标题： 大质量星中 44Ti 产生的反应率敏感性及其 40Ca(α,γ)44Ti 厚靶产额测量的含义 显示英文标题

标题： Reaction rate sensitivity of 44Ti production in massive stars and implications of a thick target yield measurement of 40Ca(alpha,gamma)44Ti

摘要： 我们评估了两种主导的核反应率及其不确定性，这些因素会影响爆炸核合成中的 44Ti 生成。实验上，我们利用伽马射线光谱学，在 E(α) = 4.13、4.54 和 5.36 MeV 条件下开发了 40Ca(α,γ)44Ti 反应的厚靶产额。在最高束流能量下，我们也进行了激活测量，其结果与厚靶结果一致。从测量得到的产额中，我们发展了一个恒星反应率，该反应率小于目前统计模型的计算结果和最近的实验结果，这表明在 α 富集冻结情景下 44Ti 的生成可能较低。我们特别关注了由实验和理论截面组合产生的恒星反应率的实际不确定性评估，这是我们重新评估 44Ti(α,p)47V 反应率的基础。利用这些数据，我们对八种膨胀情况下的 44Ti 合成进行了敏感性调查，这些膨胀条件是从一组近期超新星爆炸模型中得出的峰值温度和密度条件。我们的结果显示，这两种反应率当前的不确定性可能导致与恒星物理不同处理方式所引起的不确定性一样大的 44Ti 合成变化。 显示英文摘要

摘要： We evaluate two dominant nuclear reaction rates and their uncertainties that affect 44Ti production in explosive nucleosynthesis. Experimentally we develop thick-target yields for the 40Ca(alpha,gamma)44Ti reaction at E(alpha) = 4.13, 4.54, and 5.36 MeV using gamma-ray spectroscopy. At the highest beam energy, we also performed an activation measurement that agrees with the thick target result. From the measured yields a stellar reaction rate was developed that is smaller than current statistical-model calculations and recent experimental results, which would suggest lower 44Ti production in scenarios for the alpha-rich freeze out. Special attention has been paid to assessing realistic uncertainties of stellar rates produced from a combination of experimental and theoretical cross sections, which we use to develop a re-evaluation of the 44Ti(alpha,p)47V reaction rate. Using these we carry out a sensitivity survey of 44Ti synthesis in eight expansions representing peak temperature and density conditions drawn from a suite of recent supernova explosion models. Our results suggest that the current uncertainty in these two reaction rates could lead to as large an uncertainty in 44Ti synthesis as that produced by different treatments of stellar physics.