Loss of alignment gain in the πh 9/2[541 1/2−] ⊗ (νi 13/2)2 band in 167Tm and neighbouring odd-Z N = 98 nuclei

Theπh_9/2[541 1/2^?] band in ¹⁶⁷Tm has been studied through the ¹²⁴Sn(⁴⁸Ca, p4n)¹⁶⁷Tm reaction at E _beam = 210 MeV. The favoured signature of the πh_9/2[541 1/2^?] band is observed to spin 61/2h?. A remarkable small gain in aligned angular momentum at the AB-band crossing has been found. The crossing frequency and the gain in aligned angular momentum for ¹⁶⁷Tm are compared with data for the N = 98 isotones of Lu, Ta and Re, and contrasted with Cranked Shell Model predictions, based on frequency diabatic configurations. Large deviations are found for the gain in aligned angular momentum.     

High-K multi-quasiparticle states in No

We report results from an experiment on the decay of the high-K isomers in ²⁵⁴No. We have been able to establish the decay from the known high-lying four-quasiparticle isomer, which we assign as a Kπ=¹⁶⁺${\mathrm{K}}^{\pi }={16}^{+}$ state at an excitation energy of Ex=2.928(3) MeV${\mathrm{E}}_x=2.928(3)\text{MeV}$. The decay of this state passes through a rotational band based on a previously unobserved state at Ex=2.012(2) MeV${\mathrm{E}}_x=2.012(2)\text{MeV}$, which we suggest is based on a two-quasineutron configuration with Kπ=¹⁰⁺${\mathrm{K}}^{\pi }={10}^{+}$. This state in turn decays to a rotational band based on the known Kπ=⁸⁻${\mathrm{K}}^{\pi }=8^{-}$ isomer, which we infer must also have a two quasineutron configuration. We are able to assign many new gamma-rays associated with the decay of the Kπ=⁸⁻${\mathrm{K}}^{\pi }=8^{-}$ isomer, including the identification of a highly K-forbidden ΔK=8$\mathrm{\Delta }\mathrm{K}=8$ E1 transition to the ground-state band. These results provide valuable new information on the orbitals close to the Fermi surface, pairing correlations, deformation and rotational response, and K-conservation in nuclei of the deformed trans-fermium region.