Fusion of 12C + 24Mg at extreme sub-barrier energies
Fusion of 12C + 24Mg at extreme sub-barrier energies
复制标题
12C 24Mg 在极端亚势垒能量下的聚变
DOI：
10.1088/1361-6471/ac7edd
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
S. Szilner and I. Zanon
中科院分区：
文献类型：
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作者：
G. Montagnoli;A.M. Stefanini;C.L. Jiang;K. Hagino;F. Niola;D. Brugnara;P. Colovic;G. Colucci;L. Corradi;R. Depalo;E. Fioretto;A. Goasduff;G. Pasqualato;F. Scarlassara;S. Szilner and I. Zanon
最近进行了 12 C+ 24 Mg 亚势垒聚变实验。标准耦合通道计算显然高估了低能量横截面，并且有迹象表明天体物理 S 因子与能量的最大值。在目前的工作中，我们在同一系统上进行了进一步的测量，并且我们将激发函数扩展到较低的能量至 σ≃ 4 μb，证实了位阻现象的存在。屏障附近还添加了额外的能量点。与之前的实验结果一致，观察到阻碍能量阈值对应于非常大的横截面。目前的新数据可以更好地定义 S 因子最大值，该最大值可以使用障碍模型或绝热模型的两个参数化来很好地拟合。我们还使用伍兹-撒克逊势进行耦合通道计算。远低于势垒，我们观察到耦合强度降低并趋于消失，实际上一维隧道计算很好地再现了激励函数。需要在稍低的能量下进行进一步精确的横截面测量，以区分绝热模型和阻碍模型。这将为外推到天体物理学感兴趣的系统（如 12 C+ 12 C 和 16 O+ 16 O）提供可靠的指导。
A recent experiment on 12 C+ 24 Mg sub-barrier fusion was performed. Standard coupled-channels calculations clearly over-estimated the low energy cross sections and there was indication of a maximum of the astrophysical S factor vs energy. In the present work further measurements have been performed on the same system, and we extended the excitation function to lower energies down to σ≃ 4 μb, confirming the existence of the hindrance phenomenon. Additional energy points near the barrier were added as well. In agreement with the result of previous experiment, the hindrance energy threshold is observed to correspond to a remarkably large cross section. The present new data allow to better define the S-factor maximum, that is well fitted using two parametrizations of either the hindrance or the adiabatic model. We also performed coupled-channels calculations using a Woods–Saxon potential. Far below the barrier we observe that the coupling strengths decrease and tend to vanish, indeed one-dimensional tunnelling calculations well reproduce the excitation function. Further precise cross section measurements at slightly lower energies are needed to discriminate between the adiabatic and hindrance models. This would give a reliable guidance for the extrapolation to the systems of astrophysical interest, like 12 C+ 12 C and 16 O+ 16 O.