Abstract
Spatial distribution of the first-layer neighbors in a random assemblage of equal spheres is discussed from the radial distribution function in the Percus-Yevick approximation The first-layer neighbors are defined as the particles which lie within the first peak of the radial distribution function. The average distance of the first layer from a central sphere is obtained along with a simple, approximate expression. In the range higher than the particle volume fraction 0.4, the particle distribution can be modeled such that the average number of the first-layer neighbors is twelve, one half of them being distributed inside of the position expressed by Eq. (3) and the other half lying outside.
