Clustering in neutron-rich nuclei

Clustering in nuclei is discussed putting emphasis on the investigation of the role of nuclear clustering in neutron-rich nuclei. The subjects we discuss include clustering in neutron-rich Be, B and C isotopes, clustering in the island of inversion around N = 20, and clustering in the region with A approximate to 40. Be isotopes present us typical examples of clustering in neutron-rich nuclei not only in their ground band states but also in their excited band states, for which we show the analyses based on antisymmetrized molecular dynamics (AMD). Clustering in Be isotopes near neutron dripline is intimately related to the breaking of the neutron magic number N = 8. In this connection we report our study about the possible relation of the clustering with the breaking of the neutron magic number N = 20 in the island of inversion including Mg-32 and Ne-30. Our discussion is not only about the positive parity states but also about negative parity states. Recently in the latter half of sd shell and in the pf shell many excited rotational bands with large deformation have been found to exist. Since the first excited K-pi = 0(+) and K-pi = 0(-) bands in Ca-40 have been regarded as constituting inversion doublet bands having the Ar-36 + alpha structure, and since the first excited K-pi = 0(+) band in K-pi = 0(-) has been concluded to have Ca-40 + alpha structure through the a transfer reaction and by using the unique alpha optical potential on Ca-40, it is important to investigate the role of a clustering in these newly-found rotational bands with large deformation. We will report the AMD study about this problem.