2025/02/13 by Nesterenko, V. O., Mardyban, M. A., Repko, A. +3
#FOS: Physical sciences #Nuclear Theory (nucl-th)
paper · doi:10.48550/arxiv.2502.09096
Low-energy spectra in the isotopic chain 250-262No 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 λμ=20, 22, 30, 31, 32, 33, 43, 44 and 98 are considered. The main attention is paid to isotopes 252No and 254No where the most extensive experimental spectroscopic information is available. In these two nuclei, a reasonable description of Kπ=8-, 2-and 3+ isomers is obtained with forces SLy4 and SLy6. The disputed 8- isomer in 254No 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 252No and 4-, 6-, 7- in 254No are also predicted. In 254No, the Kπ=3+ isomer should be accompanied by the nearby Kπ=4+ counterpart. It is shown that, in the chain 250-262No, some features of 252No and 254No 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 Kπ=0+ states in 252,254No are predicted.