T2K

T2K is a long-baseline accelerator neutrino oscillation experiment in Japan, which observes appearance of electron neutrinos in a muon neutrino beam to measure CP violation and other oscillation parameters. Neutrinos are detected at the large-scale water Cherenkov detector Super-Kamiokande, which also makes measurements of atmospheric, solar and supernova neutrinos, as well as providing leading constraints on proton decay.

At the JPARC complex in Japan a beam of muon neutrinos is created and directed toward Super-Kamiokande, 295 km away. Through observing disappearance of muon neutrinos and appearance of electron neutrinos in the beam, neutrino oscillation parameters can be measured. Differences between neutrino and antineutrino oscillations indicate violation of CP symmetry in neutrino physics. Near detectors are used to measure the unoscillated beam, including the ND280 detector, a magnetised tracking detector composed of multiple sub-detectors.

To measure oscillation parameters a precise knowledge of the neutrino interactions is required, these remaining a dominant uncertainty in T2K.  Near detector data is used to make a wide variety of neutrino interaction measurements. Liverpool plays a key role in the T2K cross-section group, producing T2K’s first measurement of Transverse Kinematic Imbalance in the CC1p1p channel, with an upcoming measurement of the CC1p cross section focused on pion kinematics. Such measurements are crucial for understanding neutrino interactions, improving model predictions and reducing oscillation systematics.

Liverpool has a long history of working on the ND280 near detector, with the barrel ECal being built between Liverpool and Daresbury. ND280 has recently been upgraded to enhance its capabilities. Utilising the lower momentum thresholds and neutron tagging abilities we aim to measure interactions producing multiple low momentum nucleons. We also continue to deliver calibrations for the ECal and are developing global particle identification tools.

To make precise measurements of neutrino interactions at Super-K, a good understanding of detector properties is required. To complement existing systems, in 2018 Liverpool led the installation of the UK Light Injection system. This is used for regular monitoring of water quality, showing high sensitivity to changes at the sub-percent level.

Team Leader

  • Professor Neil McCauley

Academic staff:

  • Professor Christos Touramanis
  • Dr Kostas Mavrokoridis
  • Professor Jon Coleman

Research/Technical staff

  • Dr Sam Jenkins
  • Dr David Payne
  • Dr Ellen Sandford
  • Dr Carl Metelko
  • Mr Balint Bogdan

PhD students

  • Mr Patrick Bates
  • Mr Unik Limbu

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