Distribution of clustering characteristics for STE-5. The histogram for on-orbit data is compared with (i) randomly simulated triggers (null hypothesis) and (ii) an end-to-end Monte Carlo (MC) simulation based on the full spacecraft mass model of GECAM-B, with isotropic primary protons and α particles. The MC result reproduces the observed mean-angular-distance distribution, indicating that the measured clustering is compatible with cascade footprints in the spacecraft structures.