High-Spin States in ¹⁴¹Pm

The high-spin states of ¹⁴¹Pm nucleus have been studied by using in-beam ?-ray spectroscopy technology through the ¹²⁶Te(¹⁹F, 4n) reaction at a beam energy of 90 MeV. The previous level scheme has been extended with spin up to 49/2 ?. Many new levels and transitions are identified. Five collective band structures are observed. Based on systematic comparison with the neighboring nuclei, two bands with strong ?I = 1 M1 transitions inside the bands are proposed as the oblate bands with γ ~ -60°, and three bands with large signature splitting have been suggested as the oblate-triaxial deformation with γ ~ -90°. The characteristics for these bands have been discussed.