Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Ion-species dependent bystander mutagenic effect on locus in normal human fibroblasts induced by C-, Ne- and Ar-ion microbeams

Suzuki, Masao*; Funayama, Tomoo; Yokota, Yuichiro; Muto, Yasuko*; Suzuki, Michiyo; Ikeda, Hiroko; Hattori, Yuya; Kobayashi, Yasuhiko

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 78, 2015/03

https://doi.org/10.11484/jaea-review-2014-050

We have been studying the radiation-quality dependent bystander cellular effects, such as cell killing, mutation induction and chromosomal damage, using heavy-ion microbeams with different ion species. This year we focused on the ion-species dependent bystander mutagenic effect on locus in normal human fibroblasts. The confluent culture were irradiated using a 256 (1616)-cross-stripe method using C, Ne and Ar microbeam. Gene mutation on locus was detected with 6-thioguanine resistant clones. The mutation frequency in cells irradiated with C-ion microbeams was 6 times higher than that of non-irradiated control cells and of the sample treated with specific inhibitor of gap-junction cell-to-cell communication. On the other hand, no enhanced mutation frequencies were observed in cells irradiated with either Ne- or Ar-ion microbeams. There is clear evidence that the bystander mutagenic effect via gap-junction communication depends on radiation quality.

Responses of the salt chemotaxis learning in mutants to microbeam irradiation

Sakashita, Tetsuya; Suzuki, Michiyo; Hattori, Yuya; Ikeda, Hiroko; Muto, Yasuko*; Yokota, Yuichiro; Funayama, Tomoo; Hamada, Nobuyuki*; Shirai, Kana*; Kobayashi, Yasuhiko

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 74, 2015/03

https://doi.org/10.11484/jaea-review-2014-050

An increasing body of data indicates that ionizing radiation affects the nervous system and alters its function. Recently, we reported that chemotaxis of during the salt chemotaxis learning (SCL), that is conditioned taste aversion to NaCl, was modulated by carbon ion irradiation, i.e. accelerated decrease in chemotaxis to NaCl during the SCL. However, we had no direct evidence for the interaction of ionizing radiation with the central neuronal tissue (nerve ring) in . Microbeam irradiation is useful to analyze direct radiation effects at a cellular or tissue level. Thus, we applied the microbeam irradiation of the nerve ring and examined the effect on the SCL.

Status report on technical development of the JAEA AVF cyclotron facility

Kashiwagi, Hirotsugu; Miyawaki, Nobumasa; Okumura, Susumu; Kurashima, Satoshi; Yoshida, Kenichi; Yuri, Yosuke; Yuyama, Takahiro; Ishizaka, Tomohisa; Ishibori, Ikuo; Nara, Takayuki; et al.

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 157, 2012/01

https://doi.org/10.11484/jaea-review-2011-043

no abstracts in English

Present status of JAEA AVF cyclotron facility

Yuyama, Takahiro; Yuri, Yosuke; Ishizaka, Tomohisa; Kurashima, Satoshi; Ishibori, Ikuo; Okumura, Susumu; Yoshida, Kenichi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Nara, Takayuki; et al.

Proceedings of 19th International Conference on Cyclotrons and their Applications (CYCLOTRONS 2010), p.90 - 92, 2011/12

Status of TIARA facility

Yamada, Keisuke; Nara, Takayuki; Ishibori, Ikuo; Kurashima, Satoshi; Yoshida, Kenichi; Yuyama, Takahiro; Ishizaka, Tomohisa; Agematsu, Takashi; Uno, Sadanori; Chiba, Atsuya; et al.

Proceedings of 8th Annual Meeting of Particle Accelerator Society of Japan (Internet), 3 Pages, 2011/08

http://www.pasj.jp/web_publish/pasj8/proceedings/poster/MOPS012.pdf

no abstracts in English

Status of TIARA facility

Yoshida, Kenichi; Nara, Takayuki; Ishibori, Ikuo; Kurashima, Satoshi; Yuyama, Takahiro; Ishizaka, Tomohisa; Agematsu, Takashi; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; et al.

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.23 - 26, 2010/08

http://www.pasj.jp/web_publish/pasj7/proceedings/FSRP/FSRP07.pdf

no abstracts in English

Development of an apparatus for measuring transverse phase-space acceptance

Kashiwagi, Hirotsugu; Miyawaki, Nobumasa; Okumura, Susumu; Ishibori, Ikuo; Kurashima, Satoshi; Yuri, Yosuke; Ishizaka, Tomohisa; Yuyama, Takahiro; Yoshida, Kenichi; Nara, Takayuki; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.945 - 947, 2010/05

http://accelconf.web.cern.ch/accelconf/IPAC10/papers/mopd103.pdf

Characteristics of beam phase in the JAEA AVF cyclotron

Miyawaki, Nobumasa; Okumura, Susumu; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Yuri, Yosuke; Yuyama, Takahiro; Ishizaka, Tomohisa; Ishibori, Ikuo; Nara, Takayuki; et al.

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.183 - 185, 2010/03

http://www.pasj.jp/web_publish/pasj6/papers/wpbda29.pdf

The characteristics of beam phase (BP) for three of acceleration harmonic modes (H=1, 2, 3) were investigated in the central region of the JAEA AVF cyclotron. Experiments were made to clarify relations of BP to the spatial displacements of ion beam orbits in the radial direction at the phase defining slit (PDS), and also to the initial condition of BP at the exit of the inflector defined by the phase shift of the beam bunching (BB). Some correlation of the BPs to both of the position of PDS and the phase shift of BB were observed in the case of H=1, but no correlation was found in the case of H=2. And in the case of H=3, only correlations of the intensity of the beam phase to them were observed with larger phase width than that in case of H=2. It is expected that optimization of the injection system and the central region of the cyclotron can be made according to these characteristics of BP depending on H, so as to obtain higher transmission of high quality ion beams.

Quick change of ion species of heavy-ion microbeam by cocktail beam acceleration technique with the JAEA AVF cyclotron

Kurashima, Satoshi; Yoshida, Kenichi; Oikawa, Masakazu*; Sato, Takahiro; Miyawaki, Nobumasa; Yuyama, Takahiro; Okumura, Susumu; Kashiwagi, Hirotsugu; Ishibori, Ikuo; Nara, Takayuki; et al.

Nuclear Instruments and Methods in Physics Research B, 267(12-13), p.2024 - 2027, 2009/06

https://doi.org/10.1016/j.nimb.2009.03.083

A heavy-ion microbeam with energy of hundreds of MeV is utilized for research in biotechnology and materials science at the JAEA AVF cyclotron facility. Beam users need microbeams providing a wide range of linear energy transfer (LET). In order to vary LET widely, we have to change the ion species and/or energy. A cocktail beam acceleration technique is frequently used to change the ion species quickly. Ion species and energy can be changed by slightly shifting the acceleration frequency. The cocktail acceleration technique has been applied to microbeam production for quick change of ion species of a microbeam. As a result, we have succeeded to reduce considerably microbeam changing time to within 30 minutes between a 260 MeV Ne and a 520 MeV Ar. No deterioration of a microbeam spot size has been confirmed using a secondary electron microscope image of a copper mesh.