New results from the K2K experiment

Research output: Contribution to journalArticlepeer-review


The K2K long-baseline neutrino oscillation experiment has analyzed all data including the period ending in February 2004. The total data sample is from 8.9 × 1019 protons on target. We observe 108 events at the far detector, Super-Kamiokande, when 150.9 +11.6 -10.0 were expected. Further, we observe a distortion of the neutrino energy spectrum which is consistent with νμ to ντ oscillation. The probability that we would observe these results if there is no neutrino oscillation is 0.011%, a 3.9 σ significance.

Original languageEnglish (US)
Pages (from-to)3055-3058
Number of pages4
JournalInternational Journal of Modern Physics A
Issue number14
StatePublished - Jun 10 2005

Bibliographical note

Funding Information:
The author wishes to thank the K2K collaboration and all its sponsors, and recognize the effort of the KEK machine group and beam channel group. This work is also supported by the U.S. Department of Energy.


  • Long-baseline
  • Neutrino
  • Neutrino oscillation


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