Measurements of the charge ratio and polarization of cosmic ray muons with the Super-Kamiokande detector

Abstract

Cosmic-ray muons arise from the showers of secondary particles produced via the interactions of primary cosmic particles with air nuclei at the top of the atmosphere. The interaction products, pions and kaons composing showers mostly decay to muons reflect the details of the hadronic interactions depending on their energy. Measurements of the charge ratio and polarization of cosmic-ray muons can be used to constrain high energy hadronic interaction models in the atmosphere. In this presentation, we will report the current status of the measurement of the charge ratio using data collected by the Super-Kamiokande (SK) detector located at a depth of 2700 m of water equivalent. Using the data taken in the fourth phase of SK (SK-IV), the charge ratio is measured to be 1.42\n±\n0.02 (statistical uncertainty only), at the energy of 1.3 TeV. This result for the charge ratio is in good agreement with those previously obtained by deep underground experiments.