Near- and sub-barrier fusion of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Ni</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>58</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>with<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Ni</mml:mi></mml:mrow><mml:mpresc

Beckerman, M.; Ball, John A.; Enge, H.A.; Salomaa, M.; Sperduto, A.; Gazes, S.B.; DiRienzo, A.; Molitoris, J. D.

doi:10.1103/physrevc.23.1581

Cited by 135 publications

(73 citation statements)

References 31 publications

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“…The Sommerfeld parameter is given by η = e 2 Z t Z p / ν, where Z t and Z p are the charges of the target and projectile, respectively, and ν is the relative velocity between the target and projectile in the center-of-mass frame. The logarithmic derivative of the fusion cross section is given by L(E) = [5,[34][35][36], respectively. In the figure, one can see that drastic improvements have been made by taking into account the damping in the CC form factor, as compared to the results calculated without the damping factor.…”

Section: Calculation Resultsmentioning

confidence: 99%

Systematic investigations of deep sub-barrier fusion reactions using an adiabatic approach

Ichikawa

2015

Phys. Rev. C

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Background: At extremely low incident energies, unexpected decreases in fusion cross sections, compared to the standard coupled-channels (CC) calculations, have been observed in a wide range of fusion reactions. These significant reductions of the fusion cross sections are often referred to as the fusion hindrance. However, the physical origin of the fusion hindrance is still unclear.Purpose: To describe the fusion hindrance based on an adiabatic approach, I propose a novel extension of the standard CC model by introducing a damping factor that describes a smooth transition from sudden to adiabatic processes. I demonstrate the performance of this model by systematically investigating various deep sub-barrier fusion reactions.Method: I extend the standard CC model by introducing a damping factor into the coupling matrix elements in the standard CC model. This avoids double counting of the CC effects, when two colliding nuclei overlap one another. I adopt the Yukawa-plusexponential (YPE) model as a basic heavy ion-ion potential, which is advantageous for a unified description of the one-and two-body potentials. For the purpose of these systematic investigations, I approximate the one-body potential with a third-order polynomial function based on the YPE model. O + 208 Pb are consistent with the experimental data. The astrophysical S factor and logarithmic derivative representations of these are also in good agreement with the experimental data. The values obtained for the individual radius and diffuseness parameters in the damping factor, which reproduce the fusion cross sections well, are nearly equal to the average value for all the systems. Results Conclusions:Since the results calculated with the damping factor are in excellent agreement with the experimental data in all systems, I conclude that the smooth transition from the sudden to adiabatic processes occurs and that a coordinate-dependent coupling strength is responsible for the fusion hindrance. In all systems, the potential energies at the touching point V Touch strongly correlate with the incident threshold energies for which the fusion hindrance starts to emerge, except for the mediumlight mass systems.

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Section: Calculation Resultsmentioning

confidence: 99%

Systematic investigations of deep sub-barrier fusion reactions using an adiabatic approach

Ichikawa

2015

Phys. Rev. C

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“…3, we show the dependence of the fusion cross section (upper panel) and of the logarithmic slope (lower panel) on the surface diffuseness parameter a for the 58 Ni + 58 Ni reaction. The figure also includes the experimental data [21] for comparison. The experimental slope was computed using point-difference formulae with both two and three successive data points.…”

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confidence: 99%

Fusion cross sections at deep sub-barrier energies

2003

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A recent publication reports that heavy-ion fusion cross sections at extreme subbarrier energies show a continuous change of their logarithmic slope with decreasing energy, resulting in a much steeper excitation function compared with theoretical predictions. We show that the energy dependence of this slope is partly due to the asymmetric shape of the Coulomb barrier, that is its deviation from a harmonic shape. We also point out that the large low-energy slope is consistent with the surprisingly large surface diffusenesses required to fit recent high-precision fusion data.

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“…In the context of this paper, we would first like to review briefly the results obtained for the the Ca+Ca and Ni+Ni systems where fusion cross sections have been measured from well above the barrier down to very low cross section [1,2,4,5]. All systems studied, except 40 Ca + 48 Ca have negative Q values for fusion.…”

Section: Previous Results Concerning the Ca+ca And Ni+ni Systemsmentioning

confidence: 99%

Exploring the influence of transfer channels on fusion reactions: the case of⁴⁰Ca +^58,64Ni

Bourgin

Courtin

Haas

et al. 2015

EPJ Web of Conferences

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Abstract. Fusion cross sections have been measured in the 40 Ca + 58 Ni and 40 Ca + 64 Ni systems at beam energies ranging from E lab = 104.75 MeV to 153.5 MeV using the Laboratori Nazionali di Legnaro electrostatic deflector. Distributions of barriers have been extracted from the experimental data. Preliminary coupled channel calculations were performed and hints of effects of neutron transfers on the fusion below the barrier in the 40 Ca + 64 Ni are discussed.

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Near- and sub-barrier fusion ofNi58withNi

Cited by 135 publications

References 31 publications

Systematic investigations of deep sub-barrier fusion reactions using an adiabatic approach

Systematic investigations of deep sub-barrier fusion reactions using an adiabatic approach

Fusion cross sections at deep sub-barrier energies

Exploring the influence of transfer channels on fusion reactions: the case of⁴⁰Ca +^58,64Ni

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Near- and sub-barrier fusion ofNi58withNi

Cited by 135 publications

References 31 publications

Systematic investigations of deep sub-barrier fusion reactions using an adiabatic approach

Systematic investigations of deep sub-barrier fusion reactions using an adiabatic approach

Fusion cross sections at deep sub-barrier energies

Exploring the influence of transfer channels on fusion reactions: the case of40Ca +58,64Ni

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Exploring the influence of transfer channels on fusion reactions: the case of⁴⁰Ca +^58,64Ni