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Yan, S. Q.*; Li, X. Y.*; 西尾 勝久; Lugaro, M.*; Li, Z. H.*; 牧井 宏之; Pignatari, M.*; Wang, Y. B.*; Orlandi, R.; 廣瀬 健太郎; et al.
Astrophysical Journal, 919(2), p.84_1 - 84_7, 2021/10
被引用回数:1 パーセンタイル:8.87(Astronomy & Astrophysics)The long-lived Fe (with a half-life of 2.62 Myr) is a crucial diagnostic of active nucleosynthesis in the Milky Way galaxy and in supernovae near the solar system. The neutron-capture reaction Fe(n,)Fe on Fe (half-life=44.5 days) is the key reaction for the production of Fe in massive stars. This reaction cross section has been previously constrained by the Coulomb dissociation experiment, which offered partial constraint on the E1 -ray strength function but a negligible constraint on the M1 and E2 components. In this work, for the first time, we use the surrogate ratio method to experimentally determine the Fe(n,)Fe cross sections in which all the components are included. We derived a Maxwellian-averaged cross section of 27.53.5 mb at = 30 keV and 13.41.7 mb at = 90 keV, roughly 10%-20% higher than previous estimates. We analyzed the impact of our new reaction rates in nucleosynthesis models of massive stars and found that uncertainties in the production of Fe from the Fe(n,)Fe rate are at most 25. We conclude that stellar physics uncertainties now play a major role in the accurate evaluation of the stellar production of Fe.
Yan, S. Q.*; Li, Z. H.*; Wang, Y. B.*; 西尾 勝久; Lugaro, M.*; Karakas, A. I.*; 牧井 宏之; Mohr, P.*; Su, J.*; Li, Y. J.*; et al.
Astrophysical Journal, 848(2), p.98_1 - 98_8, 2017/10
被引用回数:5 パーセンタイル:21.48(Astronomy & Astrophysics)The Zr()Zr reaction cross section is crucial in the modelling of -process nucleosynthesis in asymptotic giant branch stars because it controls the operation of the branching point at the unstable Zr and the subsequent production of Zr. We have carried out the measurement of the Zr(O,O) and Zr(O,O) reactions and obtained the -decay probability ratio of Zr and Zr to determine the Zr()Zr reaction cross sections with the surrogate ratio method. We tested our deduced maxwellian-averaged cross section in stellar models with masses between 2 and 6 and metallicities 0.014 and 0.03. The largest changes - up 80 % variations in Zr - are seen in the models of 3-4 , where the Ne neutron source is mildly activated. The new rate can still provide a match to data from meteoritic stardust silicon carbide grains, provided the maximum mass of the parent stars is below 4 , for a metallicity of 0.03.
Yan, S. Q.*; Li, Z. H.*; Wang, Y. B.*; 西尾 勝久; 牧井 宏之; Su, J.*; Li, Y. J.*; 西中 一朗; 廣瀬 健太郎; Han, Y. L.*; et al.
Physical Review C, 94(1), p.015804_1 - 015804_5, 2016/07
被引用回数:6 パーセンタイル:44.49(Physics, Nuclear)The relative -decay probability ratios of the neutron resonance states in Zr and Zr populated via two neutron transfer reactions, Zr(O,O)Zr and Zr(O,O)Zr, have been measured to test the validity of the surrogate ratio method (SRM) in determining the (n,) reaction cross section. The cross sections of the Zr(n,)Zr reaction are derived from the experimentally obtained ratios and the cross sections of the Zr(n,)Zr reaction in the equivalent neutron energy range of = 0 - 8 MeV. The deduced cross sections of Zr(n,)Zr reaction agree with the directly measured ones in the low-energy region, and with the evaluated ENDF/B-VII.1 data at higher energies of 3 MeV. The agreement supports the concept of the SRM method to indirectly determine the (n,) reaction cross sections.
Annadi, A.*; Zhang, Q.*; Renshaw Wang, X.*; Tuzla, N.*; Gopinadhan, K.*; L, W. M.*; Roy Barman, A.*; Liu, Z. Q.*; Srivastava, A.*; Saha, S.*; et al.
Nature Communications (Internet), 4, p.1838_1 - 1838_7, 2013/05
被引用回数:97 パーセンタイル:94.65(Multidisciplinary Sciences)We report the observation of unexpected conductivity at the LaAlO/SrTiO interface prepared on (110)-oriented SrTiO, with a LaAlO-layer thickness-dependent metal-insulator transition. Density functional theory calculation reveals that electronic reconstruction, and thus conductivity, is still possible at this (110) interface by considering the energetically favourable (110) interface structure, that is, buckled TiO/LaO, in which the polarization discontinuity is still present. The conductivity was further found to be strongly anisotropic along the different crystallographic directions with potential for anisotropic superconductivity and magnetism, leading to possible new physics and applications.
Schaffer, M. J.*; Snipes, J. A.*; Gohil, P.*; de Vries, P.*; Evans, T. E.*; Fenstermacher, M. E.*; Gao, X.*; Garofalo, A. M.*; Gates, D. A.*; Greenfield, C. M.*; et al.
Nuclear Fusion, 51(10), p.103028_1 - 103028_11, 2011/10
被引用回数:35 パーセンタイル:80.59(Physics, Fluids & Plasmas)ITERのテストブランケットモジュールが作ると思われる誤差磁場の影響を調べる実験をDIII-Dにおいて実施した。プラズマ回転とモードロッキング,閉じ込め,LH遷移,ELM安定化,ELMとHモードペデスタル特性,高エネルギー粒子損失等を調べた。実験では、ITERの1つの赤道面ポートを模擬する3つ組のコイルを1セット使用した。その結果、ITERのTBMが作る誤差磁場のためにITERの運転が妨げられるような結果は得られなかった。一番大きな変化はプラズマ回転を減速させるものであり、非共鳴ブレーキング効果によってプラズマ全体の回転が50%程度減少した。密度や閉じ込めへの影響は、回転の影響の1/3程度である。これらの影響は、プラズマ圧力の高いプラズマや回転の低いプラズマで顕著である。それ以外の影響は軽微であった。
Snipes, J. A.*; Schaffer, M. J.*; Gohil, P.*; de Vries, P.*; Fenstermacher, M. E.*; Evans, T. E.*; Gao, X. M.*; Garofalo, A.*; Gates, D. A.*; Greenfield, C. M.*; et al.
no journal, ,
磁性体で作られているITERのテストブランケットモジュール(TBM)が作る誤差磁場がプラズマ運転と性能へ与える影響を調べる実験をDIII-Dで実施した。ポロイダル磁場とトロイダル磁場を作る一組のコイルをプラズマ近傍の水平ポートに設置した。TBMコイルは、トロイダル磁場リップルとの総和で5.7%という局所磁場リップルを作り出すことが可能で、この値は1.3トンのITER用TBMが作る局所磁場リップルの4倍に相当する。実験では、トロイダル回転の減少はリップルに敏感であるが、閉じ込め性能への影響では、3%以上の局所磁場リップルで15-18%の減少、1.7%以下では影響はほとんど見られないことがわかった。