The Structure of Extensive Air Showers Near the Axes

Abstract

The lateral distribution of electrons and also of the mean energy of extensive air showers (EAS) were observed with a detector array composed of 14 scintillation detectors, 15 \v{C}erenkov detectors, an arrival direction detector and a neon hodoscope. In particular the precise structure near the axes could be detected by the neon hodoscope. Each EAS was specified by various parameters, that is, the lateral distributions of electrons and energy flow, μ-mesons, and nuclear active component, and it was found that the structure of the EAS thus observed are different from case to case.
Near the axis the lateral distributions of electrons are rather flat and varied gradually from r^−0.4 to r^−1.0 according to the distance from the axis, up to a few meters. The slope of the distribution between 5 m–50 m distance from the shower axis is well fitted by the predicted one from the Nishimura-Kamata theory, adjusting the value of the s-parameter. The observed lateral distribution of mean energy of electrons is expressed by E=7.5×10⁸×r^−0.7±0.1 ev in the region from the axis to 7 m.
The probable influences on the structure near the region the axis are discussed.