Fonctionne avec Indico
v3.2.8
The T2K experiment is a long baseline neutrino oscillation experiment whose current goal is to observe CP violation in the lepton sector. It is operating in Japan, using the 0.6 GeV muon-neutrino beam produced by J-PARC accelerator complex and aiming at Super-Kamiokande. As in most long baseline experiments, sensitivity is limited by systematical uncertainites on the modelling of neutrino-nucleus interactions ; this is due to nuclear effects such as nucleons correlations or final state interactions. A large effort has thus been made inside the collaboration to acurately measure various neutrino-nucleus interaction channels. In order to provide such important measurements, the WAGASCI detector – a lattice of scintillator bars in a water tank – has been installed as a new Near Detector in 2016 at J-PARC.
As an example, we will present the measurement of the charged-current νμ - nucleus cross section, with one associated charged pion in the final state (CC1π channel) : this channel is the main background in the oscillation analysis. The measurement has been performed with the first module of the WAGASCI detector, allowing for a measurement on a water target (similar to that of the Far Detector Super-Kamiokande). We will present the steps leading to this analysis, from the assembly and commissionning of the detector to the cross-section extraction. This results – and many others – are used to improve the sensitivity on the CP-violating phase : the value δCP = 0° is now excluded at the 3σ level by the T2K experiment.