标题： 144Sm(α,n)147Gd反应截面的测量用于研究天体物理能区的α-核子光学势 显示英文标题

标题： Cross section measurement of the 144Sm(alpha,n)147Gd reaction for studying the alpha-nucleus optical potential at astrophysical energies

摘要： 涉及α粒子的核反应在各种天体物理过程中起着重要作用，例如重元素核合成的γ过程。 鲜为人知的低能α-核光学势（AOMP）是估算这些反应速率的关键参数。 通过测量α散射截面以及由α引起的反应可以检验AOMP。 最近以高精度测量了144Sm的低能弹性α散射。 本工作的目的是通过测量144Sm在低能下的（α，n）截面来补充这项工作。 实验数据将用于约束AOMP。 从这个势能可以推导出144Sm(α，γ)148Gd反应速率，且不确定性显著降低。 通过Atomki回旋加速器提供的α束轰击Sm靶研究了144Sm(α，n)147Gd反应。 使用激活法确定了截面。 测量了147Gd反应产物衰变后的γ辐射，使用HPGe探测器。 实验数据在统计模型中进行了分析。 在α能量范围13至20 MeV之间，以1 MeV步长测量了截面，即接近（α，n）阈值以上。 结果与使用各种方法和参数化处理AOMP的统计模型计算进行了比较，两种近期势能得到了极好的一致性。 然而，这些势能无法以相同的准确性再现文献中的144Sm(α，γ)148Gd反应数据。 通过对新的144Sm(α，n)147Gd数据和文献中144Sm(α，γ)148Gd数据的分析得出了AOMP的限制条件。 这些限制条件使得能够以小于两倍的不确定性确定144Sm(α，γ)148Gd反应速率。 显示英文摘要

摘要： Nuclear reactions involving alpha particles play an important role in various astrophysical processes such as the gamma-process of heavy element nucleosynthesis. The poorly known low-energy alpha-nucleus optical (AOMP) potential is a key parameter to estimate the rates of these reactions. The AOMP can be tested by measuring the cross section of alpha-scattering as well as alpha-induced reactions. Low energy elastic alpha-scattering on 144Sm has recently been measured with high precision. The aim of the present work was to complement that work by measuring the (a,n) cross sections on 144Sm at low energies. The experimental data shall be used to constrain the AOMP. From this potential the 144Sm(a,g)148Gd reaction rate can be derived with reduced uncertainties. The 144Sm(a,n)147Gd reaction was studied by bombarding Sm targets with alpha-beams provided by the cyclotron accelerator of Atomki. The cross section was determined using the activation method. The gamma-radiation following the decay of the 147Gd reaction product was measured with a HPGe detector. The experimental data are analyzed within the statistical model. The cross section was measured in the alpha-energy range between 13 and 20 MeV in 1 MeV steps, i.e., from close above the (a,n) threshold. The results were compared with statistical model calculations using various approaches and parametrizations for the AOMP, and excellent agreement was obtained for two recent potentials. However, these potentials cannot reproduce literature data for the 144Sm(a,g)148Gd reaction with the same accuracy. Constraints for the AOMP were derived from an analysis of the new 144Sm(a,n)147Gd data and literature data for 144Sm(a,g)148Gd. These constraints enable a determination of the reaction rate of the 144Sm(a,g)148Gd reaction with significantly reduced uncertainties of less than a factor of two.