Giant Dipole Resonance as a Fingerprint of $α$ Clustering Configurations in $^{12}$C and $^{16}$O

Abstract

It is studied how the $α$ cluster degrees of freedom, such as $α$ clustering configurations close to the $α$ decay threshold in $^{12}$C and $^{16}$O, including the linear chain, triangle, square, kite, and tetrahedron, affect nuclear collective vibrations with a microscopic dynamical approach, which can describe properties of nuclear ground states well across the nuclide chart and reproduce the standard giant dipole resonance (GDR) of $^{16}$O quite nicely. It is found that the GDR spectrum is highly fragmented into several apparent peaks due to the $α$ structure. The different $α$ cluster configurations in $^{12}$C and $^{16}$O have corresponding characteristic spectra of GDR. The number and centroid energies of peaks in the GDR spectra can be reasonably explained by the geometrical and dynamical symmetries of $α$ clustering configurations. Therefore, the GDR can be regarded as a very effective probe to diagnose the different $α$ cluster configurations in light nuclei.

6 pages, 3 figures