2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/16512Random-matrix theory is used to study the mesoscopic fluctuations of the excitation gap in a metal grain or quantum dot induced by the proximity to a superconductor. We propose that the probability distribution of the gap is a universal function in rescaled units. Our analytical prediction for the gap distribution agrees well with exact diagonalization of a model Hamiltonian.Mesoscale and Nanoscale Physicstext