On the Structure of Extensive Cosmic Ray Air Showers: Lateral Structure of the Ionizing Component

The lateral distribution of ionizing particles in extensive showers over the approximate range of size 5 × 104 < N < 5 × 105 particles has been studied using a core-locating device (already described) to select showers, and unshielded `probing' counter trays to estimate particle density at measured distances from the located shower axis. The distribution is determined with useful accuracy for four ranges of shower size. For the three greatest size ranges examined, the distribution is generally in accord with that of other workers and confirms the observation that for these showers structure does not vary significantly with shower size. For the range corresponding to the smallest showers, which are of a size for which accurate structure measurements have not previously been reported, it is found that the lateral structure shows evidence of significant ageing of the effective cascade.