Neutron capture cross sections for the weak s process in massive stars
Neutron capture cross sections for the weak s process in massive stars
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大质量恒星弱 s 过程的中子俘获截面
DOI：
10.1103/physrevc.77.015808
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发表时间：
2008
影响因子：
3.1
通讯作者：
M. Pignatari
中科院分区：
文献类型：
--
作者：
M. Heil;F. Käppeler;E. Uberseder;R. Gallino;M. Pignatari
大质量恒星中的中子俘获核合成在银河系化学演化以及分析非常古老的贫金属晕星的丰度模式方面发挥着重要作用。所谓的弱S过程分量是造成铁和锶之间S丰度的主要原因，它对该质量区的恒星中子俘获截面非常敏感，特别是对Fe周围种子分布附近的同位素非常敏感。在热能为KT=25keV的准静态中子谱中，对{sup 58}Fe，{sup 59}Co，{sup}Ni，{sup 63}和{sup 65}铜进行了激活测量。通过一系列不同实验条件的重复照射，不确定度在3.0%~4.6%之间，比以往的数据准确2~3倍。与以前的测量结果相比，{sup 63，65}铜的测量结果有严重的差异。通过对大质量恒星中对流核He燃烧和对流壳C燃烧的详细模型计算，研究了这些结果的后果。
Neutron capture nucleosynthesis in massive stars plays an important role in galactic chemical evolution as well as for the analysis of abundance patterns in very old metal-poor halo stars. The so-called weak s-process component, which is responsible for most of the s abundances between Fe and Sr, turned out to be very sensitive to the stellar neutron capture cross sections in this mass region and, in particular, of isotopes near the seed distribution around Fe. Activation measurements in a quasistellar neutron spectrum corresponding to a thermal energy of kT=25 keV have been carried out on {sup 58}Fe, {sup 59}Co, {sup 64}Ni, {sup 63}Cu, and {sup 65}Cu. By a series of repeated irradiations with different experimental conditions, uncertainties between 3.0% and 4.6% could be achieved, factors of 2 to 3 more accurate than previous data. Compared to previous measurements, severe discrepancies were found for {sup 63,65}Cu. The consequences of these results have been studied by detailed model calculations for convective core He burning and convective shell C burning in massive stars.