Fast nuclear rotation and octupole deformation

The Sm-150 nucleus has been studied to high spins in a measurement of gamma radiation following the Xe-136 (O-18,4n) Sm-150, compound-nucleus reaction at beam energy of 76 MeV. The measurement was performed at NBI Riso using the NORDBALL array. Alternating parity, epsilon = +1 band in Sm-150 has been observed up to spin I = 22. This band is crossed by two aligned bands, corresponding to a reflection-symmetric shape. After the second crossing the s = +1 band ends abruptly, suggesting that the octupole shape vanishes in Sm-150 above spin I = 22, as predicted by calculations. Other explanations, assuming continuation of the s = +1 band past the two alignments are also discussed.