Quadrupole moment of the yrast superdeformed band in 192Pb

The lifetimes of states with spins 26ℏ⩾I⩾18ℏ in the yrast superdeformed band of 192Pb have been measured using the Doppler shift attenuation method. The results are consistent with a constant quadrupole moment 〈Q0〉=19.6−0.4+0.5(stat)±2.0(sys) eb. This result is comparable with the values obtained for SD bands in Pb isotopes with N⩾112, but could also be consistent with the smaller quadrupole moment measured in 193Pb. Reasons for the apparently lower deformation of SD 193Pb (compared to its heavier neighbours) are considered in the light of total Routhian surface calculations, and the question of whether a similarly reduced deformation should be expected in 192Pb is addressed.