On the Structure of Extensive Cosmic Ray Air Showers: Core Detection and Core Structure

Abstract

A `core-detecting' apparatus is described for which the efficiency of core detection is uniform for central electron densities from about 20 to 200m-2. Accuracy of location of shower axes has been studied by means of decoherence curves between two identical units; more than 50% of responses are shown to arise from showers for which the axis falls within 3 m of the centre of the detector. The performance of the core detector is shown to be consistent with the conclusion that the proportion of energetic electrons in the centre of showers changes little over the range of shower size examined, and in particular that the smaller showers do not show the characteristics of `old' cascades. The observations provide no evidence of any core structure of size comparable with the measured accuracy of location.