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T2K experiment
T2K ("Tokai to Kamioka") is a particle physics experiment studying the oscillations of the accelerator neutrinos. The experiment is conducted in Japan by the international cooperation of about 500 physicists and engineers with over 60 research institutions from several countries from Europe, Asia and North America and it is a recognized CERN experiment (RE13). T2K collected data within its first phase of operation from 2010 till 2021. The second phase of data taking (T2K-II) is expected to start in 2023 and last until commencement of the successor of T2K – the Hyper-Kamiokande experiment in 2027.
T2K was the first experiment which observed the appearance of electron neutrinos in a muon neutrino beam. It also provided the world best measurement of oscillation parameter θ23 and a hint of a significant matter-antimatter asymmetry in neutrino oscillations. The measurement of the neutrino-antineutrino oscillation asymmetry may bring us closer to the explanation of the existence of our matter-dominated Universe.
The intense beam of muon neutrinos is produced in the J-PARC facility (Japan Proton Accelerator Research Complex) in Tokai on the east coast of Japan. The beam is directed towards the Super-Kamiokande far detector located 295 kilometres (183 mi) away in the city of Hida, Gifu prefecture. The properties and composition of the neutrino flux are first measured by a system of near detectors located 280 metres (920 ft) from the beam production place at the J-PARC site, and then again in the Super-Kamiokande detector. Comparison of the content of different neutrino flavours in these two locations allows measurement of the oscillations probability on the way between near and far detectors. Super-Kamiokande is able to detect interactions of both, muon and electron neutrinos, and thus measure the disappearance of muon neutrino flux, as well as electron neutrino appearance in the beam.
T2K experiment was proposed in 2003 with the following measurement goals:
Since the start of the data taking in 2010, the T2K experiment succeeded to provide a list of world-class results:
δCP takes values from -π to π (i.e. from −180° to 180°) and can be measured by comparing oscillations of neutrinos to those of antineutrinos. The CP symmetry would be conserved, and thus the oscillation probabilities would be the same for neutrinos and antineutrinos, for δCP equal to 0 or ±π. T2K provided the first and the strongest yet constraint on δCP, rejecting at the 3σ (99.7%) significance level almost half of the possible values, ruling out the both CP conserving points at the significance level of 95% and giving a strong hint that CP violation may be large in the neutrino sector. The CP violation is one of the conditions proposed by the Russian physicist Andrei Sakharov, necessary to produce the excess of matter with respect to antimatter at the early universe, which forms now our matter-built Universe. CP violation in quark section was confirmed already in 1964, but it is too small to explain the observed matter-antimatter imbalance. The strong CP violation in the neutrino sector could lead to matter excess production through the process called leptogenesis and thus such measurement would be important step to understand how the Universe were formed.
The NOvA experiment is the other neutrino oscillation experiment capable to measure δCP through the comparison between ν
μ→ν
e and ν
μ→ν
e oscillation channels. NOvA is conducted in the United States and measures accelerator neutrino oscillation at the distance of 810 km on the way between beam production place in Fermilab and far detector in Ash River, Minnesota. NOvA provided a less precise measurement of δCP, which is in slight tension with the T2K result. The T2K best-fit point lies in the region disfavoured by NOvA at the confidence level of 90%. There are ongoing works to obtain a joint fit to data from both experiments to quantify consistency between them.
Future upgrades of T2K is expected to provide more precise measurements of Δm2
23 and θ23 parameters, cross-section measurements which will extend our understanding of neutrino interactions and thus improve theoretical models used in neutrino generators, as well as further constrain on the δCP phase and confirmation if the CP symmetry is conserved or violated in the neutrino oscillation at the 3σ significance level in the T2K-II and 5σ in the Hyper-Kamiokande experiment.
Hub AI
T2K experiment AI simulator
(@T2K experiment_simulator)
T2K experiment
T2K ("Tokai to Kamioka") is a particle physics experiment studying the oscillations of the accelerator neutrinos. The experiment is conducted in Japan by the international cooperation of about 500 physicists and engineers with over 60 research institutions from several countries from Europe, Asia and North America and it is a recognized CERN experiment (RE13). T2K collected data within its first phase of operation from 2010 till 2021. The second phase of data taking (T2K-II) is expected to start in 2023 and last until commencement of the successor of T2K – the Hyper-Kamiokande experiment in 2027.
T2K was the first experiment which observed the appearance of electron neutrinos in a muon neutrino beam. It also provided the world best measurement of oscillation parameter θ23 and a hint of a significant matter-antimatter asymmetry in neutrino oscillations. The measurement of the neutrino-antineutrino oscillation asymmetry may bring us closer to the explanation of the existence of our matter-dominated Universe.
The intense beam of muon neutrinos is produced in the J-PARC facility (Japan Proton Accelerator Research Complex) in Tokai on the east coast of Japan. The beam is directed towards the Super-Kamiokande far detector located 295 kilometres (183 mi) away in the city of Hida, Gifu prefecture. The properties and composition of the neutrino flux are first measured by a system of near detectors located 280 metres (920 ft) from the beam production place at the J-PARC site, and then again in the Super-Kamiokande detector. Comparison of the content of different neutrino flavours in these two locations allows measurement of the oscillations probability on the way between near and far detectors. Super-Kamiokande is able to detect interactions of both, muon and electron neutrinos, and thus measure the disappearance of muon neutrino flux, as well as electron neutrino appearance in the beam.
T2K experiment was proposed in 2003 with the following measurement goals:
Since the start of the data taking in 2010, the T2K experiment succeeded to provide a list of world-class results:
δCP takes values from -π to π (i.e. from −180° to 180°) and can be measured by comparing oscillations of neutrinos to those of antineutrinos. The CP symmetry would be conserved, and thus the oscillation probabilities would be the same for neutrinos and antineutrinos, for δCP equal to 0 or ±π. T2K provided the first and the strongest yet constraint on δCP, rejecting at the 3σ (99.7%) significance level almost half of the possible values, ruling out the both CP conserving points at the significance level of 95% and giving a strong hint that CP violation may be large in the neutrino sector. The CP violation is one of the conditions proposed by the Russian physicist Andrei Sakharov, necessary to produce the excess of matter with respect to antimatter at the early universe, which forms now our matter-built Universe. CP violation in quark section was confirmed already in 1964, but it is too small to explain the observed matter-antimatter imbalance. The strong CP violation in the neutrino sector could lead to matter excess production through the process called leptogenesis and thus such measurement would be important step to understand how the Universe were formed.
The NOvA experiment is the other neutrino oscillation experiment capable to measure δCP through the comparison between ν
μ→ν
e and ν
μ→ν
e oscillation channels. NOvA is conducted in the United States and measures accelerator neutrino oscillation at the distance of 810 km on the way between beam production place in Fermilab and far detector in Ash River, Minnesota. NOvA provided a less precise measurement of δCP, which is in slight tension with the T2K result. The T2K best-fit point lies in the region disfavoured by NOvA at the confidence level of 90%. There are ongoing works to obtain a joint fit to data from both experiments to quantify consistency between them.
Future upgrades of T2K is expected to provide more precise measurements of Δm2
23 and θ23 parameters, cross-section measurements which will extend our understanding of neutrino interactions and thus improve theoretical models used in neutrino generators, as well as further constrain on the δCP phase and confirmation if the CP symmetry is conserved or violated in the neutrino oscillation at the 3σ significance level in the T2K-II and 5σ in the Hyper-Kamiokande experiment.