用AMS解决恒星~（62）Ni问题
Solving the stellar 62Ni problem with AMS
摘要：
62，63镍的中子俘获截面的准确知识是至关重要的，因为这两种同位素采取的关键位置，影响整个反应流中的弱s过程高达A=90。到目前为止，还没有关于63 Ni（n，gamma）截面的实验值，直到最近，在恒星温度（kT=30 keV）下，62 Ni（n，gamma）的实验值在12 mb和37 mb之间。后一种差异现在可以通过使用慕尼黑串列加速器的GAMS设置的AMS进行两次激活来解决，这也与最近的飞行时间测量完全一致。在kT=30 keV时得到的（初步）麦克斯韦截面被确定为<sigma>30 keV = 23.4 +/- 4.6 mb。此外，我们已经测量了接近阈值的64 Ni（γ，n）63 Ni截面。在13.5 MeV、11.4 MeV和10.3 MeV下的光活化用位于德累斯顿-罗森多夫研究中心（Forschungszentrum Dresden-Rossendorf）的ELBE加速器进行。在13.5 MeV下激活的样品的第一次AMS测量显示，与非吸烟者预测相比，截面小了2倍以上。
英文摘要：
An accurate knowledge of the neutron capture cross sections of 62,63Ni is crucial since both isotopes take key positions which affect the whole reaction flow in the weak s process up to A=90. No experimental value for the 63Ni(n,gamma) cross section exists so far, and until recently the experimental values for 62Ni(n,gamma) at stellar temperatures (kT=30 keV) ranged between 12 and 37 mb. This latter discrepancy could now be solved by two activations with following AMS using the GAMS setup at the Munich tandem accelerator which are also in perfect agreement with a recent time-of-flight measurement. The resulting (preliminary) Maxwellian cross section at kT=30 keV was determined to be <sigma>30keV = 23.4 +/- 4.6 mb. Additionally, we have measured the 64Ni(gamma,n)63Ni cross section close to threshold. Photoactivations at 13.5 MeV, 11.4 MeV and 10.3 MeV were carried out with the ELBE accelerator at Forschungszentrum Dresden-Rossendorf. A first AMS measurement of the sample activated at 13.5 MeV revealed a cross section smaller by more than a factor of 2 compared to NON-SMOKER predictions.
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