IS THERE EXPERIMENTAL-EVIDENCE FOR AN INTERPRETATION OF THE LOWEST K=0 COLLECTIVE EXCITATION OF DEFORMED-NUCLEI AS A PHONON EXCITATION OF THE GAMMA-BAND

The experimental evidence presented recently by Casten and von Brentan o, to;support their suggestion that the lowest excited K-pi=O+ states in deformed nuclei should be given a new interpretation as a phonon bu ilt on the gamma vibration, is critically examined. It is argued that in the determination of B (E2,0(beta)(+)--> 2(gamma)(+)) values from t he higher-spin members of the beta band to the gamma band the rotation al transitions caused by the mutual coupling of the beta and gamma ban ds have to be taken into account. An intensity limit is obtained for t he O-beta(+)-->2(gamma)(+) gamma transition in Dy-160 yielding B(E2,0 (+)(beta)-->2(gamma)(+))/B(E2,0 (+)(beta)-->2(g)(+))less than or equal to 25. We conclude that there is no experimental evidence supporting the new interpretation of the beta vibrations in the deformed rare-ear th nuclei.