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Journal Articles

Dynamics of radiocaesium within forests in Fukushima; Results and analysis of a model inter-comparison

Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.

Journal of Environmental Radioactivity, 238-239, p.106721_1 - 106721_10, 2021/11

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

This study was aimed at analysing performance of models for radiocesium migration mainly in evergreen coniferous forest in Fukushima, by inter-comparison between models of several research teams. The exercise included two scenarios of countermeasures against the contamination, namely removal of soil surface litter and forest renewal, and a specific konara oak forest scenario in addition to the evergreen forest scenario. All the models reproduced trend of time evolution of radiocesium inventories and concentrations in each of the components in forest such as leaf and organic soil layer. However, the variations between models enlarged in long-term predictions over 50 years after the fallout, meaning continuous field monitoring and model verification/validation is necessary.

JAEA Reports

Development of microbeam formation and single-ion hit technologies at the TIARA cyclotron

Yokota, Wataru; Sato, Takahiro; Kamiya, Tomihiro; Okumura, Susumu; Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Funayama, Tomoo; Sakashita, Tetsuya; et al.

JAEA-Technology 2014-018, 103 Pages, 2014/09

JAEA-Technology-2014-018.pdf:123.66MB

The world's first microbeam focusing technology for heavy ions of hundreds MeV accelerated by a cyclotron has been developed at the TIARA facility in the Takasaki Advanced Radiation Research Institute of the Japan Atomic Energy Agency. The technology enables us to form a microbeam of less than 1 $$mu$$m in diameter and to shoot a specified point on a target by one ion (single-ion hit) with spatial accuracy of microbeam size. In the course of the development, a cyclotron technology to accelerate a small energy-spread beam of hundres MeV, which is necessary for focusing to 1 $$mu$$m, has been developed as well as a beam focusing apparatus, beam size measurement and so forth based on the several-MeV microbeam/single-ion hit system of the TIARA electrostatic accelerators. Applicability of the technologies was examined by actual use in irradiation experiment and the result were fed back to them. This paper reports the process and the results of the development over ten years.

Journal Articles

Establishment of a rearing system of the extremotolerant tardigrade ${it Ramazzottius varieornatus}$; A New model animal for astrobiology

Horikawa, Daiki*; Kunieda, Takekazu*; Abe, Wataru*; Watanabe, Masahiko*; Nakahara, Yuichi*; Yukuhiro, Fumiko*; Sakashita, Tetsuya; Hamada, Nobuyuki*; Wada, Seiichi*; Funayama, Tomoo; et al.

Astrobiology, 8(3), p.549 - 556, 2008/06

 Times Cited Count:70 Percentile:89.07(Astronomy & Astrophysics)

We report the successful rearing of the herbivorous tardigrade, ${it Ramazzottius varieornatus}$, by supplying the green alga ${it Chlorella vulgaris}$ as food. The life span was 35 d, deposited eggs required 5.7 d to hatch, and animals began to deposit eggs 9 d after hatching. The reared individuals of this species had an anhydrobiotic capacity throughout their life cycle in egg, juvenile, and adult stages. Furthermore, the reared adults in an anhydrobiotic state were tolerant of temperatures of 90$$^{circ}$$C and -196$$^{circ}$$C and exposure to 99.8% acetonitrile or irradiation with 4000 Gy $$^{4}$$He ions. Based on their life history traits and tolerance to extreme stresses, ${it R. varieornatus}$ might be a suitable model for astrobiological studies of multicellular organisms.

Oral presentation

Micro-ion-beam applications to life science

Fukuda, Mitsuhiro; Arakawa, Kazuo; Sato, Takahiro; Okumura, Susumu; Saito, Yuichi; Kashiwagi, Hirotsugu; Miyawaki, Nobumasa; Yuri, Yosuke; Ishii, Yasuyuki; Kobayashi, Yasuhiko; et al.

no journal, , 

no abstracts in English

Oral presentation

Focusing microbeam system of JAEA-Takasaki

Funayama, Tomoo; Sakashita, Tetsuya; Oikawa, Masakazu*; Sato, Takahiro; Yokota, Yuichiro; Wada, Seiichi*; Kamiya, Tomihiro; Yokota, Wataru; Kobayashi, Yasuhiko

no journal, , 

We installed new focusing microbeam system at a vertical beam line of AVF cyclotron of TIARA, JAEA. New system is equipped with a quadruplet quadrupole lens system for higher spatial resolution and with an X, Y beam scanner for fast hitting of single ion to micron scaled samples like a biological cell. In vacuum, a microbeam generated by the system had spatial resolution of less than 1 $$mu$$m. The beam was extracted into the atmosphere, and its spatial distribution of ion was observed by irradiating ion track detector, CR39, at just beneath a vacuum window made by Kapton film of 8 $$mu$$m thick. The spatial resolution of beam extracted in air was less than 5 $$mu$$m, indicating that finer microbeam was generated by new focusing microbeam system. New cell targeting system for this microbeam system, which is designed to target and irradiate biological materials more precisely, is currently under development.

Oral presentation

Establishment of rearing system of the extremotolerant tardigrade ${it Ramazzottius varieornatus}$

Wadachi, Hiroki*; Kunieda, Takekazu*; Abe, Wataru*; Nakahara, Yuichi*; Watanabe, Masahiko*; Sakashita, Tetsuya; Hamada, Nobuyuki*; Kobayashi, Yasuhiko; Higashi, Seigo*; Okuda, Takashi*

no journal, , 

We collected some kinds of tardigrade to develop multi-cellular model oraganism for extremotolerant. Among four kinds of collected tardigrade, we found that a tardigrade ${it Ramazzottius varieornatus}$ at Sapporo-city feeded ${it C. vulgaris}$ and could breed. The life-time of ${it R. varieornatus}$ in an artificial culture condition is about 35 days and 5.7 days for hatching. During the whole life-time, one animal laids 8 eggs. In addition, it was observed that ${it R. varieornatus}$ could enter an ametabolic dry state called anhydrobiosis in all stages of life-time. Furthermore, we observed a high surviving-rate even if ${it R. varieornatus}$ exposed in various kinds of extreme environments.

Oral presentation

The Tardigrade ${it Ramazzottius varieornatus}$; A Model for astrobiological studies

Horikawa, Daiki*; Kunieda, Takekazu*; Abe, Wataru*; Koshikawa, Shigeyuki*; Nakahara, Yuichi*; Watanabe, Masahiko*; Iwata, Kenichi*; Sakashita, Tetsuya; Hamada, Nobuyuki*; Higashi, Seigo*; et al.

no journal, , 

We report the first successful rearing of the herbivorous tardigrade, ${it Ramazzottius varieornatus}$, by supplying a green alga ${it Chlorella vulgaris}$ as a food. The reared individuals of this species had an anhydrobiotic capacity throughout their life cycle, from eggs, to juveniles, and to adults. Reared adults, while in an anhydrobiotic state, were tolerant to temperatures -196$$^{circ}$$C and 100$$^{circ}$$C. Furthermore, they were shown to be tolerant to the exposure to 99.8% acetonitrile, 1 GPa of hydrostatic pressure, or 5000 Gy of He ion radiation. We will report the details of these results, along with the description of their life history. Due to the observed tolerance to such extreme environmental conditions, we propose R. varieornatus to be included as a suitable model for astrobiological studies of multicellular organisms.

Oral presentation

Current status of heavy-ion microbeam systems at JAEA-Takasaki

Funayama, Tomoo; Sakashita, Tetsuya; Sato, Takahiro; Fukamoto, Kana; Kurashima, Satoshi; Yokota, Yuichiro; Yokota, Wataru; Kamiya, Tomihiro; Kobayashi, Yasuhiko

no journal, , 

We had developed the heavy-ion microbeam system at TIARA of the Japan Atomic Energy Agency, and utilized for analyzing heavy-ion induced biological effects. Additionally, we have started developing another new focusing microbeam system for carrying out the experiments that cannot be archived by existing collimating microbeam system. The new system can provide finer microbeam by focusing heavy-ion beam from AVF cyclotron using a quadruplet quadrupole lens system. We are now developing a method for irradiating specific region of target sample using the cell targeting station installed last year. The collimating microbeam system was also improved for allowing a novel irradiation means that make a good use of its high fluence characteristics. For that purpose, the cell targeting system of collimating microbeam system was newly designed and updated.

Oral presentation

Heavy-ion microbeam systems and biological studies at JAEA

Sakashita, Tetsuya; Funayama, Tomoo; Sato, Takahiro; Hamada, Nobuyuki*; Fukamoto, Kana; Yokota, Yuichiro; Suzuki, Michiyo; Yokota, Wataru; Kamiya, Tomihiro; Kobayashi, Yasuhiko

no journal, , 

The heavy-ion collimating microbeam system has been developed at JAEA for the radio-surgery technique and radiation biology. Using this system, we can irradiate an exact number of heavy ions at the targeted cell. We show applications of various types of organisms, for example, mammalian cultured cells, a silkworm, a plant and a nematode.

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