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Kawasuso, Atsuo; Maekawa, Masaki; Fukaya, Yuki; Yabuuchi, Atsushi
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 176, 2011/01
We attempt to produce the 
Ge-Ga radioisotope as a highly spin-polarized positron source. We irradiated 20 MeV or 25 MeV proton beam for 
Ga targets. We confirmed the production of Ge-Ga radioisotopes by a nuclear reaction of Ga(p,2n)Ge. From the magnetic field dependence of two-
self-annihilation intensity of positronium in a fused silica, we determined the spin polarization of emitted positrons to be more than 80% as theoretically predicted using the positron helicity.
Kawasuso, Atsuo; Yabuuchi, Atsushi; Maekawa, Masaki; Hasegawa, Shigehiko*; Zhou, Y.-K.*; Asahi, Hajime*
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 148, 2011/01
Vacancy defects in GaCrN grown by molecular beam epitaxy have been characterized by energy variable positron beam. Both positron lifetime and the Doppler broadening of annihilation ray (DBAR) measurements show that the GaCrN film grown at low 540
C contains vacancy defects. The observed vacancy defects are identified as eight-vacancy clusters. Although the Si doping reduces such vacancy clusters probably due to the occupation of Ga sites, another type of vacancy defects still survives. From the detailed theoretical calculation, the residual vacancy defects are attributable to SiGa-VN complexes.
Shikaze, Yoshiaki; Tanimura, Yoshihiko; Saegusa, Jun; Tsutsumi, Masahiro; Uchida, Yoshiaki*; Yoshizawa, Michio; Harano, Hideki*; Matsumoto, Tetsuro*; Mizuhashi, Kiyoshi
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 158, 2011/01
no abstracts in English
-(Ag,Cs) studied by reflection high-energy positron diffractionFukaya, Yuki; Matsuda, Iwao*; Kawasuso, Atsuo; Ichimiya, Ayahiko*
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 150, 2011/01
no abstracts in English
-B surface by reflection high-energy positron diffractionFukaya, Yuki; Kawasuso, Atsuo; Ichimiya, Ayahiko*
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 151, 2011/01
no abstracts in English
Yabuuchi, Atsushi; Maekawa, Masaki; Kawasuso, Atsuo
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 142, 2011/01
Recently, the SCC propagation model that the vacancy-type defects that accumulate in the crack tip play a role as crack nucleus was proposed. However, there is no information available on the generation or accumulation mechanism of such vacancies around the SCC crack tips. In this study, lattice defect spatial distributions around the SCC crack tip in an austenitic stainless steel have been evaluated probed by positron microbeam. As a result, the increase of S-parameter was observed around the SCC crack. To investigate what type of defect has caused the increase of this S parameter, the -ray energy distribution spectrum obtained from the surrounding of the SCC crack was compared with the spectrum obtained from the tensile test specimen. From the comparison of these two spectra, it can be concluded that plastic deformation induced vacancies caused the increase of S-parameter near the SCC crack.
Yabuuchi, Atsushi; Maekawa, Masaki; Kawasuso, Atsuo; Entani, Shiro; Matsumoto, Yoshihiro; Sakai, Seiji; Yamamoto, Shunya
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 131, 2011/01
Ion implantation technique is expected to be useful in fabrication of diluted magnetic semiconductors (DMS) that require high concentration magnetic atom doping without a secondary phase formation. However, ion implantation surely introduces irradiation-induced vacancies into crystals. Recent calculation studies have suggested a presence of vacancies affect the magnetic properties in DMS. In this study, magnetic ions were implanted into compound semiconductor crystals by using ion implantation. N-type ZnO(0001) crystals were implanted with 380 keV maximum energy Cr
ions to a dose of 1
10
ions/cm
. After ion implantation, isochronal annealing in steps of 30 min/100 C was performed. From the measurement results, irradiation-induced vacancies were annealed out at 900 C. From XRD measurements after annealing at 1100 C, no secondary phase peaks were observed. However, from SQUID measurement, a clear magnetic hysteresis was not observed.
Yokoyama, Akihito; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Agematsu, Takashi
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 175, 2011/01
no abstracts in English
Agematsu, Takashi; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Yokota, Wataru; et al.
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 181, 2011/01
Three electrostatic accelerators of TIARA were operated smoothly in FY 2009, and all the planned experiments were carried out except those canceled by users. The yearly operation time of the tandem accelerator, the single-ended accelerator and the ion implanter amounted to 2100, 2416 and 1866 hours, respectively. Regarding the single-ended accelerator, the radio frequency oscillator of the ion source mounted in high-voltage terminal and the sequencer for control of the SB beam line failed, and they were replaced. The oven controller of Freeman ion source of the ion implanter was renewed. As to the tandem accelerator, Mn ion was successfully generated and accelerated with intensity of 150 nA.
Yokota, Wataru; Sato, Takahiro; Okumura, Susumu; Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Koka, Masashi; Takano, Katsuyoshi; Kamiya, Tomihiro
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 173, 2011/01
Microbeam and single-ion hit of 260 MeV-
Ne
and/or 520 MeV-
Ar
were utilized to irradiate living biological cells for study of radiation biology, semiconductor devices for study of radiation effects such as Single Event Upset and polymer films for study of micro-fabrication in fiscal 2009 at the TIARA cyclotron. Although these beams were generally supplied smoothly, we still have technical matters to improve for better beam quality. One of the major subjects is instability of microbeam, and another is miss hit, no ion hit around a targeted point. The paper describes investigation of the causes of those as well as development of new ion beams to be available for microbeam and single-ion hit.
Nara, Takayuki; Ishibori, Ikuo; Kurashima, Satoshi; Yoshida, Kenichi; Yuyama, Takahiro; Ishizaka, Tomohisa; Okumura, Susumu; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Yuri, Yosuke; et al.
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 180, 2011/01
no abstracts in English
ionsChiba, Atsuya; Saito, Yuichi; Narumi, Kazumasa; Takahashi, Yasuyuki; Yamada, Keisuke; Kaneko, Toshiaki*
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 163, 2011/01
The evaluation of the charge state and charge exchange process of the cluster constituent ions inside solid is extremely important for the clarification of the vicinage effect, because the essential interaction forces such as stopping power, wake force and Coulomb repulsion is strongly correlated to the charge state of individual constituent ions. Therefore, the measurement of the divergence angular distributions classified into the charge-state combination of constituent ions resulting from foil-induced dissociation of 6-MeV C ions was carried out in order to investigate the relationship between the internuclear distance and the charge state of individual constituent ions. We suggests that the final charge-state combination of constituents emerging from the foil depends on the initial internuclear-distance which is fluctuated due to a vibration excitation of C ion.
-ray irradiation facilitiesKaneko, 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 -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 -ray irradiation facilities increased in the field of nuclear facilities, and decreased in the field of materials processing and resource & bio-technology.
Tsuchida, Takashi*; Yamagata, Ryohei; Seito, Hajime; Haruyama, Yasuyuki; Kaneko, Hirohisa; Kashimura, Shinji*
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 22, 2011/01
There are a lot of restrictions of electric installations in a high radiation environment. For example longevity of electric devices would be shortened remarkably in a high radiation environment. It becomes impossible also for lighting equipments to keep an original function under a high radiological environment due to deterioration of insulation resistance of ballasts and luminous flux decrease of lamps, etc. The authors developed radiation-resistant lighting. This research aims to verify those functionality and safety under -ray irradiation conditions.
-ray irradiation facilitiesHaruyama, 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 -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.
Ueki, Yuji; Dafader, N. C.*; Seko, Noriaki; Tamada, Masao
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 45, 2011/01
no abstracts in English
Ueki, Yuji; Mohamed, N. H.*; Seko, Noriaki; Tamada, Masao
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 41, 2011/01
no abstracts in English
Mizote, Norihito*; Katakai, Akio*; Tamada, Masao
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 47, 2011/01
no abstracts in English
Kamiya, Yoshiki*; Shin, S.*; Sabarudin, A.*; Umemura, Tomonari*; Ueki, Yuji; Tamada, Masao
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 42, 2011/01
no abstracts in English
Sugo, Yumi; Taguchi, Mitsumasa; Sasaki, Yuji; Hirota, Koichi; Morita, Yasuji
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 17, 2011/01
