对$^{185}$W($n,γ$)$^{186}$W截面的新实验约束
New experimental constraint on the $^{185}$W($n,γ$)$^{186}$W cross section
AI总结:
本研究通过钨的光核反应与α散射实验数据,结合核反应程序TALYS,间接约束了$^{185}$W($n,γ$)$^{186}$W的麦克斯韦平均截面,结果低于KADoNiS-1.0推荐值且不确定度更小,对s过程及锇核产额预测有重要意义。
摘要:
在本研究中,我们利用NewSUBARU同步辐射装置产生的准单色光子束,给出了$^{182,183,184}$W($γ,n$)截面的新数据。此外,我们从奥斯陆回旋加速器实验室测量的$^{186}$W($α,α^\rimeγ$)$^{186}$W反应数据中,提取了$^{186}$W的核能级密度和γ射线强度函数。将先前测得的$^{186}$W($γ,n$)截面数据与我们新获得的$^{182,183,184}$W($γ,n$)和($α,α^\rimeγ$)$^{186}$W数据集相结合,我们推导了$1 < E_γ< 6$ MeV和$7 < E_γ< 14$ MeV范围内的$^{186}$W γ射线强度函数。\n我们的数据被用于提取核反应程序\textsf{TALYS}所需的输入量——能级密度和γ射线强度函数,为$^{185}$W($n,γ$)$^{186}$W截面和反应速率提供了间接的实验约束。与KADoNiS-1.0数据库中推荐的麦克斯韦平均截面(MACS)相比,在相关能量范围$k_B T \u2208 [5,100]$ keV内,我们的结果平均更低,并且我们给出的MACS不确定度更小。Bao等人的理论值,以及基于Sonnabend等人的光中子数据得到的实验约束截面,均显著高于我们的结果。Mohr等人给出的更低数值与我们推导的MACS吻合得非常好。我们的新结果可能对s过程,尤其是对$^{186,187}$Os核的s过程产额预测具有重要意义。
英文摘要:
In this work, we present new data on the $^{182,183,184}$W($γ,n$) cross sections, utilizing a quasi-monochromatic photon beam produced at the NewSUBARU synchrotron radiation facility. Further, we have extracted the nuclear level density and $γ$-ray strength function of $^{186}$W from data on the $^{186}$W($α,α^\primeγ$)$^{186}$W reaction measured at the Oslo Cyclotron Laboratory. Combining previous measurements on the $^{186}$W($γ,n$) cross section with our new $^{182,183,184}$W($γ,n$) and ($α,α^\primeγ$)$^{186}$W data sets, we have deduced the $^{186}$W $γ$-ray strength function in the range of $1 < E_γ< 6$ MeV and $7 < E_γ< 14$ MeV. Our data are used to extract the level density and $γ$-ray strength functions needed as input to the nuclear-reaction code \textsf{TALYS}, providing an indirect, experimental constraint for the $^{185}$W($n,γ$)$^{186}$W cross section and reaction rate. Compared to the recommended Maxwellian-averaged cross section (MACS) in the KADoNiS-1.0 data base, our results are on average lower for the relevant energy range $k_B T \in [5,100]$ keV, and we provide a smaller uncertainty for the MACS. The theoretical values of Bao \textit{et al.} and the cross section experimentally constrained on photoneutron data of Sonnabend \textit{et al.} are significantly higher than our result. The lower value by Mohr \textit{et al.} is in very good agreement with our deduced MACS. Our new results could have implications for the $s$-process and in particular the predicted $s$-process production of $^{186,187}$Os nuclei.
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