Background:] In the heavy ion-induced fusion reactions, cross sections in the sub-barrier region are enhanced than the predictions of the one-dimensional barrier penetration model. This enhancement is often understood by invoking deformation and coupling of the relative motion with low-lying inelastic states of the reaction partners. However, effects of nucleon transfer on fusion below the barrier, especially for the systems having positive Q-value neutron transfer (PQNT) channels, is yet to be disentangled completely. [Purpose:] We study the role of PQNT effect on the sub-barrier fusion of ${}^{18}$O+${}^{116}$Sn system having positive Q value for 2 neutron stripping channel. Also we reflect on the interplay of couplings involved in the system around the Coulomb barrier. [Method:] The fusion excitation function was measured at energies from 11$\%$ below to 46$\%$ above the Coulomb barrier for ${}^{18}$O+${}^{116}$Sn using a recoil mass spectrometer, {viz.} the Heavy-Ion Reaction Analyser (HIRA). Fusion barrier distributions were extracted from the data. Results from the experiment were analyzed within the framework of coupled-channels model. [Results:] Fusion cross sections at energies below the Coulomb barrier showed strong enhancement compared to the predictions of one-dimensional barrier penetration model. The fusion process is influenced by couplings to the collective excitations with coupling to single and two phonons vibrational states of the target and projectile respectively. The inclusion of the 2 neutron channel in the calculation along with the couplings could reproduce the data a bit satisfactorily}. [Conclusions:] The significant role of PQNT in enhancing sub-barrier fusion cross section for the chosen system is not observed. It simply reduced the sub-barrier fusion cross section.} Therefore, a consistent link between PQNT and sub-barrier fusion enhancement could not be established while comparing fusion excitation function from this work with the same from other ${}^{16,18}$O-induced reactions. This clearly points to the need for more experimental as well as theoretical investigation in this field.

中文翻译：

---

中子转移在增强18O + 116Sn中子壁聚变截面中的作用

背景：]在重离子诱导的聚变反应中，亚势垒区的横截面比一维势垒穿透模型的预测要强。通常通过调用变形以及相对运动与反应伙伴的低位无弹性状态耦合来理解这种增强。然而，核子转移对壁垒下方融合的影响，特别是对于具有正Q值中子转移（PQNT）通道的系统，尚未完全消除。[目的：]我们研究了PQNT效应在亚屏障融合中的作用。${}^{\mathrm{18岁}}$O +${}^{116}$对2个中子汽提通道具有正Q值的Sn系统。我们还反思了库仑势垒周围系统中涉及的耦合相互作用。[方法：]在11的能量下测量了融合激发函数$％$ 低于46$％$ 在库仑壁垒上方 ${}^{\mathrm{18岁}}$O +${}^{116}$使用反冲质谱仪{Vivi。}重离子反应分析仪（HIRA）来检测Sn。从数据中提取融合壁垒分布。在耦合通道模型的框架内分析了实验结果。[结果：]与一维势垒穿透模型的预测相比，在库仑势垒以下的能量处的聚变截面表现出明显的增强。融合过程受耦合到集体激励的影响，耦合到目标和弹丸的单声子和两个声子的振动状态。计算中包括2个中子通道以及耦合可以使数据令人满意地再现。[结论：]没有观察到PQNT在增强所选系统的亚壁垒融合截面方面的重要作用。${}^{16，\mathrm{18岁}}$O诱导的反应。显然，这表明需要在该领域进行更多的实验和理论研究。