  Results are presented from a search for heavy bottom-like quarks,
pair-produced in pp collisions at sqrt(s) = 7 TeV, undertaken with the CMS
experiment at the LHC. The b' quarks are assumed to decay exclusively to tW.
The b' anti-b' to t W(+) anti-t W(-) process can be identified by its
distinctive signatures of three leptons or two leptons of same charge, and at
least one b-quark jet. Using a data sample corresponding to an integrated
luminosity of 4.9 inverse femtobarns, observed events are compared to the
standard model background predictions, and the existence of b' quarks having
masses below 611 GeV is excluded at 95% confidence level.
