Electron scattering in isotonic chains as a probe of the proton shell structure of unstable nuclei

TL;DR

This paper predicts how elastic electron scattering can reveal proton shell structures in unstable nuclei across different isotonic chains, aiding future experimental investigations.

Contribution

It introduces a theoretical framework combining covariant mean-field models and Helm fits to connect scattering observables with proton shell configurations.

Findings

Charge form factors vary with proton shell filling.

Scattering observables are sensitive to proton shell structure.

Proposed method can inform about single-particle level occupation.

Abstract

Electron scattering on unstable nuclei is planned in future facilities of the GSI and RIKEN upgrades. Motivated by this fact, we study theoretical predictions for elastic electron scattering in the N=82, N=50, and N=14 isotonic chains from very proton-deficient to very proton-rich isotones. We compute the scattering observables by performing Dirac partial-wave calculations. The charge density of the nucleus is obtained with a covariant nuclear mean-field model that accounts for the low-energy electromagnetic structure of the nucleon. For the discussion of the dependence of scattering observables at low-momentum transfer on the gross properties of the charge density, we fit Helm model distributions to the self-consistent mean-field densities. We find that the changes shown by the electric charge form factor along each isotonic chain are strongly correlated with the underlying proton shell structure of the isotones. We conclude that elastic electron scattering experiments in isotones can provide valuable information about the filling order and occupation of the single-particle levels of protons.