Observation of muon pairs in neutrino interactions at Serpukhov 70 GeV accelarator

A search for dimuons produced in a spark chamber experiment in neutrino and antineutrino beams of the Serpukhov accelerator is reported. The clear dimuon signal has been observed in vN interactions. R v = N (2 ω )/ N (1 ω )⩾ (6.2 ± 1.7) × 10 −3 in the energy interval 7.5 ÷ 30 GeV. From antineutrino data we conclude that in the same energy range R v ⩽ 1.1. × 10 −2 (90% C.L.) .