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Lattice structure transformation and change in surface hardness of Ni$$_3$$Nb and Ni$$_3$$Ta intermetallic compounds induced by energetic ion beam irradiation

小島 啓*; 吉崎 宥章*; 金野 泰幸*; 千星 聡*; 堀 史説*; 齋藤 勇一; 岡本 芳浩; 岩瀬 彰宏*

Nuclear Instruments and Methods in Physics Research B, 372, p.72 - 77, 2016/04

 被引用回数:6 パーセンタイル:31.55(Instruments & Instrumentation)

複雑な結晶構造を示す金属間化合物Ni$$_3$$Nb and Ni$$_3$$Taを、室温で16MeV Au$$^{5+}$$を使い照射した。X線回折測定の結果、これらの金属間化合物の構造が、照射によって、秩序型構造からアモルファス状態へと変化したことが分かった。照射によるアモルファス化により、ビッカース硬度が上昇した。これらの結果は、以前得られたNi$$_3$$AlおよびNi$$_3$$Vの結果と比較し、試料固有の構造の点から議論された。


Temperature of thermal spikes in amorphous silicon nitride films produced by 1.11 MeV C$$_{60}^{3+}$$ impacts

北山 巧*; 中嶋 薫*; 鈴木 基史*; 鳴海 一雅; 齋藤 勇一; 松田 誠; 左高 正雄*; 辻本 将彦*; 磯田 正二*; 木村 健二*

Nuclear Instruments and Methods in Physics Research B, 354, p.183 - 186, 2015/07

 被引用回数:2 パーセンタイル:74.39(Instruments & Instrumentation)

According to an inelastic-thermal-spike (i-TS) model, which is regarded as the most promising among several models proposed to explain the formation of an ion track, a part of the energy deposited to electrons in a solid by a swift heavy ion is gradually transferred to target atoms via electron-phonon coupling. The temperature of target atoms rises along the ion path and consequently an ion track is formed when the temperature exceeds the melting point. Therefore, the temperature of target atoms along the ion path is regarded as a key parameter for the i-TS model; however, such a spatiotemporally-localized temperature is difficult to measure because the processes involved occur in a very short period ($$<$$ 10$$^{-10}$$ s) and in a very localized area. In this study, the temperature of target atoms along the ion path is estimated experimentally with transmission-electron-microscope (TEM) observation of desorption of Au nanoclusters (the melting point $$sim$$1300 K) on an amorphous Si$$_{3}$$N$$_{4}$$ thin film under 1.1-MeV C$$_{60}^{3+}$$-ion irradiation to the fluence of $$sim$$5$$times$$10$$^{10}$$ ions/cm$$^{2}$$. TEM images show that Au nanoclusters, deposited at the areal density of 1.16$$times$$10$$^{12}$$ particles/cm$$^{2}$$, disappear in a surface area with a diameter of $$sim$$20 nm around each ion track, whose diameter is $$sim$$4 nm, after irradiation. This indicates that the temperature at the film surface rises locally to at least 1300 K by the ion bombardment.


Hardness modification of Al-Mg-Si alloy by using energetic ion beam irradiation

植山 大地*; 齋藤 勇一; 石川 法人; 大村 孝仁*; 千星 聡*; 堀 史説*; 岩瀬 彰宏*

Nuclear Instruments and Methods in Physics Research B, 351, p.1 - 5, 2015/05

 被引用回数:4 パーセンタイル:54.36(Instruments & Instrumentation)

We have irradiated Al-Mg-Si alloy with 5.4 MeV-16 MeV several ion species at room temperature so far, and have found that ion irradiation is a useful tool for controlling the surface hardness for the alloy. In the present study, we tried several experiments as some applications of ion beam irradiation for hardness modifications of the alloy. Main results are as follows; (1) the combination of ion beam irradiation and the subsequent thermal aging are effective for the hardness modification of the alloy, and (2) designated regions and areas of the specimen can be hardened by changing the energy of ion beam and producing the irradiated area and unirradiated area of the surface. Then, we can expand the possibility of the ion beam irradiation as a new process for the three-dimensional hardness modification of Al-Mg-Si alloy.


Monitoring of positron using high-energy gamma camera for proton therapy

山本 誠一*; 歳藤 利行*; 小森 雅孝*; 森下 祐樹*; 奥村 聡*; 山口 充孝; 齋藤 勇一; 河地 有木; 藤巻 秀

Annals of Nuclear Medicine, 29(3), p.268 - 275, 2015/04

 被引用回数:10 パーセンタイル:42.45(Radiology, Nuclear Medicine & Medical Imaging)

In proton therapy, imaging of proton-induced positrons is a useful method to monitor the proton beam distribution after therapy. We developed a small field-of-view gamma camera for high-energy gamma photons and used it for monitoring the proton-induced positron distribution. The gamma camera used 0.85 mm $$times$$ 0.85 mm $$times$$ 10 mm GAGG pixels arranged in 20 $$times$$ 20 matrix to form a scintillator block, which was optically coupled to a 1-inch-square position-sensitive photomultiplier tube. The GAGG detector was encased in a 20-mm-thick container and a pinhole collimator was mounted on its front. The gamma camera had spatial resolution of approximately 6.7 cm and sensitivity of 3.2 $$times$$ 10$$^{-7}$$ at 1.2 m from the collimator surface. The gamma camera was set 1 m from the 35 cm $$times$$ 35 cm $$times$$ 5 cm plastic phantom in the proton therapy treatment room, and proton beams were irradiated to the phantom with two proton energies. For both proton energies, positron distribution in the phantom could be imaged by the gamma camera with 10-min acquisition. The lengths of the range of protons measured from the images were almost identical to the calculation. These results indicate that the developed high-energy gamma camera is useful for imaging positron distributions in proton therapy.


Beam size reduction of a several hundred-keV compact ion microbeam system by improving the extraction condition in an ion source

石井 保行; 大久保 猛; 神谷 富裕; 齋藤 勇一

Nuclear Instruments and Methods in Physics Research B, 348, p.79 - 82, 2015/04

 被引用回数:2 パーセンタイル:74.39(Instruments & Instrumentation)

A hundreds-keV compact ion microbeam system with a three-stage acceleration lens is under development to form an ion beam of several micrometers in diameter. A proton beam of 17$$mu$$m in diameter was formed in the previous study and the smaller beam size could be expected at the lower pressure. In this study, the vacuum system at the extraction space was improved and the relation between the beam size and vacuum pressure was examined by forming hydrogen ion beams at 130 keV. As a result, the beam size of 5.8 $$mu$$m which almost satisfied our present goal was obtained at the achievably lowest pressure (5$$times$$10$$^{-4}$$ Pa).


Effects of irradiation induced Cu clustering on vickers hardness and electrical resistivity of Fe-Cu model alloys

飛田 徹; 中川 将*; 武内 伴照; 鈴木 雅秀; 石川 法人; 知見 康弘; 齋藤 勇一; 曽根田 直樹*; 西田 憲二*; 石野 栞*; et al.

Journal of Nuclear Materials, 452(1-3), p.241 - 247, 2014/09

 被引用回数:12 パーセンタイル:21.02(Materials Science, Multidisciplinary)



Sputtering of SiN films by 540 keV C$$_{60}$$$$^{2+}$$ ions observed using high-resolution Rutherford backscattering spectroscopy

中嶋 薫*; 森田 陽亮*; 北山 巧*; 鈴木 基史*; 鳴海 一雅; 齋藤 勇一; 辻本 将彦*; 磯田 正二*; 藤居 義和*; 木村 健二*

Nuclear Instruments and Methods in Physics Research B, 332, p.117 - 121, 2014/08

 被引用回数:7 パーセンタイル:39.47(Instruments & Instrumentation)

Our previous observation that an impact of sub-MeV C$$_{60}$$ ion makes an ion track in a thin amorphous silicon nitride (a-SiN) film suggests emission of thousands of atoms from the cylindrical region. Sputtering yields of a-SiN films by C$$_{60}$$ ions were evaluated in order to confirm this observation. A-SiN films deposited on Si(001) were irradiated with 540-keV C$$_{60}$$$$^{2+}$$ ions at fluences from 2.5$$times$$10$$^{11}$$ to 1$$times$$10$$^{14}$$ ions/cm$$^{2}$$. The compositional depth profiles of the irradiated samples were measured with high-resolution Rutherford backscattering spectroscopy, and the sputtering yields were estimated at 3900 $$pm$$ 500 N atoms/ion and 1500 $$pm$$ 1000 Si atoms/ion. The sputtering yield of N was two orders of magnitude larger than the elastic sputtering yield by the SRIM code or than the measured electronic sputtering yield of a-SiN by 50-MeV Cu ions previously reported. Such a large sputtering yield cannot be explained either by the elastic sputtering or by the electronic sputtering. However, an estimation of the synergistic effect based on the inelastic thermal spike model roughly explains the observed large sputtering yield, indicating that the synergistic effect of the nuclear and electronic stopping powers plays an important role.


Hardening induced by energetic electron beam for Cu-Ti alloys

植山 大地*; 千星 聡*; 齋藤 勇一; 石川 法人; 西田 憲二*; 曾根田 直樹*; 堀 史説*; 岩瀬 彰宏*

Japanese Journal of Applied Physics, 53(5S1), p.05FC04_1 - 05FC04_5, 2014/05

 被引用回数:4 パーセンタイル:82.21(Physics, Applied)



Magnetic patterning of FeRh thin films by energetic light ion microbeam irradiation

小出 哲也*; 佐藤 隆博; 江夏 昌志; 齋藤 勇一; 神谷 富裕; 大河内 拓雄*; 小嗣 真人*; 木下 豊彦*; 中村 哲也*; 岩瀬 彰宏*; et al.

Japanese Journal of Applied Physics, 53(5S1), p.05FC06_1 - 05FC06_4, 2014/05

 被引用回数:8 パーセンタイル:56.45(Physics, Applied)



Transmission secondary ion mass spectrometry using 5 MeV C$$_{60}$$$$^{+}$$ ions

中嶋 薫*; 永野 賢悟*; 鈴木 基史*; 鳴海 一雅; 齋藤 勇一; 平田 浩一*; 木村 健二*

Applied Physics Letters, 104(11), p.114103_1 - 114103_4, 2014/03

 被引用回数:5 パーセンタイル:70.65(Physics, Applied)

In the secondary ion mass spectrometry (SIMS), use of cluster ions has an advantage of having a high sensitivity of intact large molecular ions over monatomic ions. This paper presents further yield enhancement of the intact biomolecular ions with measuring the secondary ions emitted from a self-supporting thin film in the forward direction, which is the same direction as primary beams. Phenylalanine amino-acid films deposited on self-supporting thin Si$$_{3}$$N$$_{4}$$ films were bombarded with 5-MeV C$$_{60}$$$$^{+}$$ ions. Secondary ions emitted in the forward and backward directions were measured under the bombardments of the SiN and phenylalanine sides, respectively. The yield of intact phenylalanine molecular ions emitted in the forward direction is about one order of magnitude larger than the backward direction, while fragment ions of phenylalanine molecules are suppressed. This suggests a large potential of transmission cluster-ion SIMS for the analysis of biological materials.


Coulomb explosion process in collision of a swift cluster ion with gas target

千葉 敦也; 鳴海 一雅; 山田 圭介; 的場 史朗; 齋藤 勇一

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 167, 2014/03



Status report on technical developments of electrostatic accelerators

山田 圭介; 齋藤 勇一; 石井 保行; 的場 史朗; 千葉 敦也; 横山 彰人; 薄井 絢; 佐藤 隆博; 大久保 猛; 宇野 定則

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 159, 2014/03

TIARA静電加速器において平成24年度に行った技術開発の成果を報告する。タンデム加速器ではクラスターイオン用荷電変換ガスの探索のために、0.24V$$_{B}$$-0.34$$_{B}$$(V$$_{B}$$: Borh velocity)のエネルギー範囲でAuクラスターイオンとHe及びN$$_{2}$$ガスとの衝突によるクラスターイオンの解離断面積を評価した。その結果、解離断面積は実験の範囲ではエネルギー依存性がなく、クラスターサイズ及びガスの種類に依存することがわかった。シングルエンド加速器では、平成23年度までに開発したエミッタンス測定装置を用いて、RFイオン源の引出電圧とエミッタンスの関係を測定した。その結果、1MeVプロトンビームでは、引出電圧が8.4kVのときに最も良いエミッタンスが得られることがわかった。イオン注入装置では、クラスターイオン用ファラデーカップ(FC)の小型化のため、底面に針を敷き詰めることで等価的にアスペクト比を高くしたFCを試作した。本FCを用いてフラーレンイオンの電流測定試験を行った結果、高いアスペクト比を有するFCと同等の測定値が得られたことから、本手法がクラスターイオン用FCの小型化に有用であることがわかった。


Operation of electrostatic accelerators

宇野 定則; 千葉 敦也; 山田 圭介; 横山 彰人; 薄井 絢; 齋藤 勇一; 石井 保行; 佐藤 隆博; 大久保 猛; 奈良 孝幸; et al.

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 179, 2014/03

平成24年度の3台の静電加速器は、ユーザのキャンセルを除きほぼ年間計画に沿って運転された。運転日数はタンデム加速器で171日、イオン注入装置で149日、シングルエンド加速器で168日であり、年間の運転時間は各々2,073時間, 1,847時間, 2,389時間で例年と同水準の運転時間であった。平成21年度から新たに創設され、実施機関として採択された文部科学省補助事業の「先端研究施設共用促進事業」では、11日の利用があった。タンデム加速器では故障による停止はなかったが、イオン注入装置ではイオンの生成不良で1日、シングルエンド加速器ではタンク内のイオン源ガス流量調整バルブの故障により4日停止した。イオン注入装置では、高速クラスターイオン研究開発グループからの要望で水素化ヘリウム(HeH)の分子イオンの生成試験を実施し、ビーム強度は200kVで50nAであった。タンデム加速器では、核融合炉構造材料開発グループからの要望でタングステン(W)イオンの加速試験を行い、15MeV、4価で20nAのビームが得られた。


Development of microwave ion source for industrial applications

高橋 伸明*; 村田 裕彦*; 三堀 仁志*; 桜庭 順二*; 曽我 知洋*; 青木 康*; 加藤 隆典*; 齋藤 勇一; 山田 圭介; 池永 訓昭*; et al.

Review of Scientific Instruments, 85(2), p.02C306_1 - 02C306_3, 2014/02

 被引用回数:2 パーセンタイル:85.43(Instruments & Instrumentation)

Microwave ion source is one of the long-life ion sources, which has been developed for industrial applications such as ion implantation. In this paper, the characteristics of the extracted Ar ion beam from the plasma were studied under various conditions, in terms of magnetic field and pressure of gas. The measured spectra show that, within the experimental condition, most of the beam constituents were singly charged ions, Ar$$^{+}$$ in contrast to ECR ion sources which permits to obtain high current useful for ion implantation. The details of the beam characteristics will be presented corresponding the magnetic field and the pressure of gas.


A Liquid-helium-free superconducting coil system forming a flat minimum-magnetic-field distribution of an electron cyclotron resonance ion source

吉田 健一; 奈良 孝幸; 齋藤 勇一; 横田 渉

Review of Scientific Instruments, 85(2), p.02A917_1 - 02A917_3, 2014/02

 被引用回数:1 パーセンタイル:92.51(Instruments & Instrumentation)

近年のECRイオン源研究では閉じ込め磁場強度の増加だけでなく軸方向のミラー閉じ込め磁場強度B$$_{rm min}$$も多価イオン生成効率に関係すること、さらに従来はクラシカルタイプが一般的であったそのB$$_{rm min}$$形状もフラットタイプの方が多価イオン生成効率が高いことが分かってきた。一方、超電導技術の観点からは、GM冷凍機による伝導冷却型の超電導装置は非常に有利であるが、フラットタイプのB$$_{rm min}$$形状にするには複数のソレノイドコイルが必要になるために熱侵入が多くなり、伝導冷却型では冷凍機が多数必要になってしまう。そこで、フラットB$$_{rm min}$$形状について、低インダクタンスかつ少ない電流導入数で実現できるような磁気回路を考案した。本論文では、このフラットB$$_{rm min}$$に特化した液体ヘリウムを使用しない超電導ECRイオン源の開発について報告する。この磁気回路は、フラットB$$_{rm min}$$の形成を2つの閉じ込め用コイルの他に複数の中心コイルで行った。さらに、電流導入数を少なくするため、その中心コイルをシリーズに繋ぎ、様々なB$$_{rm max}$$でもフラットB$$_{rm min}$$形状となるよう、コイル形状を工夫した。


Production of fullerene ions by combining of plasma sputtering with laser ablation

山田 圭介; 齋藤 勇一; 横田 渉

Review of Scientific Instruments, 85(2), p.02A920_1 - 02A920_3, 2014/02

 被引用回数:1 パーセンタイル:92.51(Instruments & Instrumentation)

A C$$_{60}$$$$^{+}$$ production with combination of plasma sputtering and laser ablation was carried out. A C$$_{60}$$ sample put in an electron cyclotron resonance type ion source was negatively biased and sputtered by argon plasma. A beam current of C$$_{60}$$$$^{+}$$ decreased rapidly and recovered transiently by a single laser shot for ablation of the thin sample surface on the sputtered area. The time variation of beam current with laser shots at few-minute intervals is reported.


Quantitative evaluation of charge-reduction effect in cluster constituent ions passing through a foil

千葉 敦也; 齋藤 勇一; 鳴海 一雅; 山田 圭介; 金子 敏明*

Nuclear Instruments and Methods in Physics Research B, 315, p.81 - 84, 2013/11

 被引用回数:0 パーセンタイル:100(Instruments & Instrumentation)



Time-of-flight secondary ion mass spectrometry with energetic cluster ion impact ionization for highly sensitive chemical structure characterization

平田 浩一*; 齋藤 勇一; 千葉 敦也; 山田 圭介; 鳴海 一雅

Nuclear Instruments and Methods in Physics Research B, 314, p.39 - 42, 2013/11

 被引用回数:3 パーセンタイル:68.05(Instruments & Instrumentation)

Secondary ion mass spectrometry (SIMS) is one of the most powerful tools for surface analysis. Use of a time-of-flight (TOF) mass spectrometry for SIMS is advantageous in efficiently detecting secondary ions at a wider range of mass to charge ratio. We have studied on TOF-SIMS utilizing cluster ions as primary ions. Their Energy dependence to the yield of secondary ions from organic thin films was obtained in the energy range up to MeV order. As a result, it was revealed that the secondary-ion yields for organic material increased with increasing incident cluster energy in the range. This shows that cluster impacts with the energy range of up to MeV order are useful in TOF-SIMS to be applied to the high sensitive analysis of surface for organic materials.


Study on ferromagnetic ordering of FeRh thin films induced by energetic heavy ion irradiation by means of X-ray magnetic circular dichroism

愛甲 一馬*; 唐木 淳志*; 奥田 修一*; 齋藤 勇一; 神谷 富裕; 中村 哲也*; 木下 豊彦*; 岩瀬 彰宏*; 松井 利之*

Nuclear Instruments and Methods in Physics Research B, 314, p.99 - 102, 2013/11

 被引用回数:3 パーセンタイル:68.05(Instruments & Instrumentation)

The ion irradiation induced magnetic state of the FeRh thin films with 10 MeV Iodine ion beam has been investigated by the measurements of a superconducting quantum interference device (SQUID) magnetometer and soft X-ray magnetic circular dichroism (XMCD). It was clearly shown in the magnetization loops by SQUID measurements that the ion irradiation induced ferromagnetic state in the FeRh thin films even below room temperature. This was also confirmed by the XMCD measurements. However ion irradiation fluence dependence on magnetic state at the sample surface measured by XMCD was totally different from that by use of SQUID. Moreover, it was revealed by XMCD sum rule analysis that the ion irradiation induced ferromagnetism of FeRh thin films was mainly dominated by the spin moment.


Irradiation effect of swift heavy ion for Zr$$_{50}$$Cu$$_{40}$$Al$$_{10}$$ bulk glassy alloy

小野寺 直利*; 石井 顕人*; 石井 康嗣*; 岩瀬 彰宏*; 横山 嘉彦*; 齋藤 勇一; 石川 法人; 薮内 敦*; 堀 史説*

Nuclear Instruments and Methods in Physics Research B, 314, p.122 - 124, 2013/11

 被引用回数:2 パーセンタイル:77.33(Instruments & Instrumentation)


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