A Measurement of the Time Dependence of B_d-B(bar)_d
Mixing  Using Kaon Tagging

The SLD Collaboration


We report a preliminary measurement of the time dependence of
B_d- B(bar)_d mixing using a sample of 400,000 hadronic 
Z^0 decays collected by the SLD experiment at the SLC.  B decay vertices are 
reconstructed inclusively with a topological technique and the B hadron flavor
at production is determined by exploiting the large forward-backward 
asymmetry of polarized Z^0 ->  bb-bar decays in combination with 
information from the hemisphere opposite that of the  reconstructed B decay.
The flavor of the B hadron at decay is provided by the charge of kaons
attached to the B decay vertex and identified with the Cherenkov Ring Imaging
Detector.  The measurement of the oscillation frequency allows the 
determination of delta(m_d) with a statistical accuracy of ~ 0.03 ps^-1.