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An analysis has been made of 2 400 shower cores observed with the 32-m2 neon hodoscope of the Kiel air shower experiment, yielding the following results:1. More than 99% of all showers show a more or less steep single-core distribution.2. The Δ/N distribution (Δ = central density, N = shower size) has a total width of about a factor of 10, showing no appreciable change in that width with increasing shower size in the interval ranging from N = 105 to about 107.3. Only a few double-cored events (4–9) have been found, all of them close to a shower size of 105 particles.4. On the basis of a Monte Carlo simulation of showers initiated by primary particles with different atomic weights, it is concluded that the hypothesis of observed multicored events being due to heavy primaries meets no serious difficulties. However, the cascade process and the associated fluctuations seriously reduce the number of subcores observable; and this reduction effect increases with atomic weight.

Electron density distributions in air shower cores recorded with the 32 m2 neon hodoscope of the Kiel array have been analysed, looking for the existence of significant multicores which might result from large transverse momentum emission of high energy particles. The shower sizes are between 104 and 5×106 particles, corresponding to primary energies up to a few times 107 GeV. Several spurious effects simulating multicores have been found, but there are no indications for the existence of large transverse momenta.

Details on the construction and the performance characteristics of a 31 m2 neon hodoscope are presented. The detector is in operation at Kiel since 1965 investigating the density distribution of charged particles in the cores of extensive air showers. It is shown that a device of this type meets most of the requirements for a large area detector in cosmic ray work.

See abstr. A704 of 1971. The recent findings of the Sydney air shower group concerning the existence of high-transverse-momentum events in air shower cores are disputed. It is shown that the multiple cores which are interpreted as large-transverse-momentum events are likely to be simulated by the detection fluctuations quoted by the Sydney group itself.