Transition probabilities between two-quasiparticle configurations in 170, 172Yb and 182W

Abstract

Applying the generalized centroid-shift method in (α, 2n) reactions, the following half-lives of 2q.p. states have been measured: T 1 2 (1375.8 keV) = 0.20 ± 0.07 ns , T 1 2 (1640.8 keV) = 0.5 ± 0.2 ns , T 1 2 (2689.5 keV) = 0.7 ± 0.1 ns ( 172 Yb) ; T 1 2 (2189.9 keV) = 2.2 ± 0.3 ns , T 1 2 (1851.5 keV) < 0.2 ns ( 170 Yb) ; T 1 2 (100.1 keV) = 1.4 ± 0.2 ns , T 1 2 (1809.7 keV) = 0.25 ± 0.10 ns , T 1 2 (1829.5 keV) = 0.25 ± 0.10 ns , T 1 2 (1756.8 keV) < 0.5 ns ( 182 W) . The experimental E1, M1 and E2 transition rates are compared to calculations within the Nilsson-plus-pairing model. The band-head K π = 4 − of a semi-aligned band in 172Yb appears as a deformation-aligned 2q.p. configuration. The E2 transition rates indicate configuration mixing between the 2q.p. K π = 4 −, 5 − and 6 − states in 182W.