New insights into sub-barrier fusion of ²⁸Si + ¹⁰⁰Mo

Abstract

Fusion cross sections of the 28Si + 100Mo system have been measured near and below the Coulomb barrier by detecting the evaporation residues at forward angles. The excitation function has an overall smoother trend than what obtained in a previous experiment, and a large discrepancy is found for the lowest-energy region, where we observe a tendency of the S factor to develop a maximum, which would be a clear indication of hindrance. The results have been compared with the theoretical prediction of coupled-channels calculations using a Woods–Saxon nuclear potential, and including the low-energy excitation modes of both nuclei. Good agreement with data is found by including, in the coupling scheme, the three lowest members of the ground state rotational band of the oblate deformed 28Si, and two-phonons of the strong quadrupole vibration of 100Mo. The additional coupling, in a schematic way, of the two-neutron pick-up between ground states (Q-value = +4.86 MeV) has a minor effect on calculated cross sections, and does not essentially improve the data fit. The excitation function of 28Si + 100Mo has been compared with that of (1) the heavier system 60Ni + 100Mo having analogous features, and (2) several near-by 28Si, 32S + Zr, Mo systems with various nuclear structures and transfer Q-values. The role of quadrupole and octupole excitation modes, as well as of transfer channels, in affecting the fusion dynamics, are clarified to some extent. Systematic measurements of fusion barrier distributions and CC calculations properly including transfer couplings, are necessary, in order to shed full light on the influence of the various coupled channels on the fusion cross sections.

Comprehensive analysis of heavy-ion fusion reactions around the Coulomb barrier

“…In heavy ion fusion dynamics, it has been experimentally observed that the fusion excitation functions for the large number of projectile-target combinations were found to be enhanced over the outcomes made via onedimensional barrier penetration model (1-DBPM) and is one of the most common problems in the heavy-ion interactions. This anomalous behaviour of fusion excitation function introduces the importance of multidimensional tunneling [1][2][3][4][5][6][7][8][9][10][11][12][13]. In literature, it has been well established that the nuclear structure degrees of freedom associated with reaction partners such as low-lying surface vibrations, zero-point motion, neck formation, static nuclear deformation, entrance channel mass asymmetry, rotational states and/or nucleon transfer channels affect the fusion process and played an important role to establish favourable conditions for the synthesis of a particular compound nucleus [13][14][15][16][17][18][19][20][21][22].…”

“…Therefore, the current effort is an extension of previous studies that will aid in tracking the role of intrinsic degrees of freedom in the fusion process. According to the literature, the fusion of 12 C+ 92 Zr and 16 O+ 92 Zr reactions was dominated by the coupling to multi-phonon vibrational states of the target nucleus, whereas for the fusion of 28 Si+ 92 Zr and 35 Cl+ 92 Zr reactions, the strong influencesof neutron transfer channels were reported [51]. In literature [10,16,22,[52][53][54][55][56][57][58][59][60][61][62][63], it has been demonstrated that the positive Q-value neutron transfer channels favor the fusion enhancement in sub-barrier energy regions.…”

“…Using the one-dimensional Wong formula [50], the SAGBD model [46][47][48][49] and the coupled channel model [41], theoretical calculations of fusion excitation functions are done for the 12 C+ 92 Zr, 16 O+ 92 Zr, 28 12 C+ 194,198 Pt; 16 O+ 144,148,154 Sm and 17 O+ 144 Sm reactions in the sub-barrier domain. Also, the related barrier distributions data for above mentioned reactions are analyzed by using the SAGBD model.…”

Heavy-Ion Fusion Reaction Calculations: Establishing the Theoretical Frameworks for 111In Radionuclide over the Coupled Channel Model

“…The interaction between heavy ions is simply defined as the interaction of two nuclei moving at a central potential of a short-orbit nuclear interaction and a long-orbit Coulomb repulsive effect [1][2][3]. The fusion reactions of heavy ions have attracted the attention of nuclear physicists, who have subsequently performed theoretical and experimental studies in recent years [4][5][6][7]. This enhancement in attention is owing to the day-by-day increase in heavy-ion accelerator research areas with wide and usable energy intervals.…”

Theoretical Inspecting of ²¹¹At Radionuclide via Coupled-Channel Model for Fusion Reaction of Stable Nuclei

“…Fusion mechanisms of heavy-ion interactions have attracted big attention experimentally and theoretically as they reveal the interaction between the nuclear structure and reaction mechanisms [1][2][3][4]. Fusion processes at energies near the Coulomb barrier can be considered as a multidimensional barrier penetration problem [5][6][7][8].…”