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arXiv · 2502.09096

Low-energy spectra of nobelium isotopes: Skyrme random-phase-approximation analysis

V. O. Nesterenko·M. A. Mardyban·A. Repko·R. V. Jolos·P. -G. Reinhard·Alan A. Dzhioev
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Abstract

Low-energy spectra in the isotopic chain $^{250-262}$No are systematically investigated within the fully self-consistent Quasiparticle Random-Phase-Approximation (QRPA) using Skyrme forces SLy4, SLy6, SkM* and SVbas. QRPA states of multipolarity $\lambda\mu$=20, 22, 30, 31, 32, 33, 43, 44 and 98 are considered. The main attention is paid to isotopes $^{252}$No and $^{254}$No where the most extensive experimental spectroscopic information is available. In these two nuclei, a reasonable description of $K^{\pi}=8^-, 2^-$and $3^+$ isomers is obtained with forces SLy4 and SLy6. The disputed $8^-$ isomer in $^{254}$No is assigned as neutron two-quasiparticle configuration $nn[734\uparrow,613\uparrow]$. The isomers are additionally analyzed using Skyrme functionals UNEDF1, UNEDF2 and UNEDF1$^{\rm SO}$. At the energies 1.2 - 1.4 MeV, the 2qp $K$-isomers $4^-, 7^-$ in $^{252}$No and $4^-, 6^-, 7^-$ in $^{254}$No are also predicted. In $^{254}$No, the $K^{\pi}=3^+$ isomer should be accompanied by the nearby $K^{\pi}=4^+$ counterpart. It is shown that, in the chain $^{250-262}$No, some features of $^{252}$No and $^{254}$No should exhibit essential irregularities caused by a noticeable shell gap in the neutron single-particle spectrum and corresponding reduction of the neutron pairing. In particular, low-energy pairing-vibrational $K^{\pi}=0^+$ states in $^{252,254}$No are predicted.

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V. O. Nesterenko, M. A. Mardyban, A. Repko, R. V. Jolos, P. -G. Reinhard, Alan A. Dzhioev. 2025-02-13. Low-energy spectra of nobelium isotopes: Skyrme random-phase-approximation analysis. https://doi.org/10.1103/54k6-dvnr

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