An Experimental Investigation of the Nucleon Cascade in Water

The nucleon cascade in water produced by primaries of energy greater than 20×${10}^9$ ev has been examined using an array of Geiger-Müller counters and a 31-channel hodoscope. Over 15 000 showers have been studied. Transition curves for various primary energies, barometric coefficients for various multiplicities and at different depths, root mean square lateral spreads, and intensities at different depths are given. The experimental results are compared with the theory of the nucleon cascade developed by Messel and his co-workers. In particular, the variation of lateral spread with depth substantiates their conclusion that the differential cross section for nucleon-nucleon collision at high energies has a very peaked form in the forward direction.