Analysis of the double-core phenomenon in air shower

The research on the double-core phenomenon in air shower has been forwarded worldwidely in connection with the confirmation of the existence of large transverse momentum (large Pt) in nucleon-nucleon interaction. However, there is the difference in frequency itself of the double-core air shower observed by various groups. The causes for this may be the difference in the types of measuring instrument, and the difference in the definition of sub-core (the basis for selecting the double core). These two causative factors have been studied. Spark chambers and scintillation counters, as visible and non-visible instruments respectively, were used simultaneously at the top of Mt. Norikura in 1972, to observe the double core phenomenon. The results of study on the double core problem, based on the data obtained, are described. (Mori, K.)