Two-quasiparticle states in 168Er

摘要: Abstract The level structure of 168Er and the de-excitation mechanism in this nucleus have been studied by radiative capture thermal neutrons samples natural erbium which give a cross-section contribution 89.8±2.3 % for 167Er. Interference from 9.1±2.1 166Er was well known separate study with enriched samples. Highresolution measurements γ-ray spectrum performed using Karlsruhe Ge(Li) anti-Compton spectrometer below 2 MeV double-escape above 5.16 MeV. high accuracy data allows construction considerably extended transition diagram up to excitation energy. A large number new levels has assigned specific configurations their superimposed rotational bands. Conclusive evidence is given that previously states at 1094 keV 1542 are two-quasiparticle neutron [633 ↑ + 524 ↓]nn [633↑−521↓]nn, respectively. Some aspects corresponding log ft values discussed detail. Rotational bands 1354 keV, 1569 be identified Kπ = 1−,2− 3− octupole vibrational properties 1− state presumably close those [512 ↑–633↓]nn. member 0− band probably occurs 1914 keV. simple model pairing plus state-independent force provides surprisingly good microscopic description energies. first 0+ established occur 1217 Within quadrupole spin-quadrupole one obtains interaction constants kq 5.3 kt 8.8 (in units − 1 3 h ω 0 ). [521↓ 642 ↑]nn tentatively 1893 some other more or less collective discussed. No positive found occurrence proton 1820 separation energy determined 7771.24 ±0.48