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論文

Determining the $$^{239}$$Np($$n$$,$$f$$) cross section using the surrogate ratio method

Czeszumska, A.*; Angell, C.; Burke, J. T.*; Scielzo, N. D.*; Norman, E. B.*; Austin, R. A. E.*; Boutoux, G.*; Casperson, R. J.*; Chodash, P.*; Hughes, R. O.*; et al.

Physical Review C, 87(3), p.034613_1 - 034613_6, 2013/03

AA2012-0918.pdf:0.85MB

 被引用回数:11 パーセンタイル:64.1(Physics, Nuclear)

Neutron-induced fission cross section data are needed in various fields of applied and basic nuclear science. However, cross sections of short-lived nuclei are difficult to measure directly due to experimental constraints. The first experimental determination of the neutron-induced fission cross section of $$^{239}$$Np at non-thermal energies was performed. The Surrogate Ratio Method (SRM) was employed to indirectly deduce the $$^{239}$$Np($$n$$,$$f$$) cross section. The surrogate reactions used were $$^{236}$$U$$(rm ^3He,p)$$ and $$^{238}$$U$$(rm ^3He,p)$$ with the reference cross section given by the well-known $$^{239}$$Np($$n$$,$$f$$) cross section. The ratio of observed fission reactions resulting from the two formed compound nuclei, $$^{238}$$Np and $$^{240}$$Np, was multiplied by the directly-measured $$^{237}$$Np($$n$$,$$f$$) cross section to determine the$$^{239}$$Np($$n$$,$$f$$) cross section. The $$^{239}$$Np($$n$$,$$f$$) cross section was determined with an uncertainty ranging between 3 - 30% over the energy range of 0.2 - 20 MeV.

論文

Event structure and double helicity asymmetry in jet production from polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 84(1), p.012006_1 - 012006_18, 2011/07

 被引用回数:25 パーセンタイル:72.31(Astronomy & Astrophysics)

重心エネルギー200GeVでの縦偏極陽子陽子衝突からのジェット生成のイベント構造と二重非対称($$A_{LL}$$)について報告する。光子と荷電粒子がPHENIX実験で測定され、イベント構造がPHYTIAイベント生成コードの結果と比較された。再構成されたジェットの生成率は2次までの摂動QCDの計算で十分再現される。測定された$$A_{LL}$$は、一番低い横運動量で-0.0014$$pm$$0.0037、一番高い横運動量で-0.0181$$pm$$0.0282であった。この$$A_{LL}$$の結果を幾つかの$$Delta G(x)$$の分布を仮定した理論予想と比較する。

論文

Identified charged hadron production in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; 秋葉 康之*; Al-Bataineh, H.*; Alexander, J.*; 青木 和也*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06

 被引用回数:156 パーセンタイル:99.42(Physics, Nuclear)

200GeVと62.4GeVでの陽子陽子の中心衝突からの$$pi, K, p$$の横運動量分布及び収量をRHICのPHENIX実験によって測定した。それぞれエネルギーでの逆スロープパラメーター、平均横運動量及び単位rapidityあたりの収量を求め、異なるエネルギーでの他の測定結果と比較する。また$$m_T$$$$x_T$$スケーリングのようなスケーリングについて示して陽子陽子衝突における粒子生成メカニズムについて議論する。さらに測定したスペクトルを二次の摂動QCDの計算と比較する。

論文

Laser ablation of gold; Experiment and atomistic simulation

Starikov, S. V.*; Stegailov, V. V.*; Norman, G. E.*; Fortov, V. E.*; 石野 雅彦; 田中 桃子; 長谷川 登; 錦野 将元; 大場 俊幸*; 海堀 岳史; et al.

JETP Letters, 93(11), p.642 - 647, 2011/04

 被引用回数:23 パーセンタイル:76.19(Physics, Multidisciplinary)

The interaction of radiation of a picosecond X-ray laser (wavelength $$lambda$$ = 13.9 nm) with targets made of a thick gold film has been studied theoretically and experimentally. It has been shown experimentally that the action of individual X-ray laser pulses with a fluence of $$F$$ $${approx}$$ 21 mJ/cm$$^{2}$$ initiates the nanostructuring of the gold surface. Explicitly taking into account the electron subsystem, we have proposed an atomistic model of ablation that makes it possible to adequately described the experimental results. The atomistic simulation involves the ion-ion potential depending on the electron temperature $$T$$$$_{e}$$. The use of such a potential makes it possible to take into account an increase in the pressure in the system with increasing $$T$$$$_{e}$$ and to reveal two laser ablation mechanisms.

論文

Measurement of neutral mesons in $$p$$ + $$p$$ collisions at $$sqrt{s}$$ = 200 GeV and scaling properties of hadron production

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 83(5), p.052004_1 - 052004_26, 2011/03

 被引用回数:149 パーセンタイル:98.49(Astronomy & Astrophysics)

RHIC-PHENIX実験で重心エネルギー200GeVの陽子陽子衝突からの$$K^0_s$$, $$omega$$, $$eta'$$$$phi$$中間子生成の微分断面積を測定した。これらハドロンの横運動量分布のスペクトルの形はたった二つのパラメーター、$$n, T$$、のTsallis分布関数でよく記述できる。これらのパラメーターはそれぞれ高い横運動量と低い横運動量の領域のスペクトルを決めている。これらの分布をフィットして得られた積分された不変断面積はこれまで測定されたデータ及び統計モデルの予言と一致している。

口頭

Splash-melting nano-meter size modification of metal surfaces induced by soft X-ray laser single pulse

石野 雅彦; Faenov, A. Ya.*; 田中 桃子; Pikuz, T.; 保 智己*; 長谷川 登; 錦野 将元; Starikov, S. V.*; Stegailov, V. V.*; Norman, G. E.*; et al.

no journal, , 

Laser ablation has many technological applications in material micro-meter size processing and fabrication of nano-structures. We show experimentally the possibility of the precise nano-meter size surface structuring of metal aluminum (Al) and gold (Au) surfaces induced by ultra low fluencies of pico-second soft X-ray laser (SXRL) single pulse. The spatially coherent SXRL beam was generated from the silver (Ag) plasma mediums using oscillator-amplifier configuration with Ag double targets. The generated SXRL pulse had the wavelength of 13.9 nm and the duration of 7 ps. On Al surface, the formations of conical structures were observed in the shallow features. On Au surface, the ripple-like structures were observed. The atomistic model of surface modifications is developed that reveals the ultra-low threshold fluency values of this process and suggests it as a splash-melting regime. Our results will open new opportunities for nano-meter size processing for metal surfaces.

口頭

Metal surfaces nanomodifications induced by the single and multiple pulse soft X-ray laser beam irradiations

Faenov, A.*; Pikuz, T.; 石野 雅彦; Starikov, S. V.*; Stegailov, V. V.*; Norman, G.*; Fortov, V. E.*; Skobelev, I. Yu.*; 保 智己*; 田中 桃子; et al.

no journal, , 

A systematic experimental study of the surface modifications resulting from the interactions of both single and multiple SXRL pulses in order to confirm the development of the modified structures during multiple shots irradiation. The interactions between single or multiple picosecond soft X-ray laser (SXRL) beam and metal (such as gold (Au), copper (Cu), and aluminum (Al)) surfaces, were investigated. Our results demonstrate that tensile stress created in metals by short X-ray pulse can produce spallative ablation of target even for drastically small X-ray fluencies, which open new opportunities for material nano processing.

口頭

Low-threshold surface modification of metals irradiated by picosecond soft X-ray laser pulses; Observation and modeling

Pikuz, T.; Faenov, A.*; 石野 雅彦; Starikov, S. V.*; Stegailov, V. V.*; Norman, G. E.*; Fortov, V.*; Skobelev, I.*; Inogamov, N. A.*; Zhakhovsky, V. V.*; et al.

no journal, , 

Systematic experimental and theoretical studies of the surface modifications resulting from the interactions of both single and multiple SXRL pulses irradiation of metals have been provided. Developed models show that relatively slow electron-ionic relaxation in such metals results in maintaining of the high electron pressure in the near surface region for several picoseconds, that is sufficiently long for the development of the hydrodynamic response that causes the negative pressure region formation and the nanostructuring of a thin surface layer. Obtained results demonstrate that tensile stress created in metals by short X-ray pulse can produce spallative ablation of target even for drastically small X-ray fluencies, which open new opportunities for material nano processing.

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