Isotopic neon cross sections for a study of neutron balance and temperature during s-process nucleosynthesis
Isotopic neon cross sections for a study of neutron balance and temperature during s-process nucleosynthesis
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用于研究 s 过程核合成过程中中子平衡和温度的同位素氖截面
DOI：
10.1086/160686
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
F. Kaeppeler
中科院分区：
文献类型：
--
作者：
J. Almeida;F. Kaeppeler
s过程的中子源被认为是/sup 22/Ne(..cap alpha.., n)反应，发生在脉动红巨星的He燃烧壳层中。这种周期性的中子辐照导致种子核的中子注量呈指数分布，这可以从观测到的太阳系丰度中推断出来。利用凭经验确定的中子注量分布以及 He 壳层中存在的元素的丰度和横截面，计算出 s 过程中每个核素捕获的中子数量。 /sup 22/Ne 具有参与 CNO 循环的 C、N 和 O 同位素，并且是 He 壳层中最丰富的核素（除了 /sup 4/He 和 /sup 12/C）；因此预计它将成为主要的中子吸收剂。由此，我们测量了三种稳定氖同位素在5--400 keV能量范围内的俘获截面，并确定了30 keV麦克斯韦平均截面，精度优于1 mb；还测量了 5 至 800 keV 之间的总横截面。
The neutron source of the s-process is believed to the /sup 22/Ne(..cap alpha.., n) reaction, taking place in the He-burning shell of a pulsating red giant. Such a periodic neutron irradiation leads to an exponential distribution of neutron fluences for the seed nuclei, which can be deduced from the observed solar system abundances. Using this empirically determined distribution of neutron fluences and the abundances and the cross sections of the elements present in the He shell, the number of neutrons captured by each nuclear species during the s-process has been calculated. The /sup 22/Ne has as progenitors the C, N, and O isotopes involved in the CNO cycle, and is the most abundant nuclear species (apart from /sup 4/He and /sup 12/C) in the He shell; it was therefore anticipated that it would be a major neutron absorber. We have thus measured the capture cross sections of the three stable neon isotopes in the energy range 5--400 keV, and we determined the 30 keV Maxwellian averaged cross sections with an accuracy of better than 1 mb; the total cross sections were also measured, between 5 and 800 keV.