Diffuseness of Woods–axon Potential and Sub-Barrier Fusion

Abstract

We have proposed an energy-dependent parametrization scheme for determining the diffuseness parameter of Woods–Saxon potential which when used in conjunction with the coupled channel code CCFULL explains very well the fusion excitation function data around the barrier for various systems.

Relative importance of energy dependent diffuseness parameter and barrier position in the analysis of fusion excitation function data

“…As the value of diffuseness parameter increases beyond 0.65 a fm  , the potential pocket becomes more and more shallow and disappears for large values and the fusion barrier radius decreases rapidly [6,[13][14][15]. Very recently, an energy dependent parameterization scheme to determine the value of diffuseness parameter was successfully used to explain the fusion excitation functions of various systems [16]. Since, the barrier position changes with the change in the shape of the potential, the energy dependent potential induces energy dependence in the barrier position also.…”

Effects of intrinsic degrees of freedom in enhancement of sub-barrier fusion excitation function data and energy-dependent one-dimensional barrier penetration model

“…The role of internal structure degrees of freedom of colliding nuclei is entertained within the framework of coupled channel calculations performed by using the code CCFULL [34]. In EDWSP model, the energy dependence of Woods-Saxon potential induces similar kinds of static and dynamical physical effects as deduced from the channel coupling effects and hence brings the larger fusion enhancement at below-barrier energies with respect to the energy-independent one-dimensional barrier penetration model as evident from the earlier works [21][22][23][24][25][26][27][28][29][30][31][32][33].…”

“…In the previous work, the energy-dependent Woods-Saxon potential model (EDWSP model) has been successfully used to address the role of inelastic surface vibrations of colliding pairs and the multi-neutron transfer channels [21][22][23][24][25][26][27][28][29][30][31][32][33]. The form of static Woods-Saxon potential is defined as…”

“…The present parameterization of potential depth is based upon the reproduction the fusion excitation function data of wide range of projectile-target combinations ranging from Z P Z T = 84 to Z P Z T = 1640 [21][22][23][24][25][26][27][28][29][30][31][32][33]. In fusion process, the various kinds of static and dynamical physical effects such as variations of densities of colliding nuclei, dissipation of kinetic energy of relative motion into internal structure degrees of freedom, different kinds of channel couplings effects (influences of inelastic surface vibrational states, rotational states of deformed nuclei, multi-nucleon transfer channels) or other static and dynamical physical effects occur in the surface region of nuclear potential or in the tail region of Coulomb barrier.…”

“…This diffuseness anomaly, which reflects the inconsistency of static Woods-Saxon potential for simultaneously exploring of elastic scattering and fusion process, may be associated with various kinds of static and dynamical physical effects [1][2][3][4][5][6][7][18][19][20]. To understand the cause of diffuseness anomaly and the puzzling behavior of sub-barrier fusion data, in the present work we have analyzed the fusion dynamics of 32;36 16 S þ 90;96 40 Zr systems within the context of the coupled channel approach and the energy-dependent Woods-Saxon potential model (EDWSP model) [21][22][23][24][25][26][27][28][29][30][31][32][33]. The role of internal structure degrees of freedom of colliding nuclei is entertained within the framework of coupled channel calculations performed by using the code CCFULL [34].…”