  We compute the relaxation time for quark/antiquark spin and thermal vorticity
alignment in a quark-gluon plasma at finite temperature and quark chemical
potential. We model the interaction of quark/antiquark spin with thermal
vorticity as driven by a phenomenological modification of the elementary quark
interaction with gluons. We find that in a scenario where the angular velocity
of the quark-gluon plasma produced in a peripheral heavy-ion collision is
small, quarks/antiquarks take a long time to align their spin with the
vorticity. However, when the angular velocity created in the reaction is large,
the alignment is efficient and well within the lifetime of the system created
in the reaction. The relaxation time is larger for antiquarks which points out
to a difference for the polarization of hadrons and antihadrons when this
alignment is preserved during hadronization.
