Nuclear “diffuseness” probed by proton-nucleus diffraction

In this contribution, we propose a way to probe nuclear density profile, especially, nuclear surface diffuseness. We discuss the relationship between the nuclear surface diffuseness and the elastic scattering differential cross section at the first diffraction peak of high-energy nucleon-nucleus scattering as an efficient tool for extracting the nuclear surface information from limited experimental data involving short-lived unstable nuclei. The high-energy reaction is described by a reliable reaction theory, the Glauber model. Extending the idea of the black sphere diffraction model, we find that the nuclear radius and surface diffuseness are reflected in the proton-nucleus elastic scattering diffraction at the first peak position, that is, one can extract both the nuclear radius and diffuseness simultaneously, using the position of the first diffraction peak and its magnitude of the elastic scattering differential cross section. The reliability of this approach is confirmed by using realistic density distributions obtained by a microscopic mean-field model. The possibility of separating neutron and proton surfaces is also discussed.