Conveners
Clustering and shape-phase transitions in nuclei and other physical systems
- Roelof Bijker
- Francisco Perez-Bernal
Clustering and shape-phase transitions in nuclei and other physical systems
- Francisco Perez-Bernal
- Roelof Bijker
Nucleon localization, and formation of clusters in nucleonic matter and finite nuclei are explored in a framework based on nuclear energy density functionals. The liquid-cluster transition is investigated and different measures of localization are discussed. The formation and evolution of alpha-clusters in excited states of light and heavy nuclei are analysed.
In this contribution I present some recent
results on alpha-particle clustering in odd-mass nuclei,
in particular, on electromagnetic transitions and
longitudinal and transverse form factors.
Results obtained in the last few years by the Theoretical Nuclear Physics group in Padova on alpha-cluster models and on nuclear correlations in halo nuclei will be reviewed in this seminar. The algebraic cluster model assumes triangular and tetrahedral configurations of alpha particles for carbon-12 and oxygen-16 respectively. The spectroscopic description of the low-lying states achieved in...
The magnetic dipole moments in even-even self-conjugate nuclei from $^{12}$C to $^{44}$Ti are investigated. For the latter, the measured gyromagnetic factors of excited states turn out to assume the same value of $g\approx+0.5$ within statistical errors. This peculiar feature can be interpreted on the basis of collective excitations of $\alpha$-clusters. Analogously, the behaviour of the same...
Molecular bending spectra can be broadly categorized into three physical cases, depending on the molecular equilibrium configuration: linear, bent, and nonrigid. We have studied the three cases in detail with an extended Hamiltonian (including up to four-body interactions) of the 2D limit of the Vibron Model (2DVM), and analyzed shape transitions such as bent to linear transition [1], and...
Axial nuclear deformation results in a splitting of the isovector Giant Dipole Resonance into two parts, corresponding to oscillations along and perpendicular to the symmetry axis of the nucleus ($K$-splitting). A similar sensitivity is expected for the Pygmy Dipole Resonance (PDR) [1], a low-lying enhancement of E1 strength observed for heavy nuclei that is often attributed to a...
The giant dipole resonance (GDR) is one of the most fundamental nuclear excitations and dominates the dipole response of all nuclei. Its evolution from a single-humped structure to a double-humped structure is considered as one of the most direct signatures of collectivity and nuclear deformation. Yet, its $\gamma$-decay behavior, despite being a key property, is still mostly...
Using covariant density functional theory with the DDME2 functional and labeling single particle energy orbitals by Nilsson quantum numbers [1], a search for particle-hole (p-h) excitations connected to the appearance of shape coexistence is performed for Z=38 to 84 nuclei [2]. Islands of shape coexistence are found near the magic numbers Z=82 and Z=50, restricted in regions around the...
