Evidence of high- K isomerism in No154102256

Abstract

Isomeric states in $^{256}\mathrm{No}$ were investigated using internal conversion electron and $\ensuremath{\gamma}$-ray spectroscopy with the GABRIELA detection system at the focal plane of the SHELS recoil separator, at the Flerov Laboratory for Nuclear Research (FLNR, JINR, Dubna). The nuclei of interest were produced using the highly asymmetric fusion-evaporation reaction $^{238}\mathrm{U}(^{22}\mathrm{Ne},4n)^{256}\mathrm{No}$. The emission of internal conversion electrons and $\ensuremath{\gamma}$ rays occurring between a $^{256}\mathrm{No}$ implantation and a subsequent $\ensuremath{\alpha}$-decay event were studied, resulting in the observation of high-$K$ isomerism in this nobelium isotope. The nature of the isomeric states is discussed in terms of possible two- and four-quasiparticle structures.