High spin states and shape coexistence in ¹³⁴Ce

High spin states in ¹³⁴Ce nucleus have been studied by using the heavy-ion induced reaction ¹²²Sn(¹⁶O,4n) carried out at China Institute of Atomic Energy. The early level scheme has been extended with spin up to 22ℏ. However, our result is different from that in a recent publication, and the magnetic rotation bands reported there have not been confirmed. Our observed level structures may be interpreted as shape coexistence. The 10⁺ state at the backbending with h_11/2 quasineutron configuration has an oblate deformation with an asymmetry parameter γ ≈ -60° (Lund convention), and the 10⁺ isomer is a yrast trap of prolate deformation with γ ≈ -120°,whereas the other signature partner bands with h_11/2 and g_7/2 proton configuration probably have a prolate deformation with γ ≈ 0°.