The analysis of the giant shower observed with the ECC on Mt. Chacaltaya

The giant shower recorded in the ECC channel 18 X-ray film was analysized. This event corresponds to a shower core, which was recorded as a black spot with 1.5 cm diameter. The total observed engergy was estimated to be 3 x 1015 eV, which is about one fourth as small as that of the Andromeda event recorded previously in the ECC channel 14. The distribution of electron density in 10 cascade units of the ECC, the transition curve of total electron number and the lateral distribution of gamma-ray were measured, and their comparison with those of the Andromeda event was made. The comparison indicates that the different nature of nuclear interaction exists between these shower events. (Yoshimori, M.)