Deformation change at N = 89: Proton inelastic scattering at 12 MeV on /sup 151,152,153/Eu

Scattered protons from /sup 151,152,153/Eu were measured with an Enge split-pole spectrograph at a bombarding energy of 12 MeV. Rotational states up to I/sup π/ = 7- were observed in 152Eu. Values of the deformation parameters were extracted from the scattering data using distorted-wave and coupled-channels techniques. The analysis suggests values of β2 for /sup 151,152,153/Eu to 0.13, 0.28, and 0.28, respectively. For /sup 152,153/Eu β4 is found to be + 0.06. The data for 152Eu suggest that the low-lying members of the K = 4-, [π3/2(411), ν 11/2(505)] band are populated in the (p,p') reaction. This population is consistent with estimates of the degree of Coriolis mixing of this band with the K = 3-, [π5/2(413), ν11/2(505)] ground band