Dimuons Produced by Antineutrinos

In a run with a predominantly $\overline{\nu }$ beam we have observed seven dimuon events which show clearly that dimuons are produced by $\overline{\nu }$ as well as by $\nu$. Using the signature of those events we tentatively identify twelve dimuon events from earlier runs as $\overline{\nu }$-induced. The characteristics of the total sample support the explanation that dimuons arise from new hadron production.