Measurement of the probability for gluon splitting into b bbar in Z0 decays

We report a preliminary measurement of the rate of gluon splitting into bottom
quarks, g->b-bbar, in hadronic Z0 decays collected by SLD between 1996 and 1998.
The analysis was performed by looking for secondary bottom production in 4-jet
events of any primary flavor.   A new secondary vertex-reconstruction technique
was applied to each jet  in order to identify b or bbar jets.  The upgraded SLD
CCD-based vertex detector gives very high B-tagging efficiency, especially for B
hadrons of the low energies typical of this process. The two most collinear
tagged b/bbar jets were considered as a g->b-bbar candidate and a neural network
technique was used to remove backgrounds. We measured the rate of secondary
b-bbar production per hadronic event, g_(b-bbar), with a statistical  precision
of 0.7x10^{-3}.