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Journal Articles

Guidance for ${it in situ}$ gamma spectrometry intercomparison based on the information obtained through five intercomparisons during the Fukushima mapping project

Mikami, Satoshi; Ishikawa, Daisuke*; Matsuda, Hideo*; Hoshide, Yoshifumi*; Okuda, Naotoshi*; Sakamoto, Ryuichi*; Saito, Kimiaki

Journal of Environmental Radioactivity, 210, p.105938_1 - 105938_7, 2019/12

 Times Cited Count:0 Percentile:100(Environmental Sciences)

Five intercomparisons of in situ $$gamma$$ spectrometry by 6-7 participating teams have been conducted between December 2011 and August 2015 at sites in Fukushima prefecture which affected by the fallout of FDNPS accident occurred in March 2011. The evaluated deposition densities agreed within 5-6% in terms of coefficient of variation (CV) for radiocesium ($$^{134}$$Cs and $$^{137}$$Cs), by our best achievement, and the ratio of $$^{134}$$Cs/$$^{137}$$Cs in deposition density agreed within 1-2% in CV, through five intercomparisons. These results guarantee the accuracy of the measurements of the mapping project. Two different methods for intercomparison were conducted: (1) sequential measurements at an identical point; and (2) simultaneous measurements in a narrow area within 3 m radius. In a comparison between the two methods at a site, no significant difference was observed between the results. The standard protocols for the two different intercomparison methods were proposed based on our experience.

Journal Articles

The Deposition densities of radiocesium and the air dose rates in undisturbed fields around the Fukushima Dai-ichi nuclear power plant; Their temporal changes for five years after the accident

Mikami, Satoshi; Tanaka, Hiroyuki*; Matsuda, Hideo*; Sato, Shoji*; Hoshide, Yoshifumi*; Okuda, Naotoshi*; Suzuki, Takeo*; Sakamoto, Ryuichi*; Ando, Masaki; Saito, Kimiaki

Journal of Environmental Radioactivity, 210, p.105941_1 - 105941_12, 2019/12

 Times Cited Count:9 Percentile:16.15(Environmental Sciences)

The deposition densities of radiocesium and the air dose rates were repeatedly measured in a large number of undisturbed fields within the 80km zone that surrounds the Fukushima Dai-ichi Nuclear Power Plant site between 2011 and 2016, and features of their temporal changes were clarified. The average air dose rate excluding background radiation in this zone decreased to about 20% of the initial value during the period from June 2011 to August 2016, which was essentially a result of the radioactive decay of $$^{134}$$Cs with a half-life of 2.06y. The air dose rate reduction was faster than that expected from the decay of radiocesium by a factor of about two, with most of this reduction being attributed to the penetration of radiocesium into the soil. The average deposition densities of $$^{134}$$Cs and $$^{137}$$Cs in fields that were not decontaminated were found to have decreased nearly according to their expected radioactive decay, which indicated that the movement of radiocesium in the horizontal direction was relatively small. The effect of decontamination was apparently observed in the measurements of air dose rates and deposition densities. Nominally, the average air dose rates in the measurement locations were reduced by about 20% by decontamination and other human activities, of which accurate quantitative analysis is and continue to be a challenge.

Journal Articles

Vortex rectenna powered by environmental fluctuations

Lustikova, J.*; Shiomi, Yuki*; Yokoi, Naoto*; Kabeya, Noriyuki*; Kimura, Noriaki*; Ienaga, Koichiro*; Kaneko, Shinichi*; Okuma, Satoshi*; Takahashi, Saburo*; Saito, Eiji

Nature Communications (Internet), 9, p.4922_1 - 4922_6, 2018/11

 Times Cited Count:9 Percentile:20.58(Multidisciplinary Sciences)

Journal Articles

New precise measurement of muonium hyperfine structure interval at J-PARC

Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 Times Cited Count:3 Percentile:6.53

Journal Articles

New muonium HFS measurements at J-PARC/MUSE

Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12

 Times Cited Count:5 Percentile:6.99

Journal Articles

Holographic realization of ferromagnets

Yokoi, Naoto*; Ishihara, Masafumi*; Sato, Koji*; Saito, Eiji

Physical Review D, 93(2), p.026002_1 - 026002_6, 2016/01

 Times Cited Count:9 Percentile:44(Astronomy & Astrophysics)

Journal Articles

In situ $$gamma$$ spectrometry intercomparison in Fukushima, Japan

Mikami, Satoshi; Sato, Shoji*; Hoshide, Yoshifumi*; Sakamoto, Ryuichi*; Okuda, Naotoshi*; Saito, Kimiaki

Hoken Butsuri, 50(3), p.182 - 188, 2015/09

Intercomparison of in situ $$gamma$$ spectrometry was organized at a site contaminated by the radioactive fallout that originated from the Fukushima Dai-ichi Nuclear Power Plant accident. This intercomparison was conducted by eight teams from four different institutions, which have contributed to the government-led project to construct distribution maps of radionuclides deposited on the ground soil. The resultant $$^{134}$$Cs and $$^{137}$$Cs inventories evaluated by the participants agreed within 6% of the coefficient of variation, after correction for inhomogeneous distribution of the air dose rate. The evaluated $$^{40}$$K inventories agreed within 4% of the coefficient of variation. The authors estimated that these results were in good agreement for creating distribution maps of the radionuclide inventory in the ground soil.

Journal Articles

Nitrogen K-edge X-ray absorption near edge structure of pyrimidine-containing nucleotides in aqueous solution

Shimada, Hiroyuki*; Minami, Hirotake*; Okuizumi, Naoto*; Sakuma, Ichiro*; Ukai, Masatoshi*; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro*; Saito, Yuji

Journal of Chemical Physics, 142(17), p.175102_1 - 175102_9, 2015/05

AA2015-0073.pdf:1.15MB

 Times Cited Count:8 Percentile:56.01(Chemistry, Physical)

Journal Articles

The Air dose rate around the Fukushima Dai-ichi Nuclear Power Plant; Its spatial characteristics and temporal changes until December 2012

Mikami, Satoshi; Maeyama, Takeshi*; Hoshide, Yoshifumi*; Sakamoto, Ryuichi*; Sato, Shoji*; Okuda, Naotoshi*; Sato, Tetsuro*; Takemiya, Hiroshi; Saito, Kimiaki

Journal of Environmental Radioactivity, 139, p.250 - 259, 2015/01

 Times Cited Count:36 Percentile:12.9(Environmental Sciences)

Journal Articles

Spatial distributions of radionuclides deposited onto ground soil around the Fukushima Dai-ichi Nuclear Power Plant and their temporal change until December 2012

Mikami, Satoshi; Maeyama, Takeshi*; Hoshide, Yoshifumi*; Sakamoto, Ryuichi*; Sato, Shoji*; Okuda, Naotoshi*; Demongeot, S.*; Gurriaran, R.*; Uwamino, Yoshitomo*; Kato, Hiroaki*; et al.

Journal of Environmental Radioactivity, 139, p.320 - 343, 2015/01

 Times Cited Count:57 Percentile:5.87(Environmental Sciences)

JAEA Reports

Survey on uranium bearing waste disposal facilities in foreign countries

Saito, Tatsuo; Sakai, Akihiro; Sato, Kazuhiko; Yagi, Naoto; Hata, Haruhi; Fumoto, Hiromichi*; Kawagoshi, Hiroshi; Hasegawa, Makoto

JAEA-Review 2014-021, 30 Pages, 2014/07

JAEA-Review-2014-021.pdf:4.51MB

Japan Atomic Energy Agency surveyed the reference cases for the disposal of uranium bearing waste in low activity concentration as the contents of their own category 2 waste disposal facility for the Research and Development Activities. We reviewed the concepts mentioned in IAEA and ICRP documents, reference cases of uranium bearing waste disposal in selected countries (USA, Canada, UK, France and Sweden), and the disposal styles of long-lived radioactive waste were summarized, and the action items for application to the disposal system of our country was arranged. The disposal facilities in selected countries can be classified into 2 types with the length of performance assessment period for intruder scenario. They are long term assessment type and short term assessment type. It seems that the disposal system construction in category 2 waste disposal is the most realistic since there are many precedence examples of each country. Correspondence of 2 types of these disposal facilities is useful as a reference case.

Journal Articles

Bend-fatigue properties of JPCA and Alloy800H specimens irradiated in a spallation environment

Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Endo, Shinya; Sakuraba, Naotoshi; Miyai, Hiromitsu; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 450(1-3), p.27 - 31, 2014/07

 Times Cited Count:0 Percentile:100(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Operation of electrostatic accelerators

Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Usui, Aya; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Nara, Takayuki; et al.

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 179, 2014/03

Three electrostatic accelerators at TIARA were operated on schedule in fiscal year 2012 except changing its schedule by cancellations of users. The yearly operation time of the 3 MV tandem accelerator, the 400 kV ion implanter and the 3MV single-ended accelerator were in the same levels as the ordinary one, whose operation time totaled to 2,073, 1,847 and 2,389 hours, respectively. The tandem accelerator had no trouble, whereas the ion implanter and the single-ended accelerator stopped by any troubles for one day and four days, respectively. The molecular ion beam of helium hydride was generated by the ion implanter, because the users required irradiation of several cluster ions in order to study the effect of irradiation. As a result, its intensity of beam was 50 nA at 200 kV. The ion beam of tungsten (W) at 15 MeV was accelerated by the tandem accelerator, whose intensity was 20 nA at charge state of 4+, because of the request from a researcher in the field of nuclear fusion.

Journal Articles

Irradiation effect of swift heavy ion for Zr$$_{50}$$Cu$$_{40}$$Al$$_{10}$$ bulk glassy alloy

Onodera, Naoto*; Ishii, Akito*; Ishii, Koji*; Iwase, Akihiro*; Yokoyama, Yoshihiko*; Saito, Yuichi; Ishikawa, Norito; Yabuuchi, Atsushi*; Hori, Fuminobu*

Nuclear Instruments and Methods in Physics Research B, 314, p.122 - 124, 2013/11

 Times Cited Count:2 Percentile:77.1(Instruments & Instrumentation)

It has been reported that heavy ion irradiation causes softening in some cases of Zr-based bulk metallic glass alloys. However, the fundamental mechanisms of such softening have not been clarified yet. In this study, Zr$$_{50}$$Cu$$_{40}$$Al$$_{10}$$ bulk glassy alloys were irradiated with heavy ions of 10 MeV I at room temperature. Positron annihilation measurements have performed before and after irradiation to investigate changes in free volume. We discuss the relationship between the energy loss and local open volume change after 10 MeV I irradiation compared with those obtained for 200 MeV Xe and 5 MeV Al. The energy loss analysis in ion irradiation for the positron lifetime has revealed that the decreasing trend of positron lifetime is well expressed as a function of total electronic energy deposition rather than total elastic energy deposition. It means that the positron lifetime change by the irradiation has a relationship with the inelastic collisions with electrons during heavy ion irradiation.

Journal Articles

Operation of electrostatic accelerators

Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Nara, Takayuki; Kitano, Toshihiko*; et al.

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 173, 2013/01

The three electrostatic accelerators at the TIARA had no mechanical damage when the Tohoku earthquake happened on March 11, 2011. But, they could not be operated during April, due to the influence of planned power outage by TEPCO. These accelerators additionally operated on Saturday for ten days in order to compensate for the lost experiment time. As a result, the yearly operation time had kept the same level as the ordinary one. The ion beam of erbium (Er) with 11.7MeV was accelerated newly by the tandem accelerator, whose intensity was 20nA at charge state of 3+. The sequential generation/irradiation of two different kinds of fullerene ions was achieved at the ion implanter by a mixed powder method without exchange of the Freeman type ion source by the user's request.

Journal Articles

Operation of electrostatic accelerators at TIARA

Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Nara, Takayuki; Kitano, Toshihiko*; et al.

Dai-7-Kai Takasaki Oyo Kenkyu Shimpojiumu Yoshishu, P. 119, 2012/10

The three electrostatic accelerators at TIARA had no damage when the Tohoku earthquake happened on March 11, 2011. But, they could not be operated until end of April, due to the influence of planned power outage and keep out into the controlled area for radiation. These accelerators additionally operated on Saturday for twelve days in order to compensate for the lost experiment time. Therefore, the yearly operation time had kept the same level as the ordinary one. The tandem accelerator has stopped leakage of the SF$$_{6}$$ gas from the base flange on the tank by the Viton gasket of rectangular cross section at the new type.

Journal Articles

Current status of electrostatic accelerators at TIARA

Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Kitano, Toshihiko*; Takayama, Terumitsu*; Orimo, Takao*; Kanai, Shinji*; Aoki, Yuki*; Yamada, Naoto*; et al.

Dai-25-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.64 - 66, 2012/07

The three electrostatic accelerators at the TIARA had no damage when the Tohoku earthquake happened on March 11, 2011. But, they could not be operated until end of April, due to the influence of planned power outage and keep out into the controlled area for radiation. These accelerators additionally operated on Saturday for twelve days in order to compensate for the lost experiment time. Therefore, the yearly operation time had kept the same level as the ordinary one. The tandem accelerator has stopped leakage of the SF$$_{6}$$ gas from the base flange on the tank by the Viton gasket of rectangular cross section at the new type. The ion implanter could generate two kinds of fullerene ions by a mixed material of ions and a controlled temperature of the oven without exchange of ion source.

Journal Articles

Operation of the electrostatic accelerators

Agematsu, Takashi; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Yokota, Wataru; et al.

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 173, 2012/01

Three electrostatic accelerators of TIARA were operated smoothly in FY 2010, and all the planned experiments were carried out except those canceled by users or the impact of Great East Japan Earthquake on March 11, 2011. On the other hand, Saturday operation for experiments was carried out after October on the Global Nuclear-Human Resource Development Initiative. The yearly operation time of the tandem accelerator, the single-ended accelerator and the ion implanter amounted to 2116, 2367 and 1800 hours, respectively, which were similar to those of usual years. Regarding the single-ended accelerator, the generator in the high-voltage terminal failed and was replaced with new one. A switching magnet was installed for a new branch beam line of the ion implanter. As to the tandem accelerator, In ion was generated and accelerated at intensity of 500 nA.

Journal Articles

Current status of electrostatic accelerators at TIARA

Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Agematsu, Takashi; Kitano, Toshihiko*; Takayama, Terumitsu*; Orimo, Takao*; Kanai, Shinji*; Aoki, Yuki*; et al.

Dai-24-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.125 - 128, 2011/07

The yearly operation time of three electrostatic accelerators at TIARA of Japan Atomic Energy Agency is keeping the same level since 2000, the tandem accelerator, the ion implanter and the single-ended accelerator amounted to about 2000, 1900 and 2500 hours, respectively. Three electrostatic accelerators did not have damage when the Tohoku Earthquake occurred on March 11, 2011. However, these accelerators were not able to operate during the planned power outage by Tokyo Electric Power Company (TEPCO). The tandem accelerator accelerated ion beam of In, which gave intensity of 500nA with stability. Additionally, the ion implanter generated maximum 400nA at ion beam of Gd, which was used in experiments for the users.

Journal Articles

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

 Times Cited Count:7 Percentile:49.49(Physics, Nuclear)

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled $$p+p$$ collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to $$p+p$$ collisions.

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