  We present measurements of the top-antitop production cross section in
b-tagged lepton + jets events from proton-antiproton collisions at 1.96 TeV
using the CDF detector at Fermilab. B-jets are tagged with either a secondary
vertex algorithm, or a soft lepton tagger that identifies muons from B hadron
semileptonic decays. With Tevatron Run II data, we estimate the top-antitop
signal fraction in two different ways: by estimating the various background
contributions, and by fitting directly the leading jet transverse energy
spectrum for the signal and background contributions. A subset of the sample
with two secondary vertex tagged jets yields a production cross section
consistent with the inclusive measurements. Results are consistent with a
Standard Model top-antitop signal and current measurements of the top quark
mass.
