Auteur |
Capel, Pierre (pierre.capel@centraliens.net) |

Titre |
Coulomb breakup of halo nuclei by a time-dependent method |

Département |
F515 - Faculté des sciences appliquées - Physique |

Intitulé du diplôme |
Doctorat en sciences appliquées |

Date de défense |
2004-01-29 |

Jury |
Godefroid, Michel (Membre du jury/Committee Member) Leclercq-Willain, Christiane (Membre du jury/Committee Member) Michel, Francis (Membre du jury/Committee Member) Thompson, Ian (Membre du jury/Committee Member) Beauwens, Robert (Président du jury/Committee Chair) Baye, Daniel (Promoteur/Director) |

Mots-clés |
dissociation reaction, three-dimensional mesh method, time-dependent Schrödinger equation, semiclassical approximation, exotic nuclei |

Résumé |
Halo nuclei are among the strangest nuclear structures.
They are viewed as a core containing most of the nucleons
surrounded by one or two loosely bound nucleons.
These have a high probability of presence at a large distance
from the core.
Therefore, they constitute a sort of halo surrounding the other nucleons.
The core, remaining almost unperturbed by the presence
of the halo is seen as a usual nucleus.
The Coulomb breakup reaction is one of the most useful
tools to study these nuclei. It corresponds to the
dissociation of the halo from the core during a collision
with a heavy (high In this work, we present a theoretical method for studying the Coulomb breakup of one-nucleon halo nuclei. This method is based on a semiclassical approximation in which the projectile is assumed to follow a classical trajectory. In this approximation, the projectile is seen as evolving in a time-varying potential simulating its interaction with the target. This leads to the resolution of a time-dependent Schrödinger equation for the projectile wave function. In our method, the halo nucleus is described with a two-body structure: a pointlike nucleon linked to a pointlike core. In the present state of our model, the interaction between the two clusters is modelled by a local potential. The main idea of our method is to expand the projectile wave function on a three-dimensional spherical mesh. With this mesh, the representation of the time-dependent potential is fully diagonal. Furthermore, it leads to a simple representation of the Hamiltonian modelling the halo nucleus. This expansion is used to derive an accurate evolution algorithm.
With this method, we study the Coulomb breakup
of three nuclei:
We have also used our method to study the Coulomb breakup
of the candidate one-proton halo nucleus In the future, we plan to improve our method in two ways. The first concerns the modelling of the halo nuclei. It would be indeed of particular interest to test other models of halo nuclei than the simple two-body structure used up to now. The second is the extension of this semiclassical model to two-neutron halo nuclei. However, this cannot be achieved without improving significantly the time-evolution algorithm so as to reach affordable computational times. |