The lateral distribution of extensive air showers produced by cosmic rays above 10¹⁹ eV as measured by water-Čerenkov detectors

Measurements of the lateral distribution function (ldf) of Extensive Air Showers (EAS) as recorded by the array of water-Čerenkov detectors at Haverah Park are described, and accurate experimental parameterizations expressing the mean ldf for 2 × 10¹⁷ < E < 4 × 10¹⁸ eV, 50 < r < 700 m, and θ < 45° are given. An extrapolation of these relations to the regime E ≥ 10¹⁹ eV and r > 700 m is described: extrapolation in this energy domain appears valid, and an approximate correction term is given for the larger core distances. The results of recent Monte Carlo simulations of shower development and detector behavior are compared to the parameterized ldf. The agreement is good increasing confidence that these simulations may be trusted as design tools for the Auger project, a proposed 'next generation' detector system.