The T2K Neutrino Flux Prediction

Abstract

The Tokai-to-Kamioka (T2K) experiment studies neutrino oscillations using an o -axis muon neutrino beam with a peak energy of about 0.6 GeV that originates at the J-PARC accelerator facility. Interactions of the neutrinos are observed at near detectors placed at 280 m from the production target and at the far detector { Super-Kamiokande (SK) { located 295 km away. The

ux prediction is an essential part of the successful prediction of neutrino interaction rates at the T2K detectors and is an important input to T2K neutrino oscillation and cross section measurements. A FLUKA and GEANT3 based simulation models the physical processes involved in the neutrino 3 production, from the interaction of primary beam protons in the T2K target, to the decay of hadrons and muons that produce neutrinos. The simulation uses proton beam monitor measurements as inputs. The modeling of hadronic interactions is re-weighted using thin target hadron production data, including recent charged pion and kaon measurements from the NA61/SHINE experiment. For the rst T2K analyses the uncertainties on the ux prediction are evaluated to be below 15% near the ux peak. The uncertainty on the ratio of the ux predictions at the far and near detectors is less than 2 % near the ux peak