THE LATERAL DISTRIBUTION OF EXTENSIVE AIR SHOWERS PRODUCED BY COSMIC-RAYS ABOVE 10(19) EV AS MEASURED BY WATER-CERENKOV DETECTORS

Measurements of the lateral distribution function (Idf) of Extensive A ir Showers (EAS) as recorded by the array of water-Cerenkov detectors at Haverah Park are described, and accurate experimental parameterizat ions expressing the mean Idf for 2 x 10(17) <E <4 x 10(18) eV, 50 <r < 700 m, and theta <45 degrees are given. An extrapolation of these rela tions to the regime E greater than or equal to 10(19) eV and r >700 m is described: extrapolation in this energy domain appears valid, and a n approximate correction term is given for the larger core distances. The results of recent Monte Carlo simulations of shower development an d detector behavior are compared to the parameterized Idf. The agreeme nt is good increasing confidence that these simulations may be trusted as design tools for the Auger project, a proposed 'next generation' d etector system. (C) 1997 Elsevier Science B.V.