Central structure of air showers and large Psub(T)

The air showers with the high energy electromagnetic component were detected by the simultaneous operation of ECC and air shower array in 1971. In order to determine the lateral structure of the particle density, the shower axis was selected at the position having recorded the maximum number of burst particles. The lateral structure is determined with the informations on the shower axis and the incident direction. For the air showers of greater size than 105, the above mentioned method is used, and the shower size and the age parameter are determined. The relation between the determination accuracy of the shower axis and the shower size, the Brown motion of the shower axis and the estimation of P sub(T) are reported. (Yoshimori, M.)