Angular Distributions of Secondary Particles Produced in High-Energy Nuclear Collisions and the Two-Center Model of Multiple Meson Production

Abstract

The angular distributions of shower particles from 54 nuclear interactions of protons and neutrons with energies g ${10}^{12}$ ev in a stack of nuclear emulsions are analyzed. The method consists essentially in normalizing the angular distributions of all events in the $x=logtan\ensuremath{\theta}$ scale to the same dispersion $\ensuremath{\sigma}$. One finds a very significant deviation from the normal distribution predicted by hydrodynamical models. The deviation goes in the direction indicated by the two-center model (two maxima in the plot over the $x$ coordinate). The correlation between the separation of the two emitting centers and $\ensuremath{\sigma}$ is also in qualitative agreement with the model. The angular distribution in the rest system of the emitting centers is found to be roughly isotropic. The two-center model also offers an explanation for certain characteristic features observed for the angular distribution of events with a small number of shower particles (${n}_{s}\ensuremath{\leqq}5$). On the basis of this model a coefficient of inelasticity of \ensuremath{\approx}0.2 is obtained for these events.Interactions characterized by small evaporation (${N}_{h}\ensuremath{\leqq}5$) and small numbers of shower particles (${n}_{s}\ensuremath{\leqq}20$) show the characteristic two-maximum shape. The same shape is found for presumably central collisions with heavy nuclei in the emulsion (${N}_{h}g8, {n}_{s}g40$). However, the group of collisions with ${N}_{h}\ensuremath{\leqq}5$, ${n}_{s}g20$ does not show the two maxima. The last two observations cannot be explained by the present simple form of the two-center model.The results of this paper are in good agreement with a similar analysis carried out by Gierula, Mi\ifmmode \mbox{\k{e}}\else \k{e}\fi{}sowicz, and Zielinski.