In this Thesis we present a description of α cluster nuclei, in particular focusing on the case of 9 Be, with αn and αα interactions derived from Cluster Effective Field Theory (EFT). The two-body potentials are regularized by a Gaussian cutoff which cures the short-distance dependence of the interaction and the potential parameters are found comparing the effective range expansion (ERE) with the calculated T-matrix. The calculation of the ground-state energies is carried out by diagonalizing the Hamiltonian on a Non symmetryzed Hyperspherical Harmonics basis in momentum space. Using
only two body interactions a rather strong cutoff dependence appears. However, we are able to reproduce the experimental ground-state energies for selected cutoff values for most of the studied nuclei. The strong cutoff dependence indicates the lack of three-body forces, therefore we extend our Cluster EFT approach by including such many-body forces. Finally, the 9Be photoabsorption cross-section is studied via the Lorentz integral transform method (LIT), focusing on the low-energy resonances coming from the electric dipole transitions. By fine tuning the parameters of the three-body force, we are able to reproduce, up to 4 MeV, the considered experimental resonances. For the description of the spectrum at higher energies the inclusion of the αα D-wave potential seems to be necessary.
| Identifer | oai:union.ndltd.org:unitn.it/oai:iris.unitn.it:11572/338316 |
| Date | 13 April 2022 |
| Creators | Filandri, Elena |
| Contributors | Filandri, Elena, Leidemann, Winfried |
| Publisher | Università degli studi di Trento, place:TRENTO |
| Source Sets | Università di Trento |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | firstpage:1, lastpage:125, numberofpages:125 |
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