Indication of Neutrino Transformation Observed

AmiMoJo writes "A Japanese research group says it has observed for the first time an indication that a type of neutrino can change into another type. The group generated a large amount of neutrinos at the Japan Proton Accelerator Research Complex, or J-PARC, in the prefecture's Tokai Village, and aimed them at the Super-Kamiokande observatory in Gifu Prefecture about 300 kilometers away, to look for neutrino oscillation. As a result, the group observed that muon neutrinos can change into electron neutrinos."

proof

[Dr Max]

How do they know they were the same neutrinos they launched out?