Regular Article

Small recoil momenta double ionization of He and two-electron ions by high energy photons

¹ Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel
² A. F. Ioffe Physical-Technical Institute, St. Petersburg 194021, Russia
³ National Research Center “Kurchatov Institute” B. P. Konstantinov Petersburg Nuclear Physics Institute Gatchina, St. Petersburg 188300, Russia

^* Corresponding author: liverts@phys.huji.ac.il

Received: 18 April 2020
Received in final form: 13 June 2020
Published online: 25 August 2020

Abstract

We calculate various differential and double differential characteristics of ionization by a single photon for H⁻, He and for the two-electron ions with Z = 3, 4, 5 in the region of the so-called quasi-free mechanism (QFM) domination. We employ highly accurate wave functions at the electron-electron coalescence line where coordinates of both ionized electrons coincide. We trace the Z dependence of the double differential distributions. For all considered targets we discuss the dependence of the photoelectron energy distribution on the photon energy. Our calculation demonstrated the rapid decrease of QFM contribution with increase of the difference in energy of two outgoing electrons, and with decrease of the angle between two outgoing momenta. As a general feature, we observe the decrease of QFM contribution with nuclear charge growth.