Radiative Double Electron Capture Observed During O[sup 8+]+C Collisions At 38 Mev

Abstract

Radiative double electron capture (RDEC) is a one‐step process during which two free (or quasifree) target electrons are captured into bound states of the projectile, e.g., into an empty K‐shell, and the energy excess is released as a single photon. This process can be considered as a time inverse of double photoionization. As photon interacts with one electron only, RDEC is due to electron‐electron interaction. Moreover, RDEC is investigated during bare ion‐atom collisions and, unlike double photoionization, it does not have background from spectator electrons. Thus, RDEC may be the simplest, clean tool for exploration of the electron‐electron interaction in the presence of electromagnetic fields generated during ion‐atom collisions. Recently, an experiment dedicated to the RDEC process with 38 MeV O8+ ions colliding with a carbon foil was conducted at Western Michigan University using the tandem Van de Graaff accelerator. This experiment confirmed that the observation of such process is possible and allowed for estimation of the RDEC cross section of 3.2(1.9) b, which is significantly greater than the theoretically predicted value of 0.15 b.