Detection significance of proto-clusters as a function of aperture radius (top) and as a function of completeness limit (bottom) for three different redshift intervals. Top: The solid curves show the mean significance, while the dashed curves show the maxima. A redshift interval of Δ_{z (50%)} was used. Bottom: The completeness limit, Δz (X%), covers the range 30–90%. The solid lines show the results for an aperture radius of 0.5 r_pc and dashed lines for 1 r_pc.