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P. L. Sassarini

Publications and source records attributed to P. L. Sassarini.

3 recordsLinked to original sources

Electromagnetic moments of ground and excited states calculated in heavy odd-N open-shell nuclei

Within nuclear DFT, we calculated spectroscopic magnetic dipole and electric quadrupole moments for various quasiparticle configurations of odd-$N$, even-$Z$, $83\leq{}N\leq125$ nuclei ranging from gadolinium to osmium. By tagging the blocked quasiparticles with single-particle states of the semi-magic dysprosium isotope, we efficiently computed 22 prolate and 22 oblate states for each of the 154 nuclei and tracked them across the entire major neutron shell. We compared this extensive set of theoretical results with experimental data for 82 states in the region. Breaking rotational, time-reversal, and signature symmetries, we aligned the intrinsic angular momenta along the axis of axial symmetry, thereby enabling full shape- and spin-self-consistent polarizations. The spectroscopic moments were then obtained by restoring rotational symmetry. We conducted a detailed analysis of the pattern of agreement and disagreement between theory and experiment in individual nuclei. For the magnetic dipole moments, agreement with the data varies and is characterized by an overall average and RMS deviation of 0.11 $μ_N$ and 0.35 $μ_N$, respectively. For the electric quadrupole moments, a good corresponding agreement of 0.16 b and 0.29 b was observed.

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Seniority-two valence-shell building blocks of the octupole phonon

The relative ordering of $J^-$ levels of multiplets resulting from two-body excitations, which include a $J^π=3^-$ state that can contribute to the octupole phonon, are investigated in a simplistic shell-model approach. To calculate the relative level ordering, harmonic oscillator wavefunctions and a residual $δ$ interaction are used. The simplistic approach confirms for the particle-particle channel, the often stated preference of the $Δj=3, Δl =3$ subshell combination over the $Δj=3, Δl =1$ subshell combination through an enhanced energy gain. Furthermore, it is shown that, in the particle-hole channel, the gain is less pronounced for the $Δj=3, Δl =3$ subshell configuration. In combination with the overall structure of an oscillator shell, these results explain the comparatively low excitation energy for 3$^-_1$ excitations observed for the octupole-soft proton and neutron numbers predicted by various models.

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Nuclear DFT analysis of electromagnetic moments in odd near doubly magic nuclei

We use the nuclear density functional theory to determine nuclear electric quadrupole and magnetic dipole moments in all one-particle and one-hole neighbours of eight doubly magic nuclei. We align angular momenta along the intrinsic axial-symmetry axis with broken time-reversal symmetry, which allows us to explore fully the self-consistent charge, spin, and current polarisation. Spectroscopic moments are determined for symmetry-restored wave functions and compared with available experimental data. We find that the obtained polarisations do not call for using quadrupole- or dipole-moment operators with effective charges or effective g-factors.

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