TRIUMF, a Canadian laboratory for nuclear and particle physics, recently contributed to the discovery of a previously unknown type of neutrino behavior. During the international experiment Tokai to Kamioka (T2K), researchers observed the transformation of muon neutrinos into electron neutrinos through a process called oscillation. Muon neutrinos were sent to Kamioka from an accelerator facility in Tokai, but the number of electrons that were detected at the Kamioka facility was greater than the number  predicted, indicating that they had been transformed from the muon neutrinos. This particular type of neutrino oscillation had not previously been observed.


Researchers from both the University of Toronto and York University were part of the experiment. A major contribution from the two universities was the Optical Transition Radiation device, which increased the experiment’s precision by tracking the proton beam from which the neutrinos were produced. Other Toronto team members contributed to the collection, analysis, and prediction of data.

In addition to enriching our understanding of nature’s ‘ghost particle,’ the experiment is related to the matter-antimatter symmetry in the universe, one of the most intriguing questions in physics. The results of the T2K experiment suggest the existence of another process: the decay of heavier neutrinos in the early universe. This process, N-decay, is significant as it offers a possible explanation for the relative abundance of matter.

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