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Journal Articles

Electronic stopping power dependence of ion-track size in UO$$_{2}$$ irradiated with heavy ions in the energy range of $$sim$$1MeV/u

Ishikawa, Norito; Sonoda, Takeshi*; Sawabe, Takashi*; Sugai, Hiroyuki*; Sataka, Masao*

Nuclear Instruments and Methods in Physics Research B, 314, p.180 - 184, 2013/11

 Times Cited Count:15 Percentile:18.09(Instruments & Instrumentation)

In order to investigate electronic stopping power dependence of ion-track size in UO$$_{2}$$, ion-tracks in UO$$_{2}$$ irradiated with various ions with the specific energy in the order of 1 MeV/u have been observed by a transmission electron microscope. The ion-tracksize shows monotonic increase as a function of the electronic stopping power. Theion-track size obtained for UO$$_{2}$$ is smaller than that obtained for CeO$$_{2}$$, although these two compounds have same crystallographic structure and similar thermal properties. The ion-track sizes for irradiations with ions having relatively low energy of about1 MeV/u are smaller than those expected from the thermal spike models based on melting temperature criterion. The possible interpretations for the unusually smallion-tracks observed for UO$$_{2}$$ are discussed.

JAEA Reports

Influence of Great East Japan Earthquake on neutron source station in J-PARC

Sakai, Kenji; Sakamoto, Shinichi; Kinoshita, Hidetaka; Seki, Masakazu; Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; Naoe, Takashi; Kasugai, Yoshimi; Tatsumoto, Hideki; et al.

JAEA-Technology 2011-039, 121 Pages, 2012/03

JAEA-Technology-2011-039.pdf:10.87MB

This report investigates the behavior, damage and restoration of a neutron source station of the MLF at the Great East Japan Earthquake and verified the safety design for emergency accidents in the neutron source station. In the MLF, after an occurrence of the Earthquake, strong quakes were detected at the instruments, the external power supply was lost, all of the circulators shut down automatically, and the hydrogen gas was released. The leakages of mercury, hydrogen and radio-activation gases did not occur. While, the quakes made gaps between the shield blocks and ruptured external pipe lines by subsidence around the building. But significant damages to the components were not found though the pressure drop of compressed air lines influenced on a target trolley lock system and so on. These results substantiated the validity of the safety design for emergency accidents in the source station, and suggested several points of improvement.

Journal Articles

Influence of Great East Japan Earthquake on neutron target station in J-PARC

Sakai, Kenji; Futakawa, Masatoshi; Takada, Hiroshi; Sakamoto, Shinichi; Maekawa, Fujio; Kinoshita, Hidetaka; Seki, Masakazu; Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; et al.

Proceedings of 20th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-20) (USB Flash Drive), 6 Pages, 2012/03

This report investigates behaviors and damages of each component in a neutron target station of the MLF at the J-PARC at the time of the Great East Japan Earthquake (GEJE). At the date of the GEJE, in the MLF, strong quakes were detected at several instruments, an external power supply were lost, all of the circulation systems were shut down automatically, and a hydrogen gas was released as planned. Leakage of activation liquids and gases did not occur. While, the quakes made gaps between shield blocks and ruptured external pipe lines for air and water by subsidence. But significant damages on the components of the target station were not found though a loss of compressed air supply affected lock systems with air cylinders and pneumatic operation values. These results substantiated a validity of safety design on the target station for emergency accidents.

Journal Articles

Adhesion improvement of HIVIPP $$^{12}$$C targets on Au backings

Sugai, Isao*; Takeda, Yasuhiro*; Kawakami, Hirokane*; Ota, Naoto*; Makii, Hiroyuki; Miyatake, Hiroari*

Nuclear Instruments and Methods in Physics Research A, 655(1), p.24 - 33, 2011/11

 Times Cited Count:3 Percentile:70.32(Instruments & Instrumentation)

Journal Articles

Measurement of the stripping efficiency for HBC stripper foil in the 3-GeV RCS of J-PARC

Saha, P. K.; Yoshimoto, Masahiro; Hatakeyama, Shuichiro; Hotchi, Hideaki; Harada, Hiroyuki; Yamazaki, Yoshio; Kinsho, Michikazu; Irie, Yoshiro*; Sugai, Isao*

Proceedings of 2nd International Particle Accelerator Conference (IPAC 2011) (Internet), p.3511 - 3513, 2011/09

Journal Articles

Possible long-periodic magnetic structure in SmPb$$_{3}$$

Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko; Amato, A.*; Sugai, Takashi; Haga, Yoshinori; Suzuki, Hiroyuki*

Journal of the Physical Society of Japan, 80(Suppl.A), p.SA075_1 - SA075_3, 2011/07

A series of cubic SmX$$_3$$ (X=In, Sn, Pb) compounds has a $$Gamma_8$$ crystalline-electric-field ground state with various multipolar degrees of freedom. These show phase transitions at low temperatures and a possibility of multipolar ordering has been suggested. However, no microscopic experimental data is available so far and details of the ordered states have not been clarified yet. We performed muon spin relaxation measurements in order to elucidate nature of multipoles in these systems. A breaking of time-reversal symmetry was observed in all the ordered phases in zero applied field, indicating the primary order parameters are magnetic. We also obtained information about the ordered structures from a microscopic point of view.

Journal Articles

Incommensurate-to-commensurate magnetic phase transition in SmIn$$_3$$ observed by muon spin relaxation

Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko; Luetkens, H.*; Sugai, Takashi; Haga, Yoshinori; Suzuki, Hiroyuki*

Journal of the Physical Society of Japan, 80(3), p.033710_1 - 033710_4, 2011/03

 Times Cited Count:4 Percentile:63.18(Physics, Multidisciplinary)

Magnetic susceptibility $$chi$$ and muon spin relaxation ($$mu$$SR) measurements are reported on SmIn$$_3$$ with a $$Gamma_8$$ ground state. Anomalies corresponding to successive phase transitions were observed in $$chi$$ at $$T_{rm I}sim$$16.5 K, $$T_{rm II}sim$$15.1 K, and $$T_{rm III}sim$$14.7 K. A spontaneous local magnetic field was detected below $$T_{rm I}$$ using the $$mu$$SR technique on the contrary to a pure quadrupolar ordering scenario proposed in the phase between $$T_{rm I}$$ and $$T_{rm II}$$. This result clearly indicates that the primary order parameters in all the ordered phases are magnetic. The local field distribution changes at around $$T_{rm II}$$ from a continuous broad one to a sharp one with decreasing temperature, suggesting that an incommensurate to commensurate magnetic phase transition takes place at this temperature. A possible magnetic structure in the ground state and importance of multipolar interactions are discussed.

Journal Articles

Electrical property modifications of In-doped ZnO Films by ion irradiation

Matsunami, Noriaki*; Fukushima, Junichi*; Sataka, Masao; Okayasu, Satoru; Sugai, Hiroyuki; Kakiuchida, Hiroshi*

Nuclear Instruments and Methods in Physics Research B, 268(19), p.3071 - 3075, 2010/10

 Times Cited Count:12 Percentile:31.74(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Beam study results with HBC stripping foils at the 3-GeV RCS in J-PARC

Yoshimoto, Masahiro; Yamazaki, Yoshio; Hayashi, Naoki; Yamamoto, Kazami; Saeki, Riuji; Hotchi, Hideaki; Saha, P. K.; Harada, Hiroyuki; Kawase, Masato; Ishiyama, Tatsuya; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3927 - 3929, 2010/05

The ($underline{H}$)ybrid type thick ($underline{B}$)oron-doped ($underline{C}$)arbon (HBC) stripping foils are installed and used for the beam injection at the 3GeV RCS (Rapid Cycling Synchrotron) in J-PARC (Japan Proton Accelerator Research Complex). Up to now, the performance deterioration of the stripping foils can not be seen after the long beam irradiation for the 120kW user operation and 300kW high power beam demonstration at the RCS. In order to examine the characteristic of the HBC foils, various beam studies were carried out. The beam-irradiated spot at the foil was measured by scanning the foil setting position, the charge exchange efficiency was evaluated with various thickness foils, and the effect of the SiC fibers supporting the foil mounting was checked with different mounting foils. Beam study results obtained with using the HBC foils will be presented. In addition, the trends of outgas from the stripping foils and the deformations of the foils during the beam irradiation will be reported.

Journal Articles

Systematic beam loss study due to the foil scattering at the 3-GeV RCS of J-PARC

Saha, P. K.; Hotchi, Hideaki; Harada, Hiroyuki; Yoshimoto, Masahiro; Yamamoto, Kazami; Yamazaki, Yoshio; Sugai, Isao*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3921 - 3923, 2010/05

The beam loss caused by the nuclear scattering together with the multiple Coulomb scattering at the stripping foil is one main concern of the uncontrolled beam losses in RCS of the J-PARC. In order to have a realistic understanding, a systematic study with both experiment and simulation has been carried out recently. A total of seven targets with different thicknesses were used and the measured beam losses were found to be consistent with the simulation. Such a realistic understanding becomes very useful in order to optimized the size and thickness of the stripping foil in connection with the RCS power upgrade scenario not only with the present injection beam energy of 181 MeV but also for the near future upgrade with 400 MeV.

Journal Articles

Vicinage effect on secondary-electron emission in the forward direction from amorphous carbon foils induced by swift C$$_{2}$$$$^{+}$$ ions

Takahashi, Yasuyuki; Narumi, Kazumasa; Chiba, Atsuya; Saito, Yuichi; Yamada, Keisuke; Ishikawa, Norito; Sugai, Hiroyuki; Maeda, Yoshihito

EPL; A Letters Journal Exploring the Frontiers of Physics, 88(6), p.63001_1 - 63001_6, 2009/12

 Times Cited Count:6 Percentile:55.73(Physics, Multidisciplinary)

C$$_{2}$$$$^{+}$$ and C$$_{1}$$$$^{+}$$ ions with 62.5-250 keV/u were incident on self-supporting amorphous carbon foils of 1.4-150 $$mu$$g/cm$$^{2}$$ (70-7500 ${AA}$). The secondary electrons emitted in the forward direction from a carbon foil were detected by a microchannel-plate detector placed at the exit side of the target. The vicinage effect on the secondary-electron yield was evaluated with the ratio of the secondary-electron yield R$$_{2}$$ = $$gamma$$$$_{2}$$/2$$gamma$$$$_{1}$$, where $$gamma$$$$_{2}$$ and $$gamma$$$$_{1}$$ are the yields induced by the C$$_{2}$$$$^{+}$$ and C$$_{1}$$$$^{+}$$ ion with the same velocity, respectively. For the first time the disappearance of the vicinage effect on the secondary-electron yield from amorphous carbon foils bombarded with 62.5 keV/u C$$_{2}$$$$^{+}$$ ions was observed for thick foils of 61-150 $$mu$$g/cm$$^{2}$$. The internuclear distance between the fragment ions at the exit of the target was evaluated by calculating trajectories of the fragment ions considering the Coulomb explosion. For a 62.5 keV/u C$$_{2}$$$$^{+}$$ ion, we have determined the threshold internuclear distance where the vicinage effect disappears exits between 6 ${AA}$ and 23 ${AA}$. It is expected that the vicinage effect on the energy loss (production process) in this velocity region disappears at the internuclear distance of a few ${AA}$. This result means that the transport or transmission process is important for the appearance of the vicinage effect. Moreover, the threshold internuclear distance depends on the velocity of the ion and increases as the velocity increases. The average charge of the ion increases with increase of the velocity of the ion. These mean that there is a possibility that a charge state plays an important role in the origin of the vicinage effect. In order to account for the experimental results, we discussed two models taking account of two kinds of potentials induced in response to the charge of the fragment ion in the transport process.

Journal Articles

Experimental studies of shielding and irradiation effects at high energy accelerator facilities

Nakashima, Hiroshi; Sakamoto, Yukio; Iwamoto, Yosuke; Matsuda, Norihiro; Kasugai, Yoshimi; Nakane, Yoshihiro; Masukawa, Fumihiro; Mokhov, N.*; Leveling, A.*; Boehnlein, D.*; et al.

Nuclear Technology, 168(2), p.482 - 486, 2009/11

BB2007-3640.pdf:0.22MB

 Times Cited Count:7 Percentile:50.3(Nuclear Science & Technology)

Experimental studies of shielding and radiation effects have been started using 120-GeV proton synchrotron at Fermi National Accelerator Laboratory (FNAL) under collaboration between FNAL and Japan. The first campaign of the experiment was carried out at the Pbar target station and Numi experimental station at FNAL, using antiproton and neutrino production targets irradiated by 120-GeV protons. The generated secondary particles passing through steel, concrete and rock were measured by activation methods as well as by other detectors such as scintillator with a veto counter, phoswich detector and a Bonner ball counter on trial. Preliminary experimental results are presented.

Journal Articles

Diffusion experiment with the accelerated, shorot-lived radioactive beam of $$^{8}$$Li

Jeong, S.-C.*; Sugai, Hiroyuki; Yahagi, Masahito*

Nippon Butsuri Gakkai-Shi, 64(9), p.687 - 691, 2009/09

We have demonstrated a non-destructive and on-line radiotracer method for diffusion studies in lithium ionic conductors, by using, as a tracer, the short-lived alpha-emitting radioisotope of $$^{8}$$Li from TRIAC (Tokai Radioactive Ion Accelerator Complex). The method has been successfully applied to measure the lithium diffusion coefficients in a typical defect-mediated lithium ionic conductor of LiGa, well demonstrating that the method is very effective to measure the diffusion in the micrometer regime per second. Anomalous composition-dependence of Li diffusion coefficients in LiGa was observed. The anomaly was discussed qualitatively in terms of the formation of defect complex and the interaction between the constituent defects. The ordering of the Li vacancies in the Li-deficient LiGa was observed for the first time in terms of the Li diffusion by the present method, and its thermodynamic aspect was discussed.

Journal Articles

On-line diffusion tracing in Li ionic conductors by the short-lived radioactive beam of $$^{8}$$Li

Jeong, S.-C.*; Katayama, Ichiro*; Kawakami, Hirokane*; Watanabe, Yutaka*; Ishiyama, Hironobu*; Imai, Nobuaki*; Hirayama, Yoshikazu*; Miyatake, Hiroari; Sataka, Masao; Sugai, Hiroyuki; et al.

Japanese Journal of Applied Physics, 47(8), p.6413 - 6415, 2008/08

 Times Cited Count:5 Percentile:75.42(Physics, Applied)

A non-destructive and on-line diffusion tracing in Li ionic conductors has been demonstrated. As a tracer, pulsed beam of $$^{8}$$Li was implanted into LiGa. By analyzing the time dependent yield of the $$alpha$$-particles decaying from $$^{8}$$Li, diffusion coefficients were extracted with a high accuracy. The ordering of Li vacancies in the Li-deficient $$beta$$ phase of LiGa was observed for the first time in terms of the Li diffusion.

Journal Articles

Diffusion of $$^{8}$$Li short-lived radiotracer in Li ionic conductors of NaTl-type intermetallic compounds

Sugai, Hiroyuki; Sataka, Masao; Okayasu, Satoru; Ichikawa, Shinichi; Nishio, Katsuhisa; Mitsuoka, Shinichi; Nakanoya, Takamitsu; Osa, Akihiko; Sato, Tetsuya; Hashimoto, Takashi; et al.

Defect and Diffusion Forum, 273-276, p.667 - 672, 2008/00

Journal Articles

X-ray diffuse scattering from carbon-ion-irradiated diamond

Sugai, Hiroyuki; Maeta, Hiroshi*; Matsumoto, Norimasa*; Kato, Teruo; Haruna, Katsuji*; Sataka, Masao; Ono, Fumihisa*

Physica Status Solidi (C), 4(8), p.2963 - 2966, 2007/07

 Times Cited Count:0 Percentile:100

The synthetic semiconductor diamond is potentially one of the best materials for electronic devices in severe environments like high temperature and radiation. We have studied the electrical transport properties of boron-doped synthetic semiconductor diamond and characterized natural and synthetic single crystal diamonds by measurements of the X-ray integrated scattering intensity, lattice parameter and diffuse scattering. The synthetic diamond were irradiated with 100 MeV carbon-ion at Tandem accelerator in JAEA-Tokai. After the irradiation, measurements of lattice parameters X-ray diffuse scattering were made at room temperature. The lattice parameters increased with ion fluence. The scattering intensity of the irradiated synthetic diamond diffuses asymmetrically to form a streak along the [-1 0 0] direction parallel to the reciprocal lattice vector. The result suggests that interstitial atoms and vacancies aggregate to form dislocation loop on the (100) plane.

Journal Articles

Prospect for technologies making fusion reactor attractive

Imai, Tsuyoshi*; Kasugai, Atsushi; Higaki, Hiroyuki*

Heisei-19-Nen Denki Gakkai Zenkoku Taikai Koen Rombunshu, 7, p.S9(24) - S9(26), 2007/03

no abstracts in English

Journal Articles

Charge state evolution of 2MeV/u sulfur ion passing through thin carbon foil

Imai, Makoto*; Sataka, Masao; Kawatsura, Kiyoshi*; Takahiro, Katsumi*; Komaki, Kenichiro*; Shibata, Hiromi*; Sugai, Hiroyuki; Nishio, Katsuhisa

Nuclear Instruments and Methods in Physics Research B, 256(1), p.11 - 15, 2007/03

 Times Cited Count:5 Percentile:57.16(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Diffusion of tritium in intermetallic compound $$beta$$-LiAl; Relation to the defect structure

Sugai, Hiroyuki

Solid State Ionics, 177(39-40), p.3507 - 3512, 2007/01

The diffusion coefficient and its activation energy (116.3 $$pm$$ 11.7 kJ/mol) of tritium in an intermetallic compound $$beta$$-LiAl are determined at temperatures from 700 to 848 K. Though the present result for the diffusion coefficient is almost the same as that reported previously, the present result for the activation energy turns out nearly twice of that (64.9 $$pm$$ 3.8 kJ/mol). The present result for the activation energy is consistent with the systematics that an increase of lithium concentration in Al-Li systems increases the activation energy, but the previous result is not. Furthermore, a consideration of the crystal structure and defect structure suggests that tritium diffuses and is impeded by the attractive interaction with lithium atom at lithium sublattices.

Journal Articles

Diffusion of tritium in intermetallic compound $$beta$$-LiAl; Relation to the defect structure

Sugai, Hiroyuki

Solid State Ionics, 177(39-40), p.3507 - 3512, 2007/01

 Times Cited Count:3 Percentile:80.7(Chemistry, Physical)

The diffusion coefficients and its activation energy (103.7$$pm$$9.5 kJ/mol) for tritium in intermetallic compound $$beta$$-LiAl are determined at temperatures from 699 to 886 K. Though the present result for the diffusion coefficient is almost the same as that reported earlier, the activation energy turns out nearly twice of that (64.9$$pm$$3.8 kJ/mol) reported earlier. On the basis of the crystal structure and defect structure, the large activation energy of this study suggest that tritium diffuses interstitially and is impeded by an attractive interaction with lithium atoms in lithium sublattices.

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