Systematic Investigations of the He-4 Monopole

Abstract

Nuclear form factors are fundamental properties of nuclei and connected to several quantities of a nucleus at the same time. Precise data on form factors can be used to stringently test theoretical calculations and predictions on nuclear structure, whereas in particular chiral perturbation theory has raised interest in the current decade among the research community. One quantity that drew attention in the theoretical field of Few-Body-Physics is the monopole transition form factor of He-4, calculated with chiral potentials and established phenomenological potentials. For a more precise determination of the monopole transition form factor data were taken at the A1 collaboration by using electron scattering on He-4 as experimental technique. Measuring the investigated kinematics from 0.5 fm-2 to 5.0 fm-2 also with effectively reduced density inside the target cell opened the possibility to create a full target model for background subtraction. The data was analysed by using Monte-Carlo techniques and different parametrisations of the monopole resonance and the background to test model dependencies. The more precise data presented in this work opens now the opportunity for theorists to track the origin of these deviations and gain a deeper insight into Few-Body-Physics.