Neutrino production of same-sign dimuons

In a sample of 670 000 charged-current neutrino events, 101 μ^-{{μ}}^{{{-}}}$ events have been observed, with 30 GeV${E}_{{ν}}$600 GeV and ${P}_{{μ}}$>9 GeV/c for both muons. After background subtraction, 18.5±{}13.9 events remain, yielding a prompt rate of (5.5±{}4.1)×{}10^-5 per charged-current event. A sample of 124 000 antineutrino events yields 15 μ⁺{{μ}}⁺events, giving 6.4±4.2 events after background subtraction and a prompt rate of (1.0±0.7)×{10}^{{{-}}4}$ per charged-current event. The numbers and kinematic distributions of these events are consistent with standard model sources.