Band mixing in 167Er

摘要: Abstract The level structure of 167 Er and the de-excitation mechanism m this nucleus have been studied by radiative capture thermal neutrons in 166 Er. High-resolution measurements gamma-ray spectrum performed using a Ge(Li) anti-Compton spectrometer low-energy region pair for high-energy transitions. Coincidence relationships obtained from with Ge(Li)-NaI(T1) coincidence apparatus. target was 2 O 3 enriched to 95.6 % thus corresponding cross-section contribution (68.8 +5.0 −6.4 ) More than 350 lines detected spectrum. Isotope assignment has achieved comparison spectra those sample natural erbium. high accuracy data results allow construction transition diagram up 1.5 MeV excitation energy. A large number observed energy levels assigned specific configurations their superimposed rotational bands. Detailed analysis suggests considerable mixing between Nilsson states quadrupole vibrations Q 22 , 2−2 20 . Theoretical calculations which take into account correlations, quasiparticle-phonon interaction, rotation-vibration interaction Coriolis coupling. It is shown that neglect correlations leads unreasonable matrix elements. While coupling decisive influence on mechanism, effects due are general small. model predicts individual levels, branching ratios transitions, multipole mixtures partial half-lives. In most cases, good agreement theoretical experimental results. neutron separation found be 436.15 ± 0.48 keV.