L. El Ouaourti | Searcharxiv

arXiv2026

Probing alternating-parity bands in even-even nuclei within an axial quadrupole-octupole-hexadecapole collective model

An analytic quadrupole octupole hexadecapole (QOH) axially symmetric model is used to provide a coherent framework for describing both octupole vibrations and octupole deformations in even-even nuclei. The model offers analytical solutions for the energy spectra and electric E1, E2 and E3 transition probabilities. The spectroscopic features are governed by three physically meaningful parameters: the stiffness constant $c_2$, the hexadecapole deformation parameter $ϕ_{02}$, and the sextic potential parameter $α$, directly linked to $ϕ_{01}^π$ which represents the interplay between the quadrupole and octupole deformations for both even and odd angular momentum states. The model is applied across a broad range of nuclei including Ra, Th, Sm, Ba, U, Gd, Nd, Rn, Pu, Xe, and Ce isotopes, effectively capturing the characteristic properties of alternating parity bands. Detailed calculations of E1, E2, and E3 transition matrix elements have been performed for $^{220,222}$Rn, $^{222,224,228}$Ra, and $^{144,146}$Ba yielding results in good agreement with available experimental data.

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arXiv2024

Axially Symmetric Quadrupole-Octupole Model incorporating Sextic Potential

We present an extended application of the analytic quadrupole octupole axially symmetric model, originally employed to study the octupole deformation and vibrations in light actinides using an infinite well potential (IW). In this work, we extend the model's applicability to a broader range of nuclei exhibiting octupole deformation by incorporating a sextic potential instead of the Davidson potential.Similarly to conventional models, such as AQOA-IW (for infinite square potential) and AQOA-D (for the Davidson potential), our proposed model is referred to as AQOA-S. By employing the sextic potential, phenomenologically represented as $v(\tildeβ) = a_1\tilde β^2+a_2\tilde β^4+a_3\tilde β^6$, we can derive analytical expressions for the energy spectra and transition rates (B(E1), B(E2), B(E3)). The energy spectra of the model are essentially governed by two critical parameters: $ϕ_0$, indicating the balance between octupole and quadrupole strain, and $α$, a key factor in adjusting the shape and behavior of the spectra through the sextic potential. In terms of applications, the study encompasses five isotopes, namely $^{222-226}$Ra and $^{224,226}$Th. Significantly, our model demonstrates remarkable agreement with the corresponding experimental data, particularly for the recently determined B(EL) transition rates of $^{224}$Ra, surpassing the performance of the model that employs the Davidson potential. The stability of the octupole deformation in $^{224}$Ra adds particular significance to these findings.

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