Longitudinal Distribution of Čerenkov Light from Extensive Air Showers

The longitudinal development of extensive air showers of ∼${10}^{13}$ eV is studied both experimentally and theoretically. The risetime and duration of Čerenkov pulses in uv light at 3500 m above sea level are studied experimentally with high-speed techniques. The results are in quite good agreement with an accurate Monte Carlo estimate in the $B"$ approximation of electromagnetic shower theory.