The energy spectrum of primary cosmic rays estimated by using the arrival time spread of air shower particles

The primary energy of cosmic rays in the energy region above 1016 eV has been studied with the use of a compact extensive air shower (EAS) array which consists of 8 scintillation counters in 200m2 area. We report on the simulation results for estimating the primary energy and its spectrum by using Linsley's method, and on the improvement of the determination accuracy of the primary energy by applying the zenith angle restricted observation of EAS muons with the new array as well as a brief description of the apparatus.