[论文解读] Determination of $^{170,172}$Yb($α,n$)$^{173,175}$Hf reaction cross sections in a stacked-target experiment

Martin Müller, Felix Heim+3 more|arXiv (Cornell University)|Jan 9, 2026

Nuclear physics research studies被引用 0

一句话总结

作者通过分层靶活化法测量了 170Yb(α,n)173Hf 和 172Yb(α,n)175Hf 的截面，使用 Mn 基准进行校验，并将结果与 TALYS α-OMP 预测进行比较，突出显示了能够再现数据的若干 α-光学势（α-OMP）.

ABSTRACT

The ytterbium isotopic chain offers multiple stable isotopes on which cross sections can be measured and insights into the evolution of the $α$ optical-model potential with the neutron-to-proton ratio can be gained. It also includes the $p$ nucleus $^{168}$Yb, the abundance of which is significantly impacted by the $^{164,166}$Yb($α,γ$) reactions. In order to study the $^{170,172}$Yb($α,n$)$^{173,175}$Hf reaction cross sections and compare them with $^{168}$Yb($α,n$)$^{171}$Hf cross sections, that have already been measured, the activation method was used. During irradiation the targets were arranged in stacks of four to reduce the required irradiation time. The average interaction energy inside each ytterbium layer was determined via Geant4 simulations. A manganese layer was used to verify the simulations by comparing the measured $^{55}$Mn($α,(2)n$)$^{57,58}$Co reaction cross sections to previous results. For irradiation the 10 MV FN tandem accelerator located at the University of Cologne was used and the activation measurement was performed utilizing the Cologne Clover Counting setup. For the $^{170}$Yb($α,n$) reaction seven cross sections at center-of-mass energies between 12.7 and 16.5 MeV were measured. For the $^{172}$Yb($α,n$) reaction six cross sections for center-of-mass energies of 13.1 to 16.5 MeV could be determined with an additional upper limit at E$_{c.m.}$ = 12.3 MeV. Comparisons to theoretical models show that state-of-the-art $α$-optical model potentials are able to reproduce the measured cross sections very well. The ratios of ($α, n$) reaction cross sections in the ytterbium isotopic chain can be accurately reproduced as well.

研究动机与目标

• 约束与 p 过程反应相关的 α-核光学势（OMPs）。
• 获得 170Yb(α,n)173Hf 和 172Yb(α,n)175Hf 的实验截面以测试 Hauser-Feshbach 输入。
• 用基准反应和模拟对分层靶法激活方法进行验证。
• 通过截面比研究铥铕同位素的 α-OMP 演变。

提出的方法

• 使用带铝 backing 的四靶腔分层激活测量并设 Mn 基准层。
• 基于 Geant4 的反应能量与靶厚度不确定性确定；Srim 交叉校验。
• 使用 Cologne Clover Counting 设置进行伽马射线分光，从多条线和背景中提取产额。
• 通过低能量 170Yb 靶的背景减法来分离 175Hf 信号并传播不确定性。
• 在 11–15.7 MeV 范围内对 55Mn(α,2n)57,58Co 参考反应进行归一化与校验。
• 使用 TALYS-1.95 结合多种 α-OMP 模型（Demetriou、Avrigeanu、Mohr、McFadden–Satchler、Koning）计算理论截面并与数据比较。

实验结果

研究问题

• RQ1 手术状态下的 α-OMP 模型是否能够在实验不确定度内再现所测得的 170Yb 和 172Yb α-诱导的 (n) 截面？
• RQ2 通过铥铕同位素的实验确定的截面及其比值如何约束 α-OMP 随中子/质子比的演变？
• RQ3 不同 α-OMP 参数化对预测截面和推断的天体反应速率有何影响？
• RQ4 分层靶法结合 Geant4 能量损失建模是否能够可靠地确定这些反应的相互作用能量与靶厚度不确定性？
• RQ5 在 Yb–Hf 链中，带有选定 α-OMPs 的 TALYS 预测在再现测得截面及其比值方面有多好？

主要发现

• 在 Ecm = 12.7–16.5 MeV 范围内测得 170Yb(α,n)173Hf 的七个截面。
• 在 Ecm = 13.1–16.5 MeV 范围内测得 172Yb(α,n)175Hf 的六个截面，且在 12.3 MeV 有上限。
• 所有测得的截面都被最先进的 α-OMP 输入在理论模型中非常好地再现。
• 跨铥铕同位素的截面比理论可以准确再现；比值有助于识别关键参数敏感性。
• 背景减法将实验灵敏度提升约四倍。
• 基准 55Mn(α,2n)57,58Co 反应验证了激活法与能量损失模拟的有效性。