Thèse de doctorat
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 Z) target.

In order to correctly extract information about the structure of

these nuclei from experimental cross sections, an accurate

theoretical description of this mechanism is necessary.

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: 11Be, 15C and 8B.

11Be is the best known one-neutron halo nucleus.

Its Coulomb breakup has been extensively studied both experimentally

and theoretically.

Nevertheless, some uncertainty remains about its structure.

The good agreement between our calculations and recent

experimental data suggests that it can be seen as a

s1/2 neutron loosely bound to a 10Be core in its

0+ ground state.

However, the extraction of the corresponding spectroscopic factor

have to wait for the publication of these data.

15C is a candidate one-neutron halo nucleus

whose Coulomb breakup has just been studied experimentally.

The results of our model are in good agreement with

the preliminary experimental data. It seems therefore that

15C can be seen as a 14C core in its 0+

ground state surrounded by a s1/2 neutron.

Our analysis suggests that the spectroscopic factor

corresponding to this configuration should be slightly lower

than unity.

We have also used our method to study the Coulomb breakup

of the candidate one-proton halo nucleus 8B.

Unfortunately, no quantitative agreement could be obtained

between our results and the experimental data.

This is mainly due to an inaccuracy in the treatment

of the results of our calculations.

Accordingly, no conclusion can be drawn about the pertinence

of the two-body model of 8B before an accurate reanalysis of these


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.