T2K (Tokai to Kamioka), is an international second generation long baseline neutrino experiment, which takes data since the beginning of 2010.
Its main goal is to measure the as yet unknown oscillation parameter θ13, describing the transition between muon and electron neutrinos. Its non-zero value would open a door for studies of CP violation for neutrinos, which many theorists consider to be a very important element in explaining the observed asymmetry between matter and antimatter in the Universe. A higher precision in measuring the mixing angle θ23, describing the oscillations between muon and tau neutrinos, is also very important. Its measured most probable value of 45 degrees corresponds to maximal mixing, which could suggest the existence of a yet unknown symmetry of Nature.
Goal of the T2K experiment are studies of muon neutrino oscillation, especially their change into electron neutrinos and test if neutrinos and antineutrinos oscillate in the same way. Protons accelerated to 30 GeV in J-PARC (Japan Proton Accelerator Research Complex) in Tokai village on the Japanese east coast are used to produce muon neutrinos. Muon neutrino beam with peak energy of 600 MeV after 280 meters goes through a set of two near detectors: INGRID - on the beam axis and ND280 - 2.5° off-axis. Their main purpose is measurement of the beam energy spectrum before oscillation occurs and determination of different neutrino interaction cross-sections. After another 295 km, the beam goes through the far detector Super-Kamiokande located also 2.5° off-axis, in the Mozumi Mine under Mount Ikeno in central Japan. The beam energy was chosen to maximise the probability of neutrino oscillations in the far detector, in which disappearance of muon neutrinos and appearance of electron neutrinos is measured.
Some of most important results of T2K experiments are confirmation (EPS conference, 2013) of electron neutrino appearance in muon neutrino beam with a statistical significance of 7.3$sigma; and indication (KEK seminar, 2017) of CP symmentry violation (CP is a matter-antimatter symmetry) in neutrino sectorat at a confidence level of 2σ (3σ confidence is needed to confirm any result), as well as many measurements of neutrino interaction cross-sections.
Our work concerns ND280 detector and includes studies of neutrino interactions, services for SMRD subdetector and for the upgrade of ND280 detector. People involved in this project are: Agnieszka Zalewska, Tomasz Wąchała, Anna Dąbrowska and Marcela Batkiewicz (contact). Proposed thesis topics, which can be performed in our department are in tab For students.
Participation in this experiment was possible thanks to following projects:
- Harmonia 1, project number: 2011/01/M/ST2/02578, "T2K - eksperyment neutrinowy drugiej generacji"
- Harmonia 6, project number: 2014/14/M/ST2/00850, "T2K - eksperyment neutrinowy drugiej generacji"
- Sonata 9, project number: 2015/17/D/ST2/03533, "Badania oddziaływań neutrin z wykorzystaniem bliskiego detektora eksperymentu T2K"
- Grant z ministerstwa(??)
- This research was also supported by the PL-Grid Infrastructure.
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