Fusion cross sections of 28Si + 28Si have been measured in a range above the barrier with a very small energy step (ΔElab=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.

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

MONTAGNOLI, GIOVANNA;CORRADI, LAURA;MAZZOCCO, MARCO;MICHELAGNOLI, CATERINA;MONTANARI, DANIELE;PARASCANDOLO, CONCETTA;SCARLASSARA, FERNANDO;STRANO, EMANUELE;TORRESI, DOMENICO MARIO
2015

Abstract

Fusion cross sections of 28Si + 28Si have been measured in a range above the barrier with a very small energy step (ΔElab=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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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3221937
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