  Velocity profiles in a wormlike micelle solution (CTAB in D2O) are recorded
using ultrasound every 2 s after a step-like shear rate into the shear-banding
regime. The stress relaxation occurs over more than six hours and corresponds
to the very slow nucleation and growth of the high-shear band. Moreover,
oscillations of the interface position with a period of about 50 s are observed
during the growth process. Strong wall slip, metastable states and transient
nucleation of three-band flows are also reported and discussed in light of
previous experiments and theoretical models.
