  This paper summarises the recent results of the Run IIa D0 experiment at the
Tevatron Collider at Fermilab on the observable parameters of the $B_{s}$
meson. A measurement of the branching fraction $B_s->D_s^{(*)}D_s^{(*)}$ is
reported, which provides an estimate of the width difference
$\Delta\Gamma_{s}^{CP}/\Delta\Gamma_{s}$. Through the decay $B_{s} \to J/\psi
\phi$ the width difference $\Delta\Gamma_{s}$ is extracted, and for the first
time a constraint is set on the CP-violating phase $\phi_{s}$, although a
four-fold ambiguity remains. This result is combined with other D0 measurements
to yield $\Delta\Gamma_{s}=0.13\pm0.09 {\rm ps^{-1}}$, $\phi_{s} =
-0.70^{+0.47}_{-0.39}$.
