The hindrances in the $n\alpha$-nucleus-induced fusion reactions at deep subbarrier energies are investigated by using the coupled-channels model. Inspired by the microscopic Pauli-blocking effects of $\alpha$-cluster decay in radioactive nuclei, a Pauli blocking potential is constructed in the $n\alpha$-nucleus-induced fusion reactions by using a single folding procedure, in which the $n\alpha$ nuclei are assumed to be consisted of $\alpha$ particles. A shallow pocket is formed in the inner part of the potential between two colliding nuclei as compared to the one obtained from the double-folding potential with standard Michigan-3-Yukawa effective nucleon-nucleon interaction. The experimental fusion cross sections are described well for fusion systems ${}^{12}\mathrm{C}+{}^{198}\mathrm{Pt}$, ${}^{16}\mathrm{O}+{}^{208}\mathrm{Pb}$, ${}^{12}\mathrm{C}+{}^{30}\mathrm{Si}$, ${}^{24}\mathrm{Mg}+{}^{30}\mathrm{Si}$, and ${}^{28}\mathrm{Si}+{}^{30}\mathrm{Si}$. At deep subbarrier energies, it is found that this shallow pocket potential reduces the partial fusion cross sections and shields the contributions of high-angular-momentum partial waves to fusion cross sections. In addition, a detailed comparison of fusion processes with different projectiles ${}^{12}\mathrm{C}$, ${}^{24}\mathrm{Mg}$, and ${}^{28}\mathrm{Si}$ on the same target ${}^{30}\mathrm{Si}$ shows the hindrance effect is stronger for heavier projectiles.

• Received 21 May 2020
• Accepted 13 July 2020

DOI:https://doi.org/10.1103/PhysRevC.102.014619