High-spin structures and alignment properties in ¹²⁶Ce

Excited states in ¹²⁶Ce have been observed with the GAMMASPHERE γ-ray detector array, used in conjunction with the MICROBALL charged-particle detector. The reaction ⁶⁴Zn(⁶⁴Zn, xpn α) (beam energy 260 MeV) was used to populate a wide range of nuclei in the neutron-deficient region with A ≈ 120. ¹²⁶Ce was populated via the 2p evaporation channel. The three previously observed bands have been extended to higher spins and some other structures have been identified. The yrast band shows evidence of a delayed neutron alignment occurring at a rotational frequency ω≈0.5 MeV/ℏ as observed in the neighboring odd-/4 nucleus ¹²⁷Pr. One of the two excited bands shows evidence for a similar crossing at a slightly lower frequency and also exhibits a sudden gain in alignment at ω=0.57 MeV/ℏ. The third band may involve the coupling of a γ-vibrational state. All three rotational bands are discussed in terms of standard and extended cranked shell model calculations.