Extensive air showers (EASs) accompanied by families of high-energy cascade showers were observed at Mt. Norikura (738 g cm-2). 99 families of -ray- and hadron-origin showers with total energies JE,H10 TeV were obtained. The success rate of the combination between families and EASs reaches to almost 90% (87 events). The families are associated with young EASs, with mean age parameter s0.7, whose sizes distribute widely over three orders of magnitude up to 108. The size spectrum of the family-associated EASs coincides with the general EASs in the size region above 5×106 but the former drops rapidly from the latter below this critical size. From the absolute intensity of JE,H spectrum the proton fraction in the primary cosmic rays is deduced to be (145)%, with an error of one standard deviation, in the primary energies (5×1014)1016 eV, in comparison with a Monte Carlo simulation assuming an adequate interaction model. This agrees with the result obtained by the work with other mountain data and is also compatible with the result inferred from the size spectrum gap between the family-associated EASs and the general EASs in the region below the critical size. 1989 The American Physical Society.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)