exotic nuclei structure and reaction noyaux exotiques ... - IPN - IN2P3
exotic nuclei structure and reaction noyaux exotiques ... - IPN - IN2P3
exotic nuclei structure and reaction noyaux exotiques ... - IPN - IN2P3
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Collective excitations with SKYRME second RPA<br />
<strong>IPN</strong>O Participation: M. Grasso<br />
Collaboration : University of Catania <strong>and</strong> INFN, Sezione di Catania<br />
Des applications de la Seconde RPA avec l’interaction de Skyrme sont effectuées pour décrire les modes<br />
d’excitations du noyau 16 O. Le couplage entre les configurations 1 particule-1 trou et 2 particule-2 trou et<br />
celui entre les configurations 2 particule-2 trou sont pris en compte de manière complète.<br />
Une caractéristique des résultats de la Seconde RPA est que le spectre est déplacé de plusieurs MeV vers<br />
des énergies plus basse par rapport au spectre correspondant obtenu avec la RPA ordinaire.<br />
Une fragmentation plus importante de la réponse est aussi obtenue avec la Seconde RPA grâce au nombre<br />
très élevé de configurations 2 particule– 2 trou. Une meilleure description des états de basse énergie 0 +<br />
et 2 + est réalisée avec la Seconde RPA.<br />
In Ref. [1] Second RPA calculations with a Skyrme<br />
force are performed to describe nuclear collective<br />
<strong>and</strong> low-lying excited states in 16 O.<br />
The coupling between 1 particle-1 hole <strong>and</strong> 2 particle-2<br />
hole as well as that between 2 particle-2 hole<br />
configurations among themselves are fully taken<br />
into account <strong>and</strong> the residual interaction is never<br />
neglected,not resorting therefore to a generally<br />
used approximate scheme where only the first kind<br />
of coupling is considered.<br />
The issue of the rearrangement terms inthe matrix<br />
elements beyond st<strong>and</strong>ard RPA is addressed <strong>and</strong><br />
discussed.<br />
As a general feature of second RPA results, a several-MeV<br />
shift of the strength distribution to lower<br />
energies is systematically found with respect to<br />
A much more important fragmentation of the<br />
strength is also naturally provided by second RPA<br />
due to the huge number of 2 particle-2 hole configurations.<br />
A better description of the excitation energies of<br />
the low-lying 0 + <strong>and</strong> 2 + states is obtained with second<br />
RPA with respect to RPA because 2 particle-<br />
2 hole configurations are also included (see Ref.<br />
[1]).<br />
References:<br />
[1] D. Gambacurta, M. Grasso, <strong>and</strong> F. Catara,<br />
[nucl-th] arXiv1002.3563<br />
A<br />
b<br />
a<br />
x<br />
Fig 1. Quadrupole response<br />
RPA distributions (see for instance Fig. 1 for the<br />
quadrupole strength distributions).<br />
64