Compton ionization momentum spectrum from neutral hydrogenlike atoms

Abstract

We investigate the ionization momentum spectrum of a bound system composed of two oppositely charged particles, which interact via electromagnetic forces, under nonrelativistic Compton scattering. Our analysis focuses on positronium, a unique system that can be experimentally realized. We find that as the incident photon energy increases, the ionization momentum spectrum of positrons and electrons converges to their respective bound-state momentum distributions. This property distinguishes positronium from the hydrogen atom and can be attributed to the mass ratio ${R}_{m}$ of the two particles in the system. We provide a detailed analysis of the effect of ${R}_{m}$ and demonstrate the existence of hydrogenlike atoms with ${R}_{m}\ensuremath{\ne}1$ that exhibit similar behavior in Compton scattering. Such atoms correspond to exotic systems found in nature.