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Impact of post-nitridation annealing in CO$$_{2}$$ ambient on threshold voltage stability in 4H-SiC metal-oxide-semiconductor field-effect transistors

細井 卓治*; 大迫 桃恵*; Moges, K.*; 伊藤 滉二*; 木本 恒暢*; 染谷 満*; 岡本 光央*; 吉越 章隆; 志村 考功*; 渡部 平司*

Applied Physics Express, 15(6), p.061003_1 - 061003_5, 2022/06

 被引用回数:1 パーセンタイル:26.82(Physics, Applied)



Comprehensive physical and electrical characterizations of NO nitrided SiO$$_{2}$$/4H-SiC(11$$overline{2}$$0) interfaces

中沼 貴澄*; 岩片 悠*; 渡部 ありさ*; 細井 卓治*; 小林 拓真*; 染谷 満*; 岡本 光央*; 吉越 章隆; 志村 考功*; 渡部 平司*

Japanese Journal of Applied Physics, 61(SC), p.SC1065_1 - SC1065_8, 2022/05

 被引用回数:6 パーセンタイル:83.31(Physics, Applied)



Impact of nitridation on the reliability of 4H-SiC(11$$bar{2}$$0) MOS devices

中沼 貴澄*; 小林 拓真*; 細井 卓治*; 染谷 満*; 岡本 光央*; 吉越 章隆; 志村 考功*; 渡部 平司*

Applied Physics Express, 15(4), p.041002_1 - 041002_4, 2022/04

 被引用回数:2 パーセンタイル:48.21(Physics, Applied)



Superdeformation in $$^{35}$$S

郷 慎太郎*; 井手口 栄治*; 横山 輪*; 小林 幹*; 木佐森 慶一*; 高木 基伸*; 宮 裕之*; 大田 晋輔*; 道正 新一郎*; 下浦 享*; et al.

JPS Conference Proceedings (Internet), 6, p.030005_1 - 030005_4, 2015/06

The high-spin states in $$^{35}$$S were investigated at Tandem-ALTO facility in Institut de Physique Nucl$'e$aire d'Orsay The $$^{26}$$Mg($$^{18}$$O, 2$$alpha$$1n)$$^{35}$$S fusion evaporation reaction was used to populate high-spin states in $$^{35}$$S. The germanium $$gamma$$-ray detector array ORGAM was employed to measure $$gamma$$ rays from high-spin states and charged particles evaporated from the compound nuclei were detected by a segmented silicon detector, Si-Ball. A level scheme for $$^{35}$$S was deduced based on the gamma-gamma-coincidence analysis and $$gamma$$-ray angular correlation analysis. The half-life of the transition in the superdeformed band was estimated by measuring the residual Doppler shift. The deduced half-life shows the large collectivity of the band.


Long-term observation of fog chemistry and estimation of fog water and nitrogen input via fog water deposition at a mountainous site in Hokkaido, Japan

山口 高志*; 堅田 元喜; 野口 泉*; 酒井 茂克*; 渡邊 陽子*; 植松 光夫*; 古谷 浩志*

Atmospheric Research, 151, p.82 - 92, 2015/01

 被引用回数:17 パーセンタイル:48.37(Meteorology & Atmospheric Sciences)

霧沈着による森林地帯への水・窒素供給を定量化するため、2006年から2012年までの植物成長期の日本北部の摩周湖の外輪山における霧化学性および沈着量を調べた。霧水とその粒径分布を自動霧捕集装置と粒径分光計を用いて測定した。過去に行われた酸性霧の暴露実験の結果に基づくと、本研究で観測された霧の酸性度が植物葉の損傷を引き起こすレベルには達していなかった。視程(VIS)と大気中霧水量(LWC)の関係は、夏季と秋季で異なっていた。この関係から経験的にフィッティングしたLWCの予測式と風速および植物パラメータから算出した沈着速度を用いて、この地域の霧沈着量を推定した。植物成長期間の霧による水および窒素沈着量は、それぞれ107-161mmおよび20-41meq m$$^{-2}$$と推定された。


In-beam fissio study at JAEA for heavy element synthesis

西尾 勝久; 池添 博; Hofmann, S.*; Ackermann, D.*; 有友 嘉浩*; Comas, V. F.*; D$"u$llmann, Ch. E.*; Heinz, S.*; Heredia, J. A.*; He${ss}$berger, F. P.*; et al.

AIP Conference Proceedings 1524, p.68 - 72, 2013/04

 被引用回数:0 パーセンタイル:0.04

Fission fragment mass and kinetic energies distributions were measured in the heavy-ion induced reactions using $$^{238}$$U target nucleus at the energies around the Coulomb barrier. We observed strong variation of the fragment mass distribution with incident energy, which was explained by an energy dependence of the probabilities for fusion and quasifission. A calculation based on a fluctuation-dissipation model was carried out to determine the fusion probability in the reactions of $$^{30}$$Si+$$^{238}$$U and $$^{34}$$S+$$^{238}$$U. The fusion probabilities were consistent with those determied from the evaporation residue cross sections for both reactions, showing that in-beam fission measurement and analysis can give a reasonable estimation for the cross sections to produce super-heavy nuclei. We also discss the results for in-beam fission measurement of $$^{48}$$Ca+$$^{238}$$U.


Superdeformed band in asymmetric N $$>$$ Z nucleus, $$^{40}$$Ar and high-spin states in A = 30 $$sim$$ 40 nuclei

井手口 栄治*; 大田 晋輔*; 森川 恒安*; 大島 真澄; 小泉 光生; 藤 暢輔; 木村 敦; 原田 秀郎; 古高 和禎; 中村 詔司; et al.

Progress of Theoretical Physics Supplement, (196), p.427 - 432, 2012/10

A rotational band with five cascade $$gamma$$-ray transitions was newly found in $$^{40}$$Ar. The deduced transition quadrupole moment of $$1.45^{+0.49}_{-0.31}$$ eb has demonstrated this band as having a superdeformed shape of $$beta_2 sim$$ 0.5. The structure of the band was discussed in the framework of cranked Hartree-Fock-Bogoliubov calculations and the assignment of multiparticle-multihole configuration has been made.


Tilted-foil technique for producing a spin-polarized radioactive isotope beam

平山 賀一*; 三原 基嗣*; 渡辺 裕*; Jeong, S. C.*; 宮武 宇也*; 百田 佐多夫*; 橋本 尚志*; 今井 伸明*; 松多 健策*; 石山 博恒*; et al.

European Physical Journal A, 48(5), p.54_1 - 54_10, 2012/05

 被引用回数:2 パーセンタイル:16.94(Physics, Nuclear)

The tilted-foil method for producing spin-polarized radioactive isotope beams has been studied for the application to nuclear physics and materials science, using the radioactive nucleus $$^8$$Li produced at the Tokai Radioactive Ion Accelerator Complex (TRIAC). We successfully produced polarization in a $$^8$$Li beam using 15 thin polystyrene foils fabricated especially for this purpose. A systematic study of the nuclear polarization as a function of the number of foils, beam energy, tilt angles and foil material has been performed, confirming the features of the tilted-foil technique experimentally. The contributions made to the nuclear polarization of $$^8$$Li nuclei by the atomic states was investigated.


GEM-MSTPC; An Active-target type detector in low-pressure He/CO$$_{2}$$ mixed gas

石山 博恒*; 山口 香菜子*; 溝井 浩*; 渡辺 裕*; Das, S. K.*; 橋本 尚志*; 宮武 宇也*; 平山 賀一*; 今井 伸明*; 小柳津 充広*; et al.

Journal of Instrumentation (Internet), 7(3), p.C03036_1 - C03036_14, 2012/03

 被引用回数:7 パーセンタイル:38.12(Instruments & Instrumentation)

不安定核ビームを用いた低エネルギー反応の研究に向けて、低圧力のHe/CO$$_{2}$$混合ガスで動作するガス検出器の開発を行った。高入射率に対応するため、400-$$mu$$m厚のgas electron multiplier(THGEM)を比例計数管として使用することし、最大毎秒10$$^{5}$$個の$$^{12}$$Cビームを用いてテストを行った。テスト結果からTHGEMを用いたガス検出器が高入射率に対応できることを確認した。


Application of multiple prompt $$gamma$$-ray analysis (MPGA) to geochemical and cosmochemical samples

大浦 泰嗣*; 渡部 良*; 海老原 充*; 村上 幸弘*; 藤 暢輔; 木村 敦; 小泉 光生; 古高 和禎; 大島 真澄; 原 かおる; et al.

Journal of Radioanalytical and Nuclear Chemistry, 291(2), p.335 - 339, 2012/02

 被引用回数:4 パーセンタイル:32.53(Chemistry, Analytical)



Investigation of fission properties and evaporation residue measurement in the reactions using $$^{238}$$U target nucleus

西尾 勝久; 池添 博; Hofmann, S.*; Ackermann, D.*; Antalic, S.*; 有友 嘉浩; Comas, V. F.*; D$"u$llmann, Ch. E.*; Gorshkov, A.*; Graeger, R.*; et al.

EPJ Web of Conferences, 17, p.09005_1 - 09005_4, 2011/10

 被引用回数:1 パーセンタイル:47.85

Fission fragment mass distributions after full momentum transfer of the projectile were measured in the reactions using a $$^{238}$$U target nucleus bombarded by $$^{30}$$Si, $$^{31}$$P, $$^{34,36}$$S, $$^{40}$$Ar, $$^{40,48}$$Ca projectiles. We observed a strong variation of the distribution as function of bombarding energy. The results were interpreted by the effects of nuclear deformation of the target nucleus on the competition between fusion and quasifission. The symmetric fission includes fusion-fission, wheres as the asymmetric fission represents quasifission. The fusion probabilities were determined with the help of fluctuation-dissipation model. The estimated evaporation residue cross sections ($$^{263,264}$$Sg and $$^{267,268}$$Hs) produced in $$^{30}$$Si + $$^{238}$$U and $$^{34}$$S+$$^{238}$$U reproduced the experimental data.


Proton resonance elastic scattering in inverse kinematics on the medium heavy nucleus $$^{68}$$Zn

今井 伸明*; 平山 賀一*; 石山 博恒*; Jeong, S.-C.*; 宮武 宇也*; 渡辺 裕*; 牧井 宏之; 光岡 真一; 長江 大輔*; 西中 一朗; et al.

European Physical Journal A, 46(2), p.157 - 160, 2010/11

 被引用回数:3 パーセンタイル:28.96(Physics, Nuclear)

An isobaric analog resonance of $$^{69}$$Zn was studied by the resonance elastic scattering of $$p(^{68}Zn,p)$$ with a 5.5-MeV/nucleon $$^{68}$$Zn beam and a thick polyethylene target. The excitation function of the differential cross section of proton elastic scattering was measured around 0 degrees in the laboratory frame by the thick target inverse kinematics method. The angular momentum, and proton and total widths of the resonance assigned using an $$R$$-matrix calculation are in good agreement with earlier measurements performed using normal kinematics, demonstrating that the thick target inverse kinematics method is a useful tool for studying the single particle structures of neutron-rich nuclei.


Nuclear orientation in the reaction $$^{34}$$S+$$^{238}$$U and synthesis of the new isotope $$^{268}$$Hs

西尾 勝久; Hofmann, S.*; He${ss}$berger, F. P.*; Ackermann, D.*; Antalic, S.*; 有友 嘉浩; Comas, V. F.*; D$"u$llmann, Ch. E.*; Gorshkov, A.*; Graeger, R.*; et al.

Physical Review C, 82(2), p.024611_1 - 024611_9, 2010/08

 被引用回数:77 パーセンタイル:96.02(Physics, Nuclear)

Synthesis of isotopes of the element hassium was studied using the reaction $$^{34}$$S+$$^{238}$$U$$rightarrow$$$$^{272}$$Hs*. At a kinetic energy of 163.0 MeV in the center of mass system we observed one $$alpha$$-decay chain starting at the isotope $$^{267}$$Hs. The cross-section was 1.8$$^{+4.2}_{-1.5}$$pb. At 152.0 MeV one decay of the new isotope $$^{268}$$Hs was observed. It decays with a half-life of 0.38$$^{+1.8}_{-0.17}$$s by 9479$$pm$$16 keV $$alpha$$-particle emission. Spontaneous fission of the daughter nucleus $$^{264}$$Sg was confirmed. The measured cross-section was 0.54$$^{+1.3}_{-0.45}$$pb. In-beam measurements of fission fragment mass distributions were performed to obtain information on the fusion probability at various orientation of the deformed target nucleus. The distributions changed from symmetry to asymmetry when the beam energy was changed from above-barrier to sub-barrier values, indicating orientation effects on fusion and/or quasifission. It was found that the distribution of symmetric mass fragments originates not only from fusion-fission, but has a strong component from quasifission. This result significantly influences the interpretation of data obtained from measurements of symmetric mass distributions with respect to extracting evaporation residue cross-sections.


Barrier distribution of quasi-elastic backward scattering in very heavy reaction systems

光岡 真一; 池添 博; 西尾 勝久; 渡辺 裕*; Jeong, S. C.*; 石山 博恒*; 平山 賀一*; 今井 伸明*; 宮武 宇也

International Journal of Modern Physics E, 19(5&6), p.989 - 996, 2010/07

 被引用回数:0 パーセンタイル:0.01(Physics, Nuclear)

原子力科学研究所タンデムブースター加速器からの重イオンビーム$$^{48}$$Ti, $$^{54}$$Cr, $$^{56}$$Fe, $$^{64}$$Ni, $$^{70}$$Znを薄膜標的$$^{208}$$Pbに照射し、172$$^{circ}$$, 168$$^{circ}$$, 162$$^{circ}$$に後方散乱される準弾性散乱断面積を測定した。入射エネルギーを1.5MeVごとに変えながら測定した励起関数を1階微分することにより、超重元素104-112番元素を合成する冷たい融合反応における融合障壁分布を実験的に導出した。これにより測定された融合障壁は、従来用いられてきた理論値より5-10MeV程度低いことがわかった。また障壁分布の形状は、接近時の励起効果を考慮したチャンネル結合計算結果と良い一致を示すことがわかった。最近、さらに重い反応系$$^{76}$$Ge, $$^{86}$$Kr+$$^{208}$$Pbについても実験を行い、同様の結果が得られた。


Recent progress in the energy recovery linac project in Japan

坂中 章悟*; 明本 光生*; 青戸 智浩*; 荒川 大*; 浅岡 聖二*; 榎本 収志*; 福田 茂樹*; 古川 和朗*; 古屋 貴章*; 芳賀 開一*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05



Effects of nuclear orientation on fusion and fission process for reactions using uranium target nuclei

西尾 勝久; 池添 博; 光岡 真一; 西中 一朗; 牧井 宏之; 渡辺 裕*; 永目 諭一郎; 大槻 勤*; 廣瀬 健太郎*; Hofmann, S.*

AIP Conference Proceedings 1224, p.301 - 310, 2010/04

 被引用回数:5 パーセンタイル:84.89

Results on the measurements of (1) evaporation residue (ER) cross-sections for $$^{30}$$Si, $$^{34}$$S + $$^{238}$$U and of (2) fission fragment mass distributions for $$^{30}$$Si,$$^{34,36}$$S, $$^{40}$$Ar + $$^{238}$$U will be discussed. Measurement of ER cross-section was carried out at GSI by using the velocity filter SHIP. Measurement of fission fragment mass distributions was made by using the JAEA tandem accelerator. In the reaction $$^{30}$$Si + $$^{238}$$U, the ER cross-section for $$^{263}$$Sg(5n) suggested no fusion hindance at above-barrier energy, whereas the one for $$^{264}$$Sg(4n) suggested competition between fusion and quasi-fission at sub-barrier energy. This conclusion is consistent with the measured fragment mass distributions, where the asymmetric fission component associated with quasi-fission appears only at sub-barrier energies. In the reaction of $$^{34}$$S + $$^{238}$$U, the ER cross-sections for $$^{267}$$Hs(5n) and $$^{268}$$Hs(4n, new isotope) suggested fusion hindrance both for above- and sub-barrier energies. With the results of fission fragment mass distributions, it is found that quasi-fission has symmetric fission components when projectile mass is relatively large. We will also discuss the variation of the fragment mass distributions for $$^{30}$$Si,$$^{34,36}$$S, $$^{40}$$Ar + $$^{238}$$U.


Dependence of barrier distribution and fusion-fission process on entrance channel

池添 博; 光岡 真一; 西尾 勝久; 渡辺 裕*; Jeong, S. C.*; 大槻 勤*; 廣瀬 健太郎*

Nuclear Physics A, 834(1-4), p.172c - 175c, 2010/03

 被引用回数:1 パーセンタイル:14.07(Physics, Nuclear)

重い原子核間のクーロン障壁は衝突時に核の励起効果や核子の移行過程が結合して、幅を持って分布する。クーロン障壁分布を$$^{208}$$Pb標的に$$^{48}$$Ti, $$^{54}$$Cr, $$^{56}$$Fe, $$^{64}$$Ni, $$^{70}$$Zn, $$^{76}$$Ge, $$^{86}$$Krを衝突させる反応系で実験的に導出した。その結果、障壁の中心値は簡単なクーロンパラメータでよくスケールされること、分布の幅は$$^{208}$$Pbの8重極振動モードの結合と核子移行反応の結合で説明できること、さらに、導出した障壁は原子核同士の融合障壁とは異なること、がわかった。また、変形核に球形核が衝突する場合、変形核の長軸側での衝突は原子核同士の融合に向かわず、質量の非対象な準核分裂過程に向かうことを、ウラン標的に$$^{30}$$Si, $$^{36}$$S, $$^{40}$$Arを衝突させる反応実験で明らかにした。


Superdeformation in asymmetric $$N$$$$>$$$$Z$$ nucleus $$^{40}$$Ar

井手口 栄治*; 大田 晋輔*; 森川 恒安*; 大島 真澄; 小泉 光生; 藤 暢輔; 木村 敦; 原田 秀郎; 古高 和禎; 中村 詔司; et al.

Physics Letters B, 686(1), p.18 - 22, 2010/03

 被引用回数:32 パーセンタイル:85.83(Astronomy & Astrophysics)

タンデム加速器からの70MeV $$^{18}$$Oビームを$$^{26}$$Mgターゲットに照射し、$$^{40}$$Arの高励起状態を生成した。多重$$gamma$$線検出装置GEMINI-IIを用いて多重$$gamma$$線測定を行い、$$^{40}$$Arにおいて2$$^+$$から12$$^+$$までの5本の$$gamma$$線遷移からなる回転バンドを発見した。得られた遷移四重極モーメント1.45$$pm$$0.15ebはこのバンドが超変形(長軸と短軸の比が2:1に近いラグビーボール型変形)を有することを示唆した。cranked Hartee Fock Bogoliubov計算により、このバンドの性質を調べ、多粒子,多空孔配位であることを確かめた。


Evidence for quasifission in the sub-barrier reaction of $$^{30}$$Si+$$^{238}$$U

西尾 勝久; 池添 博; 西中 一朗; 光岡 真一; 廣瀬 健太郎*; 大槻 勤*; 渡辺 裕*; 有友 嘉浩*; Hofmann, S.*

Physical Review C, 82(4), p.044604_1 - 044604_5, 2010/00

 被引用回数:46 パーセンタイル:91.03(Physics, Nuclear)

Fragment mass distributions for fission after full momentum transfer were measured for the reaction $$^{30}$$Si,+,$$^{238}$$U at bombarding energies around the Coulomb barrier. At energies above the Bass barrier, the mass distributions were Gaussian with mass symmetry. An asymmetric fission channel with mass $$A_{rm L}/A_{rm H}$$,$$approx$$,90$$/$$178 emerged at the sub-barrier energies, where competition between fusion and quasifission was suggested from the measured evaporation residue (ER) cross-section produced in fusion $$^{30}$$Si,+,$$^{238}$$U. We thus conclude the asymmetric channel is attributed to quasifission. The observed mass asymmetry is significantly smaller than those observed in actinide targets bombarded with heavier projectile, which suggests that the system $$^{30}$$Si,+,$$^{238}$$U approaches the shape of compound nucleus before disintegrating as quasifission.


Effects of nuclear orientation on fission fragment mass distributions in the reactions using actinide target nuclei

西尾 勝久; 池添 博; 光岡 真一; 西中 一朗; 牧井 宏之; 渡辺 裕*; 永目 諭一郎; 大槻 勤*; 廣瀬 健太郎*; Hofmann, S.*

AIP Conference Proceedings 1175, p.111 - 118, 2009/10

Fission fragment properties for the reactions involving actinide target nuclei have been investigated at the JAEA tandem facility. The results showed firstly the appearance of new fission channels. The experimental data are useful for the theoretical study to produce super heavy elements. Also the new fission channels suggested the possible production of the neutron rich nuclei by taking advantage of the new fission channels.

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