Study of Elementary Particle Phenomena in Early Universe through Observation of Cosmic-ray Antiparticles(The Centenary of the Discovery of Cosmic Rays)

Abstract

It is well known that among cosmic-ray particles, flying from the universe and entering into the earth, very small fraction of antiparticles are contained. Since our universe is matter-dominated, antiparticles naturally produced through elementary particle processes in the universe or remnant from the early universe. Attempts to search for "Antipartcles" among cosmic-ray particles were initiated around 1960's. From then on, many experimental efforts have been made to unveil this rare species, using balloon-borne, satelliteborne, and space station experiments. In this article, we will review the brief history of challenge to observation of rare antiparticles. Recent progress about antiparticle measurement is reviewed.