（5月28日） Yuuki Nakano 助理教授：Measurements of the charge ratio and polarization of cosmic-ray muons with the Super-Kamiokande detector
报告人:
Yuuki Nakano 助理教授（日本富山大学）
题目:
Measurements of the charge ratio and polarization of cosmic-ray muons with the Super-Kamiokande detector
地点：
哲生堂405会议室
时间:
2026年5月28日15:00
唐健 教授
报告简介：
Neutrinos and muons from cosmic-ray interactions in the atmosphere originate from mesons, such as pions and kaons, in air-showers. An accuracy of the absolute atmospheric neutrino flux and its flavor ratio are limited due to the uncertainty of meson productions in hadronic interaction models. In order to reduce such uncertainty, measurements of the charge ratio and the polarization of cosmic-ray muons are important as new inputs to theoretical models which simulate the atmospheric neutrino flux. In this proceedings, we present the results of the charge ratio (R) and polarization (P^{μ}_{0}) of cosmic-ray muon measurements using the decay electrons collected from 2008 September to 2022 June by the Super-Kamiokande (SK) detector. We measured muon charge ratio to be R=1.32±0.02 (stat.+syst.) and the muon polarization at the production location to be P^{μ}_{0}=0.52±0.02 (stat.+syst.). The SK detector uniquely measured the polarization of cosmic-ray muons with energies more than 1 TeV at sea-level because of its underground location. We also present the branching ratios of unstable isotopes through nuclear muon capture processes with Oxygen.
报告人简介：
2016 March Ph.D. from the University of Tokyo
2016 April -2017 March Posdoc in Kobe university
2017 April -2019 March Posdoc at the institute of cosmic-ray research, the University of Tokyo
2019 April - 2021 August Specially Appointed Assistant Professor at Kobe university
2021 September - 2024 March Specially Appointed Assistant Professor at the institute of cosmic-ray research, the University of Tokyo
2024 April - now Assistant professor at the university of Toyama
