Speaker
Description
Reliable estimation of accelerator neutrino beam fluxes is essential for precise neutrino oscillation measurements, particularly in searches for CP violation in the leptonic sector. In long-baseline neutrino experiments, uncertainties in the neutrino flux represent one of the dominant contributions to the total uncertainty on oscillation parameters. The largest component of the flux uncertainty originates from limited knowledge of hadron production in proton–nucleus interactions.
The NA61/SHINE is a fixed-target experiment at the CERN Super Proton Synchrotron and provides precise hadron production measurements for accelerator-based neutrino experiments. For the T2K experiment, NA61/SHINE has performed measurements using a replica target that has the same length, diameter, and material as the actual T2K graphite target. In 2010, high-statistics data for charged hadrons were collected with this replica target, and the resulting measurements reduced the uncertainties in the muon and muon antineutrino flux predictions in T2K to about 5%. To further reduce the systematic uncertainties associated with the neutrino beam, improved knowledge of neutral kaon and lambda production is required. Neutral kaons are the dominant source of the intrinsic electron neutrino component that contaminates the predominantly muon neutrino beam, while lambda hyperons contribute to the muon neutrino flux through their decay chains and secondary interactions. However, previous data samples were not sufficient to achieve the required precision for these measurements. In 2022, NA61/SHINE performed an additional data-taking campaign with the T2K replica target, collecting approximately ten times more statistics than in the earlier measurements.
This contribution describes the current status of the analysis of neutral kaon and lambda production using the 2022 high-statistics replica target data, and outlines the analysis progress and future plans toward providing improved hadron production inputs for accelerator-based neutrino experiments.