A Systematic Analysis of the Charge Radii of Medium Mass Nuclei in the Shell Model Framework

Due to the short range interaction of the nucleon-nucleon force, the nuclear surface is well delimited and therefore the nuclear radius. This fundamental nuclear property is so far, however, not satisfactorily described by microscopic nuclear methods. Theoretical models based on different approaches disagree in the predictions and with the available experimental data. In this thesis a systematic study of charge radii and isotopic shifts in nuclei with mass A=16-70 is performed in the framework of the shell model. Nowadays, with the advent of the radioactive beam facilities, it is possible to follow the behaviour of the charge radii as a function of the isospin along isotopic chains towards the drip lines. In the last years it has been put in evidence the fact that nuclear theoretical descriptions are unable to reproduce in detail the experimental findings. On the other hand, shell model analysis of the radii of mirror nuclei has shown very interesting and unexpected behaviour of the radii of single-particle orbits with low angular momentum value. In addition, it has been shown that due to the isovector monopole polarization, neutron and proton radii keep almost equal, independently of the neutron excess. Based on these evidences, a systematic analysis of isotopic shifts of nuclei with protons filling the sd and pf shells is performed in the framework of the shell model, using the available theoretical descriptions, in order to better understand the evolution of charge radii with respect to the isospin.