Search for Long-Lived Massive Particles and Time Structure of Electrons in Extensive Air Showers

Abstract

An experiment to observe accompanied showers delayed relative to the bulk of extensive-air-shower particles near the core was carried out by using plural detectors set at separate places. Four delayed events hitting two or more detectors at the same time were observed. It is difficult to explain these events by accidental coincidence or conventional processes. However, these events can be explained, provided that a parent particle producing the delayed shower has a lifetime of the order of 1×10⁻⁶ s and is heavier than a nucleon. The thickness of air shower disk was also measured at core distances less than 50 m.