  Sensitivity studies to the CP-violating parameters of the decay Bs->phi phi
with the LHCb experiment are presented. The decay proceeds via a b->s s anti-s
gluonic-penguin quark transition, which is sensitive to contributions from
beyond the Standard Model particles. A time-dependent angular analysis of
simulated data leads to an expected statistical uncertainty of 6 degrees on any
new physics induced CP-violating phase for a sample corresponding to 2 fb^{-1}
of integrated luminosity. The expected precision on sin2beta from the related
decay Bd->phi K0S is also discussed.
