Observation of ultrahigh energy charged particle by KAMIOKANDE

1988 Fiscal Year Final Research Report Summary

• Project/Area Number: 61540201
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: 核・宇宙線・素粒子
• Research Institution: Niigata University
• Principal Investigator: MIYANO Kazumasa Department of Physics, Niigata University, 理学部, 教授 (10011529)
• Co-Investigator(Kenkyū-buntansha): MIYATA Hitoshi School of Science and Technology, Niigata University, 大学院自然科学研究科, 助手 (80192368)
• Project Period (FY): 1986 – 1988
• Keywords: Charge ratio of cosmic muons / polariztion of cosmic muons / K / pai ratio

Research Abstract

K/pi ratio was deduced by observing stopped mu in the Kamioka detector (KAMIOKANDE-2). 8379 events of the stopped mu and its decay electron (psoitron) was selected from data of the live time of 361 days applying several cuts on the computer.
Reconstruction of real space coordinate of entrance and decay points of mu and direction of the decay electron by using the fitting progrom for Chrenkov rings. mu^+/mu^- ratio was obtained to be 1.3 0.10 from a decay curve which was deduced from a spectrum of time distribution between mu and e events.
Polarization of cosmic mu was obtained to be 0.28 0.09 from the angular distribution of electron (position) in the decay of the cosmic mu. From this polarization, K/pi ratio was deduced to be 0.31 +0.85 -0.31, which was compared with the value obtained in the high energy p-nucleus reaction.