SHOWER SIMULATION - LESSONS FROM MOCCA

The paper describes one approach to the Monte-Carlo simulation of exte nsive air showers of energy in the range 10(12) to 10(21) eV, using th in sampling for particles of energy much below the energy of the prima ry particle. Experience of this approach using the MOCCA program is ou tlined. Also, it is argued that only a few features of hadronic intera ctions are important in determining shower properties, and that the fa r plateau region of particle production is of little importance, and h ence a simplified hadron interaction algorithm, as employed in MOCCA, is useful. Methods of demonstrating the contribution of different feat ures of the interactions to observable aspects of showers are illustra ted. The importance of secondary spectra from pion-air collisions in i nfluencing the depth of maximum is highlighted.