Magic Numbers as Response-Closure Peaks in the ECSM Framework: A Regime-Aware Robustness Test Using AME2020 Nuclear Shell-Gap Data

This paper tests whether standard nuclear magic numbers appear as finite-response closure peaks in AME2020 binding-energy data. Using two-neutron and two-proton separation-energy discontinuities, the analysis finds robust magic-minus-non-magic shell-gap lifts across cleaning choices and mass regimes. After excluding the lightest nuclei, positive neutron and proton closure signals remain and most of the standard magic-number sequence is recovered by direct shell-gap ranking.