Observation of a (ν72−[514])2 crossing in 180Os

Abstract High-spin states in 180 Os have been populated by means of the 150 Nd( 36 S,6n) reaction at 177 MeV and studied with the γ-spectrometers OSIRIS and GASP. Eight known bands have been extended to higher spins and a new strongly coupled band has been discovered. Configuration assignments of the bands have been carried out in the framework of the tilted-axis cranking model utilizing experimental ratios of reduced transition probabilities B( M1 ) B( E2 ) . The investigation of the alignment behaviour of the bands revealed that besides the well-known first band crossing caused by the alignment of an i 13 2 quasineutron pair, a second band crossing occurs in four of the bands. The crossing frequency is ⩾ 0.38 MeV and the alignment gain is fairly small, ranging between 2 and ⩾4 ℏ;. The crossing can consistently be explained as a two-quasineutron (ν 7 2 − [514]) 2 alignment. This crossing has been observed for the first time.