Two-Particle Separation Energy Trends in the Superdeformed Well

Abstract

A measurement of the energy and spin of superdeformed states in 190Hg, obtained through the observation of transitions directly linking superdeformed and normal states, expands the number of isotopes in which binding energies at superdeformation are known. Comparison with neighboring nuclei shows that two-proton separation energies are higher in the superdeformed state than in the normal state, despite the lower Coulomb barrier and lower total binding energy. This unexpected result provides a critical test for nuclear models.

Impact of the surface energy coefficient on the deformation properties of atomic nuclei as predicted by Skyrme energy density functionals

“…The SD bands found for nuclei in the neutron-deficient A ≃ 190 region are of special interest for our analysis, because for some of them the decay-out to ND yrast states occurs at low spins of about 10 , and with only a few intermediate steps that can be resolved in experiment. From the known excitation energies of states in the SD band, the excitation energy of the (unobserved) SD 0 + band-head can be estimated with a good accuracy [70][71][72][73][74][75]. One of these nuclides is 194 Hg.…”

“…The excitation energies are estimated from γ-ray energies of transitions linking SD and ND states and subsequent extrapolation of the SD band to zero spin. For 190 Hg and 194 Hg, the latter has been achieved following discrete transitions [70,75], whereas the estimate for 192 Hg stems from a statistical analysis of a quasi-continuous spectrum [72].…”

“…There are, however, many indications that a satisfactory simultaneous description of nuclear bulk properties and shell structure cannot be achieved with the presently used functional form of the nuclear EDF [17,20,24,81,82]. 188 190 192 194 196 198 200 Mass For ground states they are taken from [84], for SD states from [75].…”

“…This quantity has been discussed earlier in Refs. [75,83]. Results for the S 2n,SD (N, Z) of neutron-deficient Hg and Pb isotopes are compared with the conventional two-neutron separation energies between the ground states S 2n (N, Z) and experimental data for both where available in Figs.…”

“…The authors of Ref. [75] have argued that, compared to the two-particle separation energies of the respective ground states, "Naively, one might expect a reduction in both S 2n and S 2p at superdeformation, since both the binding energies per nucleon and the Coulomb barrier are lower." This, however, is a fallacy.…”