  The 100 % polarized photon beam at the High Intensity gamma-ray Source (HIgS)
at Duke University has been used to determine the parity of six dipole
excitations between 2.9 and 3.6 MeV in the deformed nuclei 172,174 Yb in photon
scattering (g,g') experiments. The measured parities are compared with previous
assignments based on the K quantum number that had been assigned in Nuclear
Resonance Fluorescence (NRF) experiments by using the Alaga rules. A systematic
survey of the relation between gamma-decay branching ratios and parity quantum
numbers is given for the rare earth nuclei.
