标题： 大质量星体中 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： 我们评估了影响 44Ti 在爆炸核合成中产生的两种主要核反应速率及其不确定性。实验上，我们在 E(α) = 4.13、4.54 和 5.36 MeV 的条件下，利用伽马射线光谱学发展了 40Ca(α,γ)44Ti 反应的厚靶产额。在最高束流能量下，我们还进行了一个与厚靶结果一致的激活测量。从测量得到的产额中，我们发展出了一种恒星反应速率，它比当前的统计模型计算和最近的实验结果要小，这表明在 α 富集冻结场景中 44Ti 的产生量可能更低。特别注意的是，我们评估了由实验和理论截面组合产生的恒星速率的实际不确定性，这是我们重新评估 44Ti(α,p)47V 反应速率的基础。利用这些数据，我们对八个代表近期超新星爆炸模型峰值温度和密度条件的膨胀过程中的 44Ti 合成进行了敏感性调查。我们的结果显示，这两种反应速率的当前不确定性可能导致 44Ti 合成的不确定性与恒星物理不同处理方式所引起的不确定性相当。 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.