Recent MCSM studies on shells, shapes and clustering in atomic nuclei

by Otsuka Takaharu (University of Tokyo)

Wednesday 19 Oct 2022, 11:00 → 12:00 Europe/Rome

1/2-07 - Sala 207 (Dipartimento di Fisica e Astronomia - Edificio Paolotti)

An overview of recent outcomes from studies on the shell structure, the shape deformation and the alpha clustering of atomic nuclei will be presented. These studies utilized relevant results of the Monte Carlo Shell Model (MCSM).  The shell structure of exotic nuclei shows the shell evolution as functions of Z and N, and specific parts of the nuclear forces have direct impacts on this phenomenon.  These parts are the central and tensor terms and it will be shown how they work. The resultant shell evolution is seen in nuclei lighter than A~80, but seems to be invisible for heavier nuclei.  This is obviously due to the dominance of shape deformation in heavy nuclei. Such heavy nuclei are under the same central plus tensor forces, and one of the consequences is the shift to triaxial shapes from the traditional picture of the dominant axial symmetry.  In particular, this change will be discussed for nuclei around 166Er using most advanced MCSM results, mentioning that the picture of A. Bohr may not be applied to a rather majority of nuclei. The third subject concerns the ab initio no-core MCSM calculations for Be and C isotopes, particularly for the ground and Hoyle states of 12C.  Novel pictures and results will be presented, including a crossover between the normal nuclear-matter and clustering pictures.