Isomers and hindrances in ²⁵⁴No (Z=102)

The physics and chemistry of superheavy elements are frontier areas of current research.

While elements up to Z=118

have been synthesized, detailed spectroscopic investigations are feasible mainly for

nuclei around Z≈100. These axially deformed nuclei exhibit long-lived isomers

from valence nucleon couplings, providing insights into nuclear structure and

symmetries. We report on a new spectroscopic study of the decay of high-K

isomers in ²⁵⁴No₁₅₂, a touchstone nucleus for testing models for the structure

of superheavy nuclei. The experiment, performed using the Argonne Gas-Filled

Analyzer (AGFA), was geared toward resolving long-standing ambiguities in spin-

parity and configuration assignments for the two- and four-quasiparticle (qp)

intrinsic excitations identified in this nucleus. The isomer decay schemes are

firmly established with the help of the highest-statistics γ-γ coincidence data

collected to date, providing anchor points for competing theories. The results

will be presented and compared to existing model predictions, and new insights

for distinguishing between hindrances arising from the K quantum number or

from other configuration changes will be discussed