OPPORTUNITIES TO CONSTRAIN ASTROPHYSICAL REACTION RATES FOR THE s-PROCESS VIA DETERMINATION OF THE GROUND-STATE CROSS-SECTIONS
OPPORTUNITIES TO CONSTRAIN ASTROPHYSICAL REACTION RATES FOR THE s-PROCESS VIA DETERMINATION OF THE GROUND-STATE CROSS-SECTIONS
复制标题
通过确定基态截面来限制 s 过程天体物理反应速率的机会
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
R. Plag
中科院分区：
文献类型：
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作者：
T. Rauscher;P. Mohr;I. Dillmann;R. Plag
现代的恒星s-过程核合成模型需要高精度的恒星反应速率。大多数中子俘获截面的s-过程已被测量，并为越来越多的反应所需的精度实现。然而，这并不一定意味着恒星速率受到同样好的约束，因为在实验室中只测量了目标基态的捕获。激发态的捕获可以对已经处于典型s过程温度的恒星速率做出相当大的贡献。我们表明，基态贡献X的恒星速率是相关的措施，以确定反应，或可以很好地受到实验的约束，并将其应用到（n，γ）反应的s-过程。我们进一步表明，通过确定基态截面，速率的不确定性的最大可能减少直接由X给出。给出了X的误差分析，发现X是一个具有小不确定性的鲁棒测度。几个具体的例子（79 Se，95 Zr，121 Sn，187 Os和193 Pt的中子俘获）进行了详细讨论。在s过程路径周围的一组412个中子俘获反应的基态贡献在表中给出。这使得可以识别的反应，可能会更好地约束实验，不能仅通过测量基态横截面（因此需要补充研究）的约束。一般趋势和影响进行了讨论。
Modern models of s-process nucleosynthesis in stars require stellar reaction rates of high precision. Most neutron-capture cross-sections in the s-process have been measured, and for an increasing number of reactions the required precision is achieved. This does not necessarily mean, however, that the stellar rates are constrained equally well, because only the capture of the ground state of a target is measured in the laboratory. Captures of excited states can contribute considerably to stellar rates that are already at typical s-process temperatures. We show that the ground-state contribution X to a stellar rate is the relevant measure to identify reactions that are or could be well constrained by experiments and apply it to (n,γ) reactions in the s-process. We further show that the maximum possible reduction in uncertainty of a rate via determination of the ground-state cross-section is given directly by X. An error analysis of X is presented, and it is found that X is a robust measure with mostly small uncertainties. Several specific examples (neutron capture of 79Se, 95Zr, 121Sn, 187Os, and 193Pt) are discussed in detail. The ground-state contributions for a set of 412 neutron-capture reactions around the s-process path are presented in a table. This allows identification of reactions that may be better constrained by experiments and that cannot be constrained solely by measuring ground-state cross-sections (and thus require supplementary studies). General trends and implications are discussed.