Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userEffect of Pauli repulsion and transfer on fusion
97
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The effect of the Pauli exclusion principle on the nucleus-nucleus bare potential is studied using a new density-constrained extension of the Frozen-Hartree-Fock (DCFHF) technique. The resulting potentials exhibit a repulsion at short distance. The charge product dependence of this Pauli repulsion is investigated. Dynamical effects are then included in the potential with the density-constrained time-dependent Hartree-Fock (DCTDHF) method. In particular, isovector contributions to this potential are used to investigate the role of transfer on fusion, resulting in a lowering of the inner part of the potential for systems with positive Q-value transfer channels.
rate research
Read More
Microscopic theories beyond mean-field are developed to include pairing, in-medium nucleon-nucleon collisions as well as effects of initial fluctuations of one-body observables on nuclear dynamics. These theories are applied to nuclear reactions. The role of pairing on nuclear break-up is discussed. By including the effect of zero point motion of collective variables through a stochastic mean-field theory, not only average evolution of one-body observables are properly described but also fluctuations. Diffusion coefficients in fusion as well as mass distributions in transfer reactions are estimated.
Fusion cross-sections are computed for the $^{40}$Ca$+^{40}$Ca system over a wide energy range with two microscopic approaches where the only phenomenological input is the Skyrme energy density functional. The first method is based on the coupled-channels formalism, using the bare nucleus-nucleus potential calculated with the frozen Hartree-Fock technique and the deformation parameters of vibrational states computed with the time-dependent Hartree-Fock (TDHF) approach. The second method is based on the density-constrained TDHF method to generate nucleus-nucleus potentials from TDHF evolution. Both approaches incorporate the effect of couplings to internal degrees of freedoms in different ways. The predictions are in relatively good agreement with experimental data.
Background: Several Time-Dependent Hartree-Fock-Bogoliubov (TDHFB) calculations predict that the super- fluidity enhances the fluctuations of the fusion barrier. This effect is not fully understood and not yet revealed experimentally. Purpose: The goal of this study is to investigate empirically the effect of the superfluidity on the fusion barrier width. Method: First, the local regression method is introduce and used to determine the barrier distribution more precisely. A second method that requires only the calculation of an integral of the cross section is developed to determine accurately the fluctuations of the barrier. A benchmark is done between this two methods and with the fitting method usually used. This integral method showing a better agreement in a test case, it is applied systematically in a selection of 115 fusion reactions. Results: The fluctuations of the barrier for superfluid systems are on average larger than for magic or semi-magic nuclei. This is due to the deformation effects and the effect of the superfluidity. To disentangle those two effects, we compare the experimental width to the width estimated from a model that takes into account the tunneling, the deformation and the vibration effect. The deviation of the experimental width from this theory for reaction between superfluid nuclei shows that the superfluidity enhance the fusion barrier width. Conclusions: This analysis shows that the predicted effect of the superfluidity on the width of the barrier is real and is of the order of 1 MeV.
The time-dependent transition between a diabatic interaction potential in the entrance channel and an adiabatic potential during the fusion process is investigated within the two-center shell model. A large hindrance is obtained for the motion to smaller elongations of near symmetric dinuclear systems. The comparison of the calculated energy thresholds for the complete fusion in different relevant collective variables shows that the dinuclear system prefers to evolve in the mass asymmetry coordinate by nucleon transfer to the compound nucleus.
Results of numerical simulations of fusion rate d(d,p)t, for low-energy deuteron beam, colliding with deuterated metallic matrix (Raiola et al. Phys. Lett.B 547 (2002) 193 and Eur. Phys J. A 13 (2002) 377) confirm analytical estimate given in Coraddu et al. nucl-th/0401043, taking into account quantum tails in the momentum distribution function of target particles, and predict an enhanced astrophysical factor in the 1 keV region in qualitative agreement with experiments.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
