Collective bands and lifetime measurements in137Pm

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Abstract
Low-lying states in 137Pm have been investigated using the reactions 122Te(19F,4n)137Pm and 108Pd(32S,p2n)137Pm. Some new energy levels are reported and mean lifetimes have been measured. The second h11/2 proton crossing has been observed in the yrast band, whilst the first h11/2 proton crossing has been observed in the three quasiparticle positive-parity sidebands. There is also some evidence for the first h11/2 neutron alignment. The deformation deduced for the lowest measurable level agrees reasonably well with the predicted ground-state value. However it appears that a fairly smooth increase in deformation occurs between 133Pm and 135Pm, rather than an abrupt change between 135Pm and 137Pm predicted by the calculations.