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Journal Articles

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

 Times Cited Count:30 Percentile:96.87(Astronomy & Astrophysics)

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 $$^{circ}$$C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 $$^{circ}$$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.

Journal Articles

Utilization status of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Uno, Sadanori; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Yamasaki, Shota; Kawashima, Ikuo*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 173, 2016/02

The electron accelerator and the three $$gamma$$-ray irradiation facilities of Takasaki Advanced Radiation Research Institute were operated for various research subjects according to the operation plan in FY 2014. The number of research subjects in FY 2014 decreased at the electron accelerator with operation stop by accelerator trouble, and increased slightly at the $$gamma$$-ray irradiation facilities as compared with FY 2013, and research subjects were 205 and 857, respectively. Among these research subjects, 35 and 172 related to recovery from the Fukushima Daiichi Nuclear disaster, respectively, were performed at the electron accelerator and the $$gamma$$-ray irradiation facilities, respectively.

Journal Articles

Operation of the electron accelerator and the $$^{60}$$Co $$gamma$$-ray irradiation facilities

Uno, Sadanori; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Yamasaki, Shota; Agematsu, Takashi; Kawashima, Ikuo*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 172, 2016/02

This paper reports on the operation status of the $$gamma$$-ray irradiation facilities and the electron accelerator in fiscal 2014 at the Takasaki Advanced Radiation Research Institute of JAEA. The $$gamma$$-ray irradiation facilities were operated smoothly, whereas the electron accelerator stopped for five months because of successive troubles of discharge due to deterioration of equipment over thirty-four years. The annual operation times of the $$gamma$$-ray irradiation facilities of the first, second and food buildings were 19,907, 13,831 and 7,293 hours, respectively, and that of the electron accelerator was 746 hours. The $$gamma$$-ray irradiation facilities were replenished with new five sources of 2.22 PBq, and twenty old sources were removed for disposal. The electron accelerator was repaired for each trouble, however, the complete recovery has not yet been achieved.

Journal Articles

Current status of the electron accelerator at TARRI, JAEA

Uno, Sadanori; Hanaya, Hiroaki; Yamasaki, Shota; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Agematsu, Takashi; Kawashima, Ikuo*; Yagi, Norihiko*; Takagi, Masahide*; et al.

Dai-28-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.121 - 123, 2015/12

no abstracts in English

Journal Articles

Large trigonal-field effect on spin-orbit coupled states in a pyrochlore iridate

Uematsu, Daisuke*; Sagayama, Hajime*; Arima, Takahisa*; Ishikawa, Jun*; Nakatsuji, Satoru*; Takagi, Hidenori*; Yoshida, Masahiro*; Mizuki, Junichiro; Ishii, Kenji

Physical Review B, 92(9), p.094405_1 - 094405_6, 2015/09

 Times Cited Count:21 Percentile:65.47(Materials Science, Multidisciplinary)

Journal Articles

Utilization status of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Kawashima, Ikuo*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 183, 2015/03

The electron accelerator and the three $$gamma$$-ray irradiation facilities were operated for various research subjects according to the operation plan in FY 2013. The number of research subjects at the electron accelerator and at the $$gamma$$-ray irradiation facilities kept constant from FY 2012. Among these research subjects, 47 and 91 ones respectively performed at the electron accelerator and the $$gamma$$-ray irradiation facilities were relevant to recovery from the Fukushima Daiichi nuclear disaster.

Journal Articles

Operation of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Kawashima, Ikuo*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 182, 2015/03

The electron accelerator and the $$gamma$$-ray irradiation facility have been operated approximately smoothly. The annual operation time in FY 2013 for the electron accelerator, the first, the second cobalt irradiation facility and food irradiation facility are 1242 h, 18,900 h, 11,804 h and 6,587 h, respectively. Typically repairs were next ones. The SF$$_{6}$$ gas withdrawal system was renewed at the electron accelerator. The 600 m$$^{3}$$ water storage tank was installed to keep pool-water for the cobalt facilities maintenance. New pieces of $$^{60}$$Co sources were purchased and loaded to the first and the second irradiation facility. The maintenance check was done for the food irradiation facility.

Journal Articles

Dependence of structure of polymer side chain on water structure in hydrogels

Sekine, Yurina; Takagi, Hajime*; Sudo, Sayoko*; Kajiwara, Yutaro*; Fukazawa, Hiroshi; Fukazawa, Tomoko*

Polymer, 55(24), p.6320 - 6324, 2014/11

 Times Cited Count:22 Percentile:65.18(Polymer Science)

To investigate the effects of structure of polymer side chains on structure of water in hydrogels, Raman spectra of polyacrylamide (PAA) and poly-$$N$$,$$N$$-dimethylacrylamide (PDMAA) hydrogels were measured. PAA and PDMAA have similar chemical structures, except for the side chain structure. The result shows that the frequency of the OH stretching mode for the PAA hydrogel decreases as the water content decreases, while that for the PDMAA hydrogel increases. We conclude that most of the bound water molecules in the PAA hydrogel form four strong hydrogen bonds with the hydrophilic groups in the side chain of PAA, whereas those in the PDMAA hydrogel form weak hydrogen bonds with surrounding water molecules. The water structure is an important factor governing the physical and chemical properties of gel materials.

Journal Articles

Utilization status of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 181, 2014/03

The electron accelerator and the three $$gamma$$-ray irradiation facilities were operated for various research subjects according to the operation plan in FY 2012. The number of research subjects at the electron accelerator kept constant compared with FY 2011. The number of research subjects at the $$gamma$$-ray irradiation facilities slightly decreased year after year. Of all these research subjects, 14 ones at the electron accelerator and 93 ones at the $$gamma$$-ray irradiation facilities were relevant to the Fukushima Daiichi nuclear disaster.

Journal Articles

Operation of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 180, 2014/03

The electron accelerator and the $$gamma$$-ray irradiation facility have been operated without serious trouble. The annual operation time in FY 2012 for the electron accelerator, the first, the second cobalt irradiation facility and food irradiation facility are 910 h, 15,738 h, 10,537 h and 7,871 h, respectively. Typicaly repairs were next ones. The SF6 gas withdrawal system broke of the accelerator, and there was trouble of mixing in of air. The maintenance check of the first irradiation facility was done. The $$^{60}$$Co ources were purchased and loaded to the first irradiation facility. Fifteen pencil sources of $$^{60}$$Co with length of 30 cm each, twelve ball sources of $$^{60}$$Co and five $$^{137}$$Cs source were disposed of, and they were transferred to Japan Radioisotope Association (JRIA).

Journal Articles

Operation of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 174, 2013/01

The electron accelerator and the $$gamma$$-ray irradiation facility have been operated without serious trouble. The annual operation time in FY 2011 for the electron accelerator, the first, the second cobalt irradiation facility and food irradiation facility are 1,059 h, 18,722 h, 9,976 h and 7,427 h, respectively. Typically repairs were next ones. The beam control circuit trouble and the isolation trouble by mixing in of air into SF$$_{6}$$ gas at electron accelerator were repaired. The maintenance check of the second irradiation facility was done. The $$^{60}$$Co sources were purchased and loaded to the second irradiation facility. Forty five pencil sources of $$^{60}$$Co with length of 30 cm each, eight coin sources of $$^{60}$$Co and the $$gamma$$-ray radiographic apparatus with a $$^{60}$$Co source were disposed to Japan Radioisotope Association (JRIA).

Journal Articles

Utilization of the electron accelerator and the $$gamma$$-ray irradiation facilities

Haruyama, Yasuyuki; Agematsu, Takashi; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 175, 2013/01

The electron accelerator and the three $$gamma$$-ray irradiation facilities were operated for various research subjects according to the operation plan in FY 2011 without serious trouble. The number of research subjects at the electron accelerator increased in the research fields of nuclear facilities and resources & biotechnology, and decreased in the fields of material processing and material for space. The number of research subjects at the $$gamma$$-ray irradiation facilities increased in the fields of material for space and material processing, and decreased in the fields of nuclear facilities and resources & biotechnology. Of all these research subjects, 15 ones at the electron accelerator and 94 ones at the $$gamma$$-ray irradiation facilities were relevant to the Fukushima Daiichi nuclear disaster.

Journal Articles

Operation of the electron accelerator and $$gamma$$-ray irradiation facilities

Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; Kawashima, Ikuo*; et al.

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 174, 2012/01

The electron accelerator and $$gamma$$-ray irradiation facilities have been operated without serious troubles before the earthquake happened in March 11 2011. The electron accelerator and $$gamma$$-ray irradiation facilities were stopped with concern about the earthquake damage, for 13 and 20 days, respectively.

Journal Articles

Utilization of the $$gamma$$-ray irradiation facilities and electron accelerator

Kaneko, Hirohisa; Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; Kawashima, Ikuo*; et al.

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 175, 2012/01

Irradiation facilities and an electron accelerator were operated for various research subjects according to the operation plan in FY 2010 without serious trouble. Utilization was stopped until the end of the fiscal year due to inspection etc., after the earthquake occurred on March 11. The number at $$gamma$$-ray irradiation facilities increased in the field of environment and basic technology, and decreased in the field of material processing and resource & bio-technology. The number of research subjects at the electron accelerator increased in the research fields of material for space, and decreased in the field of material processing and joint use.

Journal Articles

Utilization of electron accelerator and $$gamma$$-ray irradiation facilities

Kaneko, Hirohisa; Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; Kawashima, Ikuo*; Matsuzaki, Shinya*

JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 183, 2011/01

An electron accelerator and three $$gamma$$-ray irradiation facilities were operated for various research subjects according to the operation plan in FY 2009 without serious trouble. The number of experiment subjects at the electron accelerator increased in the research fields of materials for space and heat-resist material, and decreased in the field of basic technology and nuclear facilities. The number at $$gamma$$-ray irradiation facilities increased in the field of nuclear facilities, and decreased in the field of materials processing and resource & bio-technology.

Journal Articles

Operation of electron accelerator and $$gamma$$-ray irradiation facilities

Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; Kawashima, Ikuo*; Matsuzaki, Shinya*

JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 182, 2011/01

The accelerator served mainly for graft-polymerization for new material development, radiation effect study on semiconductors and various experiments of visiting users. The annual operation time of the electron accelerator was 947.9 h. The Co-60 $$gamma$$-ray irradiation facilities consist of three buildings and cover a wide dose-rate range from 0.04 Gy/h to 20 kGy/h with eight irradiation rooms. The first irradiation facility served mainly for radiation-resistance testing of cables used in nuclear power plants. The second irradiation facility (No.6 irradiation room) operated as hourly scheduled. The food irradiation facility served radiation at lower dose rates. The annual operation time for the first, second cobalt irradiation facilities and food irradiation facility was 15,971 h, 12,389 h and 7,681 h respectively.

Journal Articles

Operation of the electron accelerators and $$gamma$$-ray irradiation facilitis

Haruyama, Yasuyuki; Kaneko, Hirohisa; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Kanazawa, Takao; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; Hirai, Toshiyuki*; et al.

JAEA-Review 2009-041, JAEA Takasaki Annual Report 2008, P. 176, 2009/12

no abstracts in English

Journal Articles

Utilization of the electron accelerator and $$gamma$$-ray irradiation facilities

Kaneko, Hirohisa; Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Kanazawa, Takao; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; Hirai, Toshiyuki*; et al.

JAEA-Review 2009-041, JAEA Takasaki Annual Report 2008, P. 177, 2009/12

no abstracts in English

Journal Articles

Operation of the electron accelerators and $$gamma$$-ray irradiation facilities

Kaneko, Hirohisa; Haruyama, Yasuyuki; Haneda, Noriyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Kanazawa, Takao; Kojima, Takuji; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; et al.

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 192, 2008/11

The accelerator served mainly for graft-polymerization for new material development, radiation effect study on semiconductors and various experiments of visiting users. The annual operation time of the electron accelerator is 706.3h. The Co-60 $$gamma$$-ray irradiation facilities consist of three buildings (8 rooms) and cover a wide dose-rate range from 0.04 Gy/h to 20 kGy/h with eight irradiation cells. The annual operation time for the first, second cobalt irradiation facilities and food irradiation facility is 23,433h, 9,010h and 10,631h.

Journal Articles

Utilization of the electron accelerator and $$gamma$$-ray irradiation facilities

Kaneko, Hirohisa; Haruyama, Yasuyuki; Haneda, Noriyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Kanazawa, Takao; Kojima, Takuji; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; et al.

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 193, 2008/11

An electron accelerator and three $$gamma$$-ray irradiation facilities were operated for various research subjects as operation plan in FY 2007 without serious trouble. The number of research subjects for the electron accelerator and $$gamma$$-ray irradiation facilities is 505 and 1174, respectively. The number of experiment subject at the electron accelerator increased in the research fields of environment and nuclear facilities, and decreased in the field of heat resist. Also, the number at $$gamma$$-ray irradiation facilities increased in the field of resource & bio-technology, and decreased in the field of nuclear facilities.

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