Role of projectile breakup effects and intrinsic degrees of freedom on fusion dynamics

This article analyzes the fusion dynamics of loosely bound and stable projectiles with Zr-target isotopes within the context of the coupled channel approach and the energy-dependent Woods-Saxon potential model （EDWSP model）. In the case of the 2SSi＋90Zr reaction, the coupling to the inelastic surface excitations results in an adequate description of the observed fusion dynamics while in case of the 2Ssi ＋ 94Zr reaction, the coupling to collective surface vibrational states as well as the neutron （multi-neutron） transfer channel is necessary in the coupled channel calculations to reproduce the below-barrier fusion data. However, the EDWSP model calculation provides an accurate explanation of the fusion data of 2Ssi＋ 90,94Zr reactions in the domain of the Coulomb barrier. In the fusion of the 6Li＋90Zr reaction, the inclusion of the nuclear structure degrees of freedom recovers the observed sub-barrier fusion enhancement but results in suppression of the above barrier fusion data by 34% with respect to the coupled channel calculations. Using EDWSP model calculations, this suppression factor is reduced by 14% and consequently, the above-barrier fusion data of 6Li＋90Zr reaction is suppressed by 20% with reference to the EDWSP model calculations. Such fusion suppression at above-barrier energies can be correlated with the breakupof the projectile （6Li） before reaching the fusion barrier, as a consequence of low binding energy.

Entrance Channel Mass Asymmetry Effects in Sub-Barrier Fusion Dynamics by Using Energy Dependent Woods–Saxon Potential

The present article highlights the inconsistency of static Woods Saxon potential and the applicability of energy dependent Woods Saxon potential to explore the fusion dynamics of ^(48)_(22)Ti+^(58,60,64)_(28)Ni,^(46)_(22)Ti+^(64)_(28)Ti+^(50)_(22)Ti+^(60)_(28)Ni,and^(19)_9F+^(93)_(41)Nb reactions leading to formation of different Sn-isotopes via different entrance channels.Theoretical calculations based upon one-dimensional Wong formula obtained by using static Woods Saxon potential unable to provide proper explanation for sub-barrier fusion enhancement of these projectile-target combinations.However,the predictions of onedimensional Wong formula based upon energy dependent Woods Saxon potential model(EDWSP model) accurately describe the observed fusion dynamics of these systems wherein the significantly larger value of diffuseness parameter ranging from a = 0.85 fm to a = 0.97 fm is required to address the experimental data in whole range of energy.Therefore,the energy dependence in nucleus-nucleus potential simulates the influence of the nuclear structure degrees of freedom of the colliding pairs.

Static versus energy-dependent nucleus–nucleus potential for description of sub-barrier fusion dynamics of _8^(16)O+_(50)^(112,116,120)Sn reactions

The static and energy-dependent nucleus–nucleus potentials are simultaneously used along with the Wong formula for exploration of fusion dynamics of 8^16O＋50^112,116,120Sn reactions. The role of internal structure degrees of freedom of colliding pairs, such as inelastic surface vibrations, are examined within the context of coupled channel calculations performed using the code CCFULL. Theoretical calculations based on the static Woods–Saxon potential along with the one-dimensional Wong formula fail to address the fusion data of 8^16O＋50^112,116,120Sn reactions.Such discrepancies can be removed if one uses couplings to internal structure degrees of freedom of colliding nuclei.However, the energy-dependent Woods–Saxon potential model（EDWSP model） accurately describes the sub-barrier fusion enhancement of 8^16O＋50^112,116,120Sn reactions. Therefore, in sub-barrier fusion dynamics, energy dependence in the nucleus–nucleus potential governs barrier modification effects in a closely similar way to that of the coupled channel approach.