Nuclear orientation study of the decay of 169Lu

The level structure of 169Yb and the nature of the linking transitions have been studied by radioactive decay of 169Lu polarised at low temperatures in a gadolinium host. Anisotropies of 112 γ rays in 169Yb have been measured. Unambiguous spin assignments have been made for a number of levels below 2 MeV and multipole mixing ratios of about 90 transitions have been deduced. The energy and structure of individual levels, reduced E2 and M1 transition probabilities and E2:M1 mixing ratios have been calculated using the quasiparticle-phonon model including a Coriolis interaction. In general, good agreement is obtained between the theoretical predictions and the experimental results. (author)