T2K presents hint of CP violation by neutrinos

The international T2K Collaboration strengthened its previous hint that the symmetry between matter and antimatter may be violated for neutrino oscillation.  A preliminary analysis of T2K’s latest data rejects the hypothesis that neutrinos and antineutrinos oscillate with the same probability at 95% confidence (2σ) level. With nearly twice the neutrino data in 2017 compared to…

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T2K beam run extension given Stage-1 Status at J-PARC

On 30 Sep, 2016, the KEK-IPNS Director and J-PARC Center Director granted stage-1 status to the T2K collaboration’s proposal for an extended beam data run to search for CP violation by neutrinos.  The proposal requests delivery of 20×10²¹ protons-on-target (POT) by 2026, which would allow the possibility of  3 sigma sensitivity for CP violation. In…

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First T2K CP violation search published

T2K’s first search for violation of charge-parity symmetry (CP violation) was published in Physical Review Letters as an Editors Suggestion in the April 14 edition.  This is the first result from T2K that simultaneously analyses both neutrino and antineutrino data sets. The international  T2K (Tokai-to-Kamioka) collaboration searches for CP violation with both neutrino and antineutrino beams,…

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J-PARC delivers 2.0e21 protons on target

On March 2, the number of protons delivered to the neutrino target of the T2K experiment by the J-PARC accelerator reached an important milestone: 2×10^21 accumulated since January 2010.  Many thanks are due to the J-PARC directorate and the staff members for their outstanding work to make this possible ! The protons are produced by the J-PARC…

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Koichiro Nishikawa wins 2016 Pontecorvo Prize

Professor Koichiro Nishikawa has been awarded the Bruno Pontecorvo Prize for the year 2016. The Bruno Pontecorvo Prize is awarded by the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, for elementary particle physics. The prize commemorates Prof. Bruno Pontecorvo, a pioneering neutrino physicist who worked for many decades at JINR. The Prize was…

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T2K実験

T2K(Tokai to Kamioka)実験は、ニュートリノが飛行中どのように変化するか(ニュートリノ振動)を研究するために設計されたニュートリノ振動実験です。茨城県那珂郡東海村にあるJ-PARC(大強度陽子加速器施設)内で、大強度のミューニュートリノが生成され、295km離れた岐阜県飛騨市神岡町の山中にあるニュートリノ検出器スーパーカミオカンデに打ち込まれます。ニュートリノビームはJ-PARCのサイトを離れる前に前置検出器(ND280)で一度測定され、そして再びスーパーカミオカンデで強度と世代の変化を測定することによって、ニュートリノの性質を調べます。

Map showing J-PARC and Super-K

T2Kにおける科学的目的

  • ミューニュートリノから電子ニュートリノへ変化する出現事象の発見 (未知の混合角θ13の確認)
  • ミューニュートリノ消失の振動パラメータの精密測定
  • 中性カレント事象観測によるミューオンニュートリノ欠損におけるステライル成分の探索
  • ニュートリノ-原子核反応断面積の高精度測定に対する世界をリードする貢献