Multiple shape-driving nu(h(11/2))(2) and pi(h(11/2))(2) alignments in Ba-120

High-spin states have been observed in Ba-120 up to spin 42 (h) over bar. T he 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) qua siparticles. At higher spin in each of the two aligned bands, the other pai r 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 a nd alignment frequencies to be studied and compared. Differences in alignme nt frequencies, for the same pairs of nucleons are attributed to shape pola rization by the aligned or aligning quasiparticles. The interaction strengt hs have been investigated using a four-band mixing model. The results are d iscussed with respect to cranked Woods-Saxon calculations, and to alignment s in neighboring nuclei. (C) 2000 Elsevier Science B.V. All rights reserved .