Lifetimes of low-spin members of the superdeformed band in ${}_{}{}^{135}{}_{}{}^{}\mathrm{Nd}$ have been determined by the Doppler-shift recoil-distance method. We find a quadrupole moment of 7.$2_{\mathrm{-}1.5}^{+1.2\mathrm{}}$ b for the 677 keV (37/2- 33) / 2 ) transition in the band, confirming the large deformation previously measured by the Doppler-shift attenuation method. However, the quadrupole moment for the 620 keV transition deexciting the 3.324 MeV (25/2) state at the bottom of the band is much smaller. We conclude that the superdeformed potential-energy minimum disappears or the band drastically changes character at this point which causes the sudden depopulation.

• Received 22 March 1993

DOI:https://doi.org/10.1103/PhysRevC.48.R494