Pair-Production of W Bosons in $e^+ e^-$ Interactions at $\sqrt{s}$ = 161 GeV

We report on the measurement of W-boson pair-production with the L3 detector at LEP at a centre-of-mass energy of 161.34~\GeV. In a data sample corresponding to a total luminosity of 11~pb$^{-1}$, we select four-fermion events with high invariant masses of pairs of hadronic jets or leptons. Combining all final states, the measured total cross section for W-pair production is: $\SWW = 2.89^{+0.81}_{-0.70}~(stat.)\pm0.14~(syst.)$~pb. Within the Standard Model, this corresponds to a mass of the W boson of: $\MW = 80.80^{+0.48}_{-0.42}~(exp.)\pm 0.03$~(LEP)~\GeV. Limits on anomalous triple-vector-boson couplings are derived. \end{abstract}