Electron-scattering experiments resolve short-range correlations among nucleons

According to the shell model, the protons and neutrons - collectively known as nucleons - that make up nuclei move independently in discrete quantum orbits and are bound by an average potential created by their mutual attractive interactions. But that picture is too naive. In the 1980s, electron-scattering experiments that knocked protons from both valence and deeply bound nuclear orbitals found only 60-70% of the number predicted by the mean-field approximation. © 2008 American Institute of Physics.