With the CDF detector at the Tevatron ppbar collider the time
integrated and flavour averaged BBbar mixing parameter chi bar has been
measured to be 0.118 \pm 0.008 \pm 0.020 and 0.118 \pm 0.021 \pm
0.026 using e mu and mu mu data, respectively.  A limit on the CP
violation parameter epsilon_B has also been derived.