Form Factor and New Mean Fields in Bubble Nuclei

Bubble nuclei are an exotic class of nuclear systems showing a central region of reduced nucleon density. The occurrence of such depletion (a bubble)is an interesting nuclear phenomenon, whose underlying microscopic origin provides a rapidly developing field of research in nuclear structure. In the present work, the properties of (medium) bubble nuclei are analyzed using shell model calculations. We addressed the question of deriving a criterion that allows identifying experimentally bubble nuclei using the form factor. As an extension of the seminal work of Wong in the 70 s, different mean fields have been proposed and their properties discussed. In addition, the effect of a bubble structure on the charge density distribution, the form factor and the single-particle levels, is discussed through their dependence on the inner-to-outer radius ratio p. In this way, level crossing and inversion have been obtained. Such results lead to the magic numbers 18 and 32, low angular momentum state occupancy reduction, and hence to candidates for bubble structure in exotic nuclei.