; Strasser, P.*; Shimomura, Koichiro*; Miyake, Yasuhiro*; Suzuki, Takao*; et al.

Analytical Chemistry, 87(9), p.4597 - 4600, 2015/05

 Times Cited Count:11 Percentile:46.06(Chemistry, Analytical)

Journal Articles

Measurements of the neutron activation cross sections for Bi and Co at 386 MeV

Yashima, Hiroshi*; Sekimoto, Shun*; Ninomiya, Kazuhiko*; Kasamatsu, Yoshitaka*; Shima, Tatsushi*; Takahashi, Naruto*; Shinohara, Atsushi*; Matsumura, Hiroshi*; Satoh, Daiki; Iwamoto, Yosuke; et al.

Radiation Protection Dosimetry, 161(1-4), p.139 - 143, 2014/10

 Times Cited Count:2 Percentile:77.5(Environmental Sciences)

The neutron activation cross sections up to GeV are important for the neutron dosimetry of the radiation field in high-energy and high-intensity accelerator facilities for a project of intense spallation neutron source. But the evaluation of neutron activation cross section data is not enough above 20 MeV because experimental data are still scarce. This study aimed to measure the neutron activation cross sections of Bi and Co by using a quasi-monoenergetic neutron field. In this symposium, we will present obtained experimental cross section data with the other experimental data (neutron-induced and proton-induced), the calculated data by PHITS code and the evaluated nuclear data.

Journal Articles

A New X-ray fluorescence spectroscopy for extraterrestrial materials using muon beam

Terada, Kentaro*; Ninomiya, Kazuhiko*; Osawa, Takahito; Tachibana, Shogo*; Miyake, Yasuhiro*; Kubo, Kenya*; Kawamura, Naritoshi*; Higemoto, Wataru; Tsuchiyama, Akira*; Ebihara, Mitsuru*; et al.

Scientific Reports (Internet), 4, p.5072_1 - 5072_6, 2014/05

 Times Cited Count:20 Percentile:24.6(Multidisciplinary Sciences)

After the discovery of X-ray by Rontgen, mankind got a new eye to see through things. This fluoroscopy, so-called X-ray radiography that gives the density distribution of the inside of an object, has been applied to the vast research field such as natural/material/medical sciences, industry and technology. The recent development on the intense pulsed muon source at J-PARC MUSE (rate of 106 cps for 60 MeV/c) enabled us to pioneer a new frontier of analytical sciences. Here we report on a non-destructive elemental analysis by using muon capture. Controlling muon's momentum from 32.5 to 57.5 MeV/c. we successfully demonstrated a depth-profile analysis of light elements from several mm-thick layered materials, and non-destructive bulk analyses of meteorites containing organics. Now it is a beginning to utilize a new eye, muon radiography.

Journal Articles

Microscopic evidence for long-range magnetic ordering in the $$Gamma$$$$_{8}$$ ground quartet systems Sm$$Tr$$$$_{2}$$Al$$_{20}$$ ($$Tr$$: Ti, V, Cr)

Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko; Sakai, Akito*; Nakatsuji, Satoru*

Journal of the Physical Society of Japan, 81(Suppl.B), p.SB050_1 - SB050_4, 2012/12

Recently, $$RT_2$$Al$$_{20}$$ compounds ($$R$$: rare earth, $$T$$: transition metal) have attracted much attention due to interesting physical properties closely related to their caged-structure. Each $$R$$ ion is confined in a Frank-Kasper cage consisting of 16 Al atoms and the large coordination number leads to strong $$c$$-$$f$$ hybridization. In addition, the Frank-Kasper cage allows various multipole degrees of freedom for the $$f$$-electrons at low $$T$$ because of a highly symmetric crystalline-electric-field (CEF). Among the $$RT_2$$Al$$_{20}$$ series, Pr$$T_2$$Al$$_{20}$$ ($$T$$: Ti, V) and Sm$$T_2$$Al$$_{20}$$ ($$T$$: Ti, V, Cr) exhibit both these features. The $$Gamma_3$$ ground doublet systems Pr$$T_2$$Al$$_{20}$$ ($$T$$: Ti, V) show a phase transition at $$T_O$$ = 2.0K (Ti) and 0.6K (V). The order parameter is believed to be an electric quadrupole active in the $$Gamma_3$$ subspace. A possibility of the quadrupole Kondo effect has been discussed based on characteristic $$T$$-dependence in specific heat, resistivity, and magnetic susceptibility. The $$Gamma_8$$ ground quartet systems Sm$$T_2$$Al$$_{20}$$ ($$T$$: Ti, V, Cr) also exhibit a phase transition at $$T_O$$ = 6.4K (Ti), 2.3K (V), and 1.8K (Cr). A nuclear specific heat study in SmTi$$_2$$Al$$_{20}$$ suggests that the primary order parameter is a magnetic dipole in spite of field-insensitive nature of the phase boundary. A possible importance of a secondarily ordered octupole moment was discussed. We here present a microscopic study of PrTi$$_2$$Al$$_{20}$$ and Sm$$T_2$$Al$$_{20}$$ ($$T$$: Ti, V, Cr) using muon spin relaxation. In PrTi$$_2$$Al$$_{20}$$, no additional local field was observed in the ordered phase. This strongly supports the quadrupole ordering scenario. On the other hand, an appearance of a coherent local field was observed below $$T_O$$ in Sm$$T_2$$Al$$_{20}$$. This is consistent with the primary magnetic dipole ordering. The frequency distribution suggests that the magnetic structure is possibly different between the Sm$$T_2$$Al$$_{20}$$ compounds.

Journal Articles

Multipole and superconducting state in PrIr$$_2$$Zn$$_{20}$$ probed by muon spin relaxation

Higemoto, Wataru; Ito, Takashi; Ninomiya, Kazuhiko; Onimaru, Takahiro*; Matsumoto, Keisuke*; Takabatake, Toshiro*

Physical Review B, 85(23), p.235152_1 - 235152_4, 2012/06

 Times Cited Count:2 Percentile:87.99(Materials Science, Multidisciplinary)

We performed muon spin rotation and relaxation measurements ($$mu$$SR) in caged structural heavy fermion system PrIr$$_2$$Zn$$_{20}$$ to elucidate magnetic and superconducting properties. Temperature independent $$mu$$SR spectra were observed below 1K, indicating that the phase transition at 0.11K is non-magnetic origin, most probably pure quadrupole ordering. In the superconducting phase, no sign of unconventional superconductivity, like a broken time reversal symmetry superconductivity, is seen below $$T_c$$=0.05K. Moreover, we have observed spontaneous muon spin precession in a zero field in the paramagnetic phase below 15K, suggesting a novel coupling between $$^{141}$$Pr nuclei and muon realize in PrIr$$_2$$Zn$$_{20}$$.

Journal Articles

Development of nondestructive and quantitative elemental analysis method using calibration curve between muonic X-ray intensity and elemental composition in bronze

Ninomiya, Kazuhiko; Nagatomo, Takashi*; Kubo, Kenya*; Ito, Takashi; Higemoto, Wataru; Kita, Makoto*; Shinohara, Atsushi*; Strasser, P.*; Kawamura, Naritoshi*; Shimomura, Koichiro*; et al.

Bulletin of the Chemical Society of Japan, 85(2), p.228 - 230, 2012/02

 Times Cited Count:13 Percentile:52(Chemistry, Multidisciplinary)

Elemental analysis of bulk materials can be performed by detecting the high-energy X-rays emitted from muonic atoms. Muon irradiation of standard bronze samples was performed to determine the muon capture probabilities for the elemental components from muonic X-ray spectra. Nondestructive elemental analysis of an ancient Chinese coin was also performed.

Journal Articles

$$mu$$SR evidence of nonmagnetic order and $$^{141}$$Pr hyperfine-enhanced nuclear magnetism in the cubic $$Gamma_3$$ ground doublet system PrTi$$_2$$Al$$_{20}$$

Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko; Luetkens, H.*; Baines, C.*; Sakai, Akito*; Nakatsuji, Satoru*

Journal of the Physical Society of Japan, 80(11), p.113703_1 - 113703_4, 2011/11

 Times Cited Count:26 Percentile:19.99(Physics, Multidisciplinary)

Journal Articles

Absence of pure quadrupole ordering in SmSn$$_3$$; Dipole-dipole and quadrupole-quadrupole interactions in Sm-based compounds

Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko; Suzuki, Hiroyuki*

Physical Review B, 84(6), p.064411_1 - 064411_5, 2011/08

 Times Cited Count:3 Percentile:81.09(Materials Science, Multidisciplinary)

Journal Articles

Possible long-periodic magnetic structure in SmPb$$_{3}$$

Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko; Amato, A.*; Sugai, Takashi; Haga, Yoshinori; Suzuki, Hiroyuki*

Journal of the Physical Society of Japan, 80(Suppl.A), p.SA075_1 - SA075_3, 2011/07

A series of cubic SmX$$_3$$ (X=In, Sn, Pb) compounds has a $$Gamma_8$$ crystalline-electric-field ground state with various multipolar degrees of freedom. These show phase transitions at low temperatures and a possibility of multipolar ordering has been suggested. However, no microscopic experimental data is available so far and details of the ordered states have not been clarified yet. We performed muon spin relaxation measurements in order to elucidate nature of multipoles in these systems. A breaking of time-reversal symmetry was observed in all the ordered phases in zero applied field, indicating the primary order parameters are magnetic. We also obtained information about the ordered structures from a microscopic point of view.

Journal Articles

Incommensurate-to-commensurate magnetic phase transition in SmIn$$_3$$ observed by muon spin relaxation

Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko; Luetkens, H.*; Sugai, Takashi; Haga, Yoshinori; Suzuki, Hiroyuki*

Journal of the Physical Society of Japan, 80(3), p.033710_1 - 033710_4, 2011/03

 Times Cited Count:4 Percentile:62.51(Physics, Multidisciplinary)

Magnetic susceptibility $$chi$$ and muon spin relaxation ($$mu$$SR) measurements are reported on SmIn$$_3$$ with a $$Gamma_8$$ ground state. Anomalies corresponding to successive phase transitions were observed in $$chi$$ at $$T_{rm I}sim$$16.5 K, $$T_{rm II}sim$$15.1 K, and $$T_{rm III}sim$$14.7 K. A spontaneous local magnetic field was detected below $$T_{rm I}$$ using the $$mu$$SR technique on the contrary to a pure quadrupolar ordering scenario proposed in the phase between $$T_{rm I}$$ and $$T_{rm II}$$. This result clearly indicates that the primary order parameters in all the ordered phases are magnetic. The local field distribution changes at around $$T_{rm II}$$ from a continuous broad one to a sharp one with decreasing temperature, suggesting that an incommensurate to commensurate magnetic phase transition takes place at this temperature. A possible magnetic structure in the ground state and importance of multipolar interactions are discussed.

Journal Articles

Measurement of neutron cross sections for yttrium and terbium at 287 MeV

Sekimoto, Shun*; Utsunomiya, Takashi*; Yashima, Hiroshi*; Ninomiya, Kazuhiko*; Omoto, Takashi*; Nakagaki, Reiko*; Shima, Tatsushi*; Takahashi, Naruto*; Shinohara, Atsushi*; Kinoshita, Norikazu*; et al.

Progress in Nuclear Science and Technology (Internet), 1, p.89 - 93, 2011/02

In this work, we tried to determine reaction cross sections for Y and Tb induced by neutrons at 300 MeV, which have never been reported. The irradiations were carried out using neutrons produced through $$^{7}$$Li(p, n) reaction at N0 beam line in the Research Center for Nuclear Physics (RCNP), Osaka University. To estimate quasi-monoenergetic neutron induced cross sections, the target stacks of Y and Tb were irradiated on the two angles of 0 degree and 30 degree for the axis of the primary proton beam. Neutron cross sections were estimated by subtracting the activities produced in the samples placed on 30 degree from those of 0 degree to correct the contribution of the low energy tail in the neutron spectrum.

Journal Articles

Development of elemental analysis by muonic X-ray measurement in J-PARC

Ninomiya, Kazuhiko; Nagatomo, Takashi*; Kubo, Kenya*; Strasser, P.*; Kawamura, Naritoshi*; Shimomura, Koichiro*; Miyake, Yasuhiro*; Saito, Tsutomu*; Higemoto, Wataru

Journal of Physics; Conference Series, 225, p.012040_1 - 012040_4, 2010/06

 Times Cited Count:9 Percentile:5.42

Muon irradiation and muonic X-ray detection can be applied to non-destructive elemental analysis. In this study, in order to develop the elemental analysis by muonic X-ray measurement we constructed a new X-ray measuring system in J-PARC muon facility. We performed muon irradiation for Tempo-koban (Japanese old coin) for test experiment of elemental analysis.

52 (Records 1-20 displayed on this page)