From superdeformation to extreme deformation and clusterization in theN≈Znuclei of theA≈40mass region

Abstract

From superdeformation to extreme deformation and clusterization in the N ∼ Z nuclei of the A ∼ 40 mass region. A systematic search for extremely deformed structures in the N ∼ Z nuclei of the A ∼ 40 mass region has been performed for the first time in the framework of covariant density functional theory. At spin zero such structures are located at high excitation energies which prevents their experimental observation. The rotation acts as a tool to bring these exotic shapes to the yrast line or its vicinity so that their observation could become possible with future generation of γ−tracking (or similar) detectors such as GRETA and AGATA. The major physical observables of such structures (such as transition quadrupole moments as well as kinematic and dynamic moments of inertia), the underlying single-particle structure and the spins at which they become yrast or near yrast are defined. The search for the fingerprints of clusterization and molecular structures is performed and the configurations with such features are discussed. The best candidates for observation of extremely deformed structures are identified. For several nuclei in this study (such as 36 Ar), the addition of several spin units above currently measured maximum spin of 16 will inevitably trigger the transition to hyper-and megadeformed nuclear shapes.

Quadrupole collectivity in Ca42 from low-energy Coulomb excitation with AGATA

“…The sideband based on the 0 + 2 state in 42 Ca seems to correspond to the [4,3]a configuration in Ref. [116], predicted to appear at about 1 MeV excitation energy and to have a transitional quadrupole moment Q t of about 1.5 e b[ a s compared to the experimental value of 1.13(10) e b]. Triaxial deformation of γ ∼−20…”

“…Highly-deformed structures in 42 Ca were also studied in the framework of the cranked relativistic mean-field theory (CRMF) [116]. The model does not assume the existence of cluster structures: their formation proceeds from microscopic single-nucleon degrees of freedom via many-body correlations.…”

“…The structure of 42 Ca was also studied in the framework of the generator coordinate method (GCM) with deformed-basis antisymmetrized molecular dynamics (AMD) wave functions [115], the α + 38 Ar orthogonality condition model (OCM) [87], and covariant relativistic energy density functional theory (CDFT) [116].…”

Recent Experimental Results on Nuclear Cluster Physics

“…The relashionship between α-clustering, nuclear molecules and superdeformation (SD) [8,18,52,53] is of particular interest, since nuclear shapes with major-to-minor axis ratios of 2:1 are typical ellipsoidal elongations for light nuclei (corresponding to a quadrupole deformation parameter β 2 ≈ 0.6). Furthermore, the structure of possible octupole-unstable 3:1 nuclear shapes (hyperdeformation (HD) with β 2 ≈ 1.0) has also been discussed for actinide nuclei in terms of clustering phenomena [8].…”

Solving Dirac equations on a 3D lattice with inverse Hamiltonian and spectral methods

“…In most CDFT applications, the harmonic oscillator basis expansion method has been widely used, which is an very efficient approach and has achieved a great success in not only the description of the single-particle motion in nuclei [19] but also the self-consistent description of nuclear collective modes, such as rotations [20][21][22][23][24][25], vibrations [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41], and isospin excitations, by restoring the symmetries and/or considering quantum fluctuations, see also [7] for details. For exotic nuclei with large spatial distribution, a large basis space is needed to get a quick convergence.…”