Rotational bands in 170Yb observed following (α,xn) reactions

Abstract

Abstract At least seven side bands, with Kπ = (0+), (1−), (2+), (3−), 4−, 6−, and 7−, have been identified in 170Yb up to high spin, using γ-ray techniques following (α, 2n) and (α, 4n) reactions. Backbending in the positive-parity yrast band is confirmed, and candidates for low-spin members of the S-band are found. The negative-parity yrast band has behaviour characteristic of both strong coupling and decoupling. These properties, together with those in the other negative-parity side bands, are interpreted as arising from Coriolis effects on the quasiparticle configurations, and the experimental results are compared with a two-quasipartiele-plus-rotor calculation. Evidence of ΔK = 2 mixing is found in the K = (3) side band. The relationship between the moments of inertia of the positiveparity and negative-parity yrast bands in the N = 100 isotones is discussed in the framework of a simple empirical model, giving insight into the presence or absence of backbending. The negativeparity yrast bands in the N = 100 isotones are compared. Their significant differences are qualitatively reprodued in two-quasiparticle-plus-rotor calculations.