Effects of finite width of excited states on heavy-ion sub-barrier fusion reactions

Hagino, K.; Takigawa, N.

doi:10.1103/physrevc.58.2872

Cited by 11 publications

(11 citation statements)

References 36 publications

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“…Neither existing models of fusion nor of deep-inelastic scattering can address both energy dissipation and quantum tunneling. The impact of finite lifetimes of excited states (e.g., giant resonances) on fusion has been studied within a coupled-channels model [10,11,12], but this approach does not lead to energy dissipation. Direct damped collisions between complex nuclei have also been intensively investigated within various approaches, including: (i) transport theories [13] based on premaster, master, Fokker-Planck, Langevin and diffusion equations, and (ii) quantum mechanical collective theories [14].…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Dissipative quantum dynamics in low-energy collisions of complex nuclei

et al. 2008

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Model calculations that include the effects of irreversible, environmental couplings on top of a coupled-channels dynamical description of the collision of two complex nuclei are presented. The Liouville-von Neumann equation for the time evolution of the density matrix of a dissipative system is solved numerically providing a consistent transition from coherent to decoherent (and dissipative) dynamics during the collision. Quantum decoherence and dissipation are clearly manifested in the model calculations. Energy dissipation, due to the irreversible decay of giant-dipole vibrational states of the colliding nuclei, is shown to result in a hindrance of quantum tunneling and fusion.

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Section: Theoretical Backgroundmentioning

confidence: 99%

Dissipative quantum dynamics in low-energy collisions of complex nuclei

et al. 2008

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“…For = 2 and R = 1.2A 1/3 fm, ␤ 2 = 3.04A −2/3 , giving a variation in ␤ 2 from the rather small value of 0.087 for 208 Pb to 0.58 for 12 C. The realistic all-order coupled channels code CCFULL [8] has been used to estimate the barrier shifts due to the GQR, ␤ 2 values for both target and projectile being included. The finite width [42] of the GQR was not taken into account as the effects are not expected to be significant. Also shown in Fig.…”

Section: Effect Of Giant Resonancesmentioning

confidence: 99%

Systematic failure of the Woods-Saxon nuclear potential to describe both fusion and elastic scattering: Possible need for a new dynamical approach to fusion

et al. 2004

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A large number of precision fusion excitation functions, at energies above the average fusion barriers, have been fitted using the Woods-Saxon form for the nuclear potential in a barrier passing model of fusion. They give values for the empirical diffuseness parameter a ranging between 0.75 and 1.5 fm, compared with values of about 0.65 fm which generally reproduce elastic scattering data. There is a clear tendency for the deduced a to increase strongly with the reaction charge product Z 1 Z 2 , and some evidence for the effect of nuclear structure on the value of a, particularly with regard to the degree of neutron richness of the fusing nuclei, and possibly with regard to deformation. The measured fusion-barrier energies are always lower than those of the bare potentials used, which is expected as a result of adiabatic coupling to high energy collective states. This difference increases with increasing Z 1 Z 2 and calculations show that about 1 / 3 of it may be attributed to coupling to the isoscalar giant-quadrupole resonances in the target and projectile. Coupling to all giant resonances may account for a significant part. Fluctuations about the trend line may be due to systematic errors in the data and/or structure effects such as coupling to collective octupole states. Previously suggested reasons for the large values of a have been related to departures from the Woods-Saxon potential and to dissipative effects. This work suggests that the apparently large values of a may be an artifact of trying to describe the dynamical fusion process by use of a static potential. Another partial explaination might reside in fusion inhibition, due for example to deep-inelastic scattering, again a process requiring dynamical calculations.

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“…In fact, the effect of the widths of these resonances (excited states with finite life times) was studied in Refs. [26,27]. The overall effect of the width as compared to bound excited state, is a reduction in fusion.…”

Section: Theoretical Modelsmentioning

confidence: 99%

Fusion and breakup of halo nuclei

Hussein¹,

Canto²,

Donangelo³

2003

Nuclear Physics A

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We discuss the effect of the coupling to the break-up channel on the total fusion involving a halo nucleus with a heavy target. We show that there is a competition between the hindrance arising from this coupling mostly at above barrier energies, and the enhancement which ensues at sub-barrier energies owing to the static effect of the extended matter distribution and the coupling to the soft modes.

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Effects of finite width of excited states on heavy-ion sub-barrier fusion reactions

Cited by 11 publications

References 36 publications

Dissipative quantum dynamics in low-energy collisions of complex nuclei

Dissipative quantum dynamics in low-energy collisions of complex nuclei

Systematic failure of the Woods-Saxon nuclear potential to describe both fusion and elastic scattering: Possible need for a new dynamical approach to fusion

Fusion and breakup of halo nuclei

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