The SCRIT Electron Scattering Facility at RIKEN: The World's First Electron Femtoscope for Short-Lived Unstable Nuclei

Electron scattering at high energy (>100 MeV) has been playing as an electron femtoscope (a femtometrescale electron microscope), which provides reliable information on the internal structure of nuclei [1]. This is because electron scattering has several features that make it an ideal probe of nuclear structure: (1) The Coulomb interaction is well understood and model independent, (2) Electrons are structureless particles, and (3) Electrons can deeply probe the internal structure of nuclei without causing any serious disturbance. By using these features, elastic and inelastic electron scattering has been applied to the study of stable nuclei, from deuteron to uranium. Elastic electron scattering is a key tool to determine the charge density distribution of nuclei, whereas inelastic electron scattering provides various information about their nuclear structure, such as their excited states, giant resonances, and nucleon properties through the single-proton knock-out reaction and other reactions [1].