Gigantic gamma-ray family events with ΣEγ≥1000 TeV and hadronic interactions

The characteristic features of big family events with ΣEγ≥103 TeV, which were observed with emulsion chambers at Mt. Fuji (3776 m above sea-level), are presented in comparison with the results of the Monte Carlo simulation. Moreover, the behaviour of the halo accompanying big family events is described in connection with that of high-energy gamma-rays incident upon the chamber. On the basis of the experimental data, some inferences about the hadronic interactions at energies around 104 TeV are discussed. The general tendency of our data does not seriously contradict the scaling prediction if the primaries are adequately mixed with heavy nuclei. In this case, the cross-sections should increase rapidly with energy up to 104 TeV at least. There exist no clear signs showing a rapid increase of the average transverse momentum.