Multiple shape-driving ν(h11/2)2 and π(h11/2)2 alignments in 120Ba

High-spin states have been observed in Ba-120 up to spin 42 (h) over bar. The ground-state band is observed to fork into two aligned two-quasiparticle bands, which are identified with the pi(h(11/2))(2) and nu(h(11/2))(2) quasiparticles. At higher spin in each of the two aligned bands, the other pair of h(11/2) nucleons aligns in each band are observed to align, resulting in the single four-quasiparticle nu(h(11/2))(2) circle times pi(h(11/2))(2) band. This unique and novel phenomenon has allowed interaction strengths and alignment frequencies to be studied and compared. Differences in alignment frequencies, for the same pairs of nucleons are attributed to shape polarization by the aligned or aligning quasiparticles. The interaction strengths have been investigated using a four-band mixing model. The results are discussed with respect to cranked Woods-Saxon calculations, and to alignments in neighboring nuclei. (C) 2000 Elsevier Science B.V. All rights reserved.