Fusion of28Si +28Si: oscillations above the barrier and the behavior down to 1μb

Stefanini, A. M.; Montagnoli, G.; Corradi, L.; Courtin, S.; Fioretto, E.; Grȩbosz, J.; Haas, F.; Jia, H. M.; Mazzocco, M.; Michelagnoli, C.; Mijatović, T.; Montanari, D.; Parascandolo, C.; Scarlassara, F.; Strano, E.; Szilner, S.; Torresi, D.; Ur, C. A.

doi:10.1051/epjconf/20146603082

Cited by 4 publications

(4 citation statements)

References 8 publications

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“…Very recently Stefanini et al [34] have made more detailed measurements for this system with a very small energy step (around 0.25 MeV in the center-of-mass system) and with better statistics (better than 1%). Their experimental data, when displayed as d{Ecr)/dE, indicate distinct structures at energies only around 5 MeV above the barrier.…”

Section: Heavier Systemsmentioning

confidence: 99%

“…This observation is incompatible with the mechanism discussed here, and the oscillations in the new experimental data must have a different origin. Their presence appears to be related to strong couplings to the low-lying collective modes that exist in the 28 Si nucleus but also seems to depend on the nature of the absorptive potential used in the calculations [4,34], In order to look for the effects of channel couplings, the "experimental barrier distribution" [17,18], D(E) = d? (Ea)/dE2, is frequently used, and in the present context one should remember that the function d{Ecr)/dE can also have structures close to the unperturbed Coulomb barrier due to couplings.…”

Section: Heavier Systemsmentioning

confidence: 99%

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Examination of fusion cross sections and fusion oscillations with a generalized Wong formula

Rowley

Hagino

2015

Phys. Rev. C

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International audienceWe re-examine the well-known Wong formula for heavy-ion fusion cross sections. Although this celebrated formula yields almost-exact results for single-channel calculations for relatively heavy systems such as O16+Sm144, it tends to overestimate the cross section for light systems such as C12+C12. We generalize the formula to take account of the energy dependence of the barrier parameters and show that the energy-dependent version gives results practically indistinguishable from a full quantal calculation. We then examine the deviations arising from the discrete nature of the intervening angular momenta, whose effect can lead to an oscillatory contribution to the excitation function. We recall some compact, analytic expressions for these oscillations and highlight the important physical parameters that give rise to them. Oscillations in symmetric systems are discussed, as are systems where the target and projectile identities can be exchanged via a strong transfer channel

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Section: Heavier Systemsmentioning

confidence: 99%

Section: Heavier Systemsmentioning

confidence: 99%

Examination of fusion cross sections and fusion oscillations with a generalized Wong formula

Rowley

Hagino

2015

Phys. Rev. C

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“…Better data are clearly required to resolve this question, and to establish the existence or absence of any oscillations due to symmetrization. Very recently Stefanini et al [33] have made more detailed measurements for this system with a very small energy step (around 0.25 MeV in the center-of-mass system) and with better statistics (better than 1%). Their experimental data, when displayed as d(Eσ)/dE, indicate distinct structures at energies only around 5 MeV above the barrier.…”

Section: Heavier Systemsmentioning

confidence: 99%

Section: Heavier Systemsmentioning

confidence: 99%

On the Wong cross section and fusion oscillations

Rowley,

Hagino

2015

Preprint

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We re-examine the well-known Wong formula for heavy-ion fusion cross sections. Although this celebrated formula yields almost exact results for single-channel calculations for relatively heavy systems such as 16 O+ 144 Sm, it tends to overestimate the cross section for light systems such as 12 C+ 12 C. We generalise the formula to take account of the energy dependence of the barrier parameters and show that the energy-dependent version gives results practically indistinguishable from a full quantal calculation. We then examine the deviations arising from the discrete nature of the intervening angular momenta, whose effect can lead to an oscillatory contribution to the excitation function. We recall some compact, analytic expressions for these oscillations, and highlight the important physical parameters that give rise to them. Oscillations in symmetric systems are discussed, as are systems where the target and projectile identities can be exchanged via a strong transfer channel.

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Oscillations above the barrier in the fusion of 28Si + 28Si

et al. 2015

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Fusion cross sections of 28 Si + 28 Si have been measured in a range above the barrier with a very small energy step ( E lab = 0.5 MeV). Regular oscillations have been observed, best evidenced in the first derivative of the energy-weighted excitation function. For the first time, quite different behaviors (the appearance of oscillations and the trend of sub-barrier cross sections) have been reproduced within the same theoretical frame, i.e., the coupled-channel model using the shallow M3Y + repulsion potential. The calculations suggest that channel couplings play an important role in the appearance of the oscillations, and that the simple relation between a peak in the derivative of the energy-weighted cross section and the height of a centrifugal barrier is lost, and so is the interpretation of the second derivative of the excitation function as a barrier distribution for this system, at energies above the Coulomb barrier.

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Fusion of²⁸Si +²⁸Si: oscillations above the barrier and the behavior down to 1μb

Cited by 4 publications

References 8 publications

Examination of fusion cross sections and fusion oscillations with a generalized Wong formula

Examination of fusion cross sections and fusion oscillations with a generalized Wong formula

On the Wong cross section and fusion oscillations

Oscillations above the barrier in the fusion of 28Si + 28Si

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