The arrival time distribution of EAS at Taro

The arrival time distribution of EAS has been observed since 1995 at Taro cosmicray laboratory (200m above sea level). The EAS arrays consist of 1m² and 0.25m² scintillation detectors, 0.25m² fast timing counters and ultra fast Cherenkov detectors (UFC). 169 0.25m² scintillation detectors are arranged in alattice configuration with a unit distance of 1.5m. UFC is placed at 20m from the center of lattice array. The arrival time distribution has been analyzed with distance from EAS core (r=10-60m). One of the results shows that the radius of corvature increases as shower size (Ne), near to the EAS core.