Comprehensive analysis of heavy-ion fusion reactions around the Coulomb barrier
Vijay, Manjeet Singh Gautam, Rishi Pal Chahal, Sukhvinder Duhan, Hitender Khatri
Abstract
Abstract We have investigated the fusion dynamics of 12 C + 92 Zr, 16 O + 92 Zr, 28 Si + 92 Zr, 35 Cl + 92 Zr, 16 O + 60 Ni, 18 O + 58 Ni, 12 C + 194,198 Pt, 16 O + 144,148,154 Sm and 17 O + 144 Sm reactions in the close vicinity of the Coulomb barrier. For this purpose, we have opted one-dimensional Wong formula, coupled channel approach, and symmetric-asymmetric Gaussian barrier distribution (SAGBD) model to analyze the fusion data for above mentioned reactions. For all studied systems, the theoretical results obtained from the one-dimensional Wong formula are unable to reproduce the fusion data especially at incident energies lying below the nominal barrier. This appeals for the inclusion of intrinsic degrees of freedom which have been originated from the nuclear structure of fusing nuclei, and thus essentially required to explain the experimental data at energies lying in the sub-barrier realm. For the chosen reactions, the coupled channel analysis suggests that the coupling of relative motion with the inelastic surface excitations and/or nucleon transfer channels associated with the reaction partners have produced a remarkable fusion enhancement at energies lying near and below the nominal barrier. It is particularly intriguing that the SAGBD model can replicate the impacts of dominant intrinsic reaction channels such as multi-phonon quantum states and/or nucleon transfer channels via Gaussian type of weight function. The predictions of the SAGBD approach appropriately reproduce the fusion cross-sections data and related barrier distributions data for the selected reactions due the fact that the multi-dimensional nature induces the barrier lowering effects and subsequently reduces the effective fusion barrier between the participants. In the SAGBD approach, the channel coupling effects are quantitively measured in terms of channel coupling parameter <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:mi>λ</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:math> and percentage decrement in height of effective fusion barrier with respect to the Coulomb barrier <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>V</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>C</mml:mi> <mml:mi>B</mml:mi> <mml:mi>R</mml:mi> <mml:mi>E</mml:mi> <mml:mi>D</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> <mml:mo>.</mml:mo> </mml:math> Furthermore, the recovered <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mi>χ</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msup> </mml:math> -values for selected reactions are found to be smaller and hence clearly demonstrate the applicability of the model outcomes to explore the fusion dynamics of the studied systems.