Dynamic polarization potentials for 6He + 209Bi and 11Li + 208Pb systems at near-barrier energies

2015

Phys. Scr.

This paper addresses the validity of the static Woods-Saxon potential and the energy dependent Woods-Saxon potential (EDWSP) for description of sub-barrier fusion dynamics. The low lying surface vibrations of colliding nuclei and neutron transfer channels are found to be major factors responsible for fusion enhancement at sub-barrier energies. Theoretical calculations based upon the static Woods-Saxon potential obtained using the one-dimensional Wong formula fail to explain the energy dependence of the sub-barrier fusion cross-section of + Ca Ti 40 20 46,48,50 22 Keywords: depth and diffuseness of Woods-Saxon potential, coupled channel equations, heavyion sub-barrier fusion reactions, diffuseness anomaly

Section: Introductionmentioning

confidence: 99%

Systematic failure of static nucleus–nucleus potential to explore sub-barrier fusion dynamics

2015

Phys. Scr.

“…In this connection, many attempts have been made to deduce the relevant information regarding the optimum form of nuclear potential by analyzing the large set of experimental data [10][11][12][13][14][15][16][17]. Generally, the static Woods-Saxon potential is most frequently used to address the heavy-ion reactions.…”

Section: Introductionmentioning

confidence: 99%

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

2015

Indian J Phys

We have analyzed the role of barrier modification effects (barrier height, barrier position, barrier curvature) introduced due to the energy-dependent Woods-Saxon potential model (EDWSP model) and the coupled channel model on the sub-barrier fusion dynamics of 32;36 16 S þ 90;96 40 Zr reactions. The influence of inelastic surface excitations of colliding pairs and multi-neutron transfer channels is found to be a dominant mode of couplings. The coupling of relative motion of colliding nuclei to these dominant intrinsic degrees of freedom leads to a substantially large fusion enhancement at belowbarrier energies over the expectations of one-dimensional barrier penetration model. The coupled channel calculations based upon static Woods-Saxon potential must include the internal nuclear structure degrees of freedom of colliding nuclei for complete description of experimental data. On the other hand, theoretical calculations based upon the EDWSP model along with Wong formula provide a complete description of sub-barrier fusion enhancement of various heavy-ion fusion reactions. In EDWSP model calculations, significantly larger values of diffuseness parameter ranging from a = 0.98 fm to a = 0.85 fm are required to address the observed sub-barrier fusion enhancement of 32;36 16 S þ 90;96 40 Zr reactions. Furthermore, within the context of EDWSP model, it is possible to achieve an agreement with the experimental fusion crosssectional data within 10 %. For four heavy-ion fusion reactions, only at 4 fusion data points out of 90 fusion data points deviates exceeding 5 %, while 86 fusion data points lie within 5 % and hence the EDWSP model is able to account the above-barrier portion of the fusion cross-sectional data within 5 % with a probability greater than 90 %.

“…Because of the existence of large ambiguities in the optimum choice of nucleus-nucleus potential, various aspects of sub-barrier fusion dynamics are still unexplored. To explain the different nuclear interactions, large numbers of parameterizations of nuclear potential are available in the literature, and are regularly used in connection with nuclear reaction studies [18][19][20][21][22][23][24]. Generally, the static Woods-Saxon potential, which is controlled by three parameters-depth, range and diffuseness-is used to describe the dynamics of the fusion process.…”

Section: Introductionmentioning

confidence: 99%

Static versus energy-dependent nucleus-nucleus potential for description of sub-barrier fusion dynamics of ${}_{8}^{16}{\rm O}+{}^{112,116,120}\!\!\!\!\!\!{}_{50}{\rm Sn}$ reactions

2015

Chinese Phys. C

The static and energy-dependent nucleus-nucleus potentials are simultaneously used along with the Wong formula for exploration of fusion dynamics of 16 8 O+ 112,116,120 50 Sn 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 16 8 O+ 112,116,120 50 Sn 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 16 8 O+ 112,116,120 50 Sn 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.