Evidence for electron capture to the continuum by protons scattered at non-0° angles from Ar atoms

Abstract

The process of electron capture to the continuum (ECC) has been studied at non-0\ifmmode^\circ\else\textdegree\fi{} electron emission angles in a type of experiment in which the electrons ejected in a given direction are detected in coincidence with the outgoing projectiles scattered on the target nucleus in the same direction. Triply differential cross sections (differential with respect to the energy and angle of the ejected electron and the angle of the scattered projectile) have been determined for 75-keV proton on Ar collisions at scattering angles 3.7\ifmmode^\circ\else\textdegree\fi{}, 5.0\ifmmode^\circ\else\textdegree\fi{}, and 8.1\ifmmode^\circ\else\textdegree\fi{}. The occurrence of the cusp peak in the coincidence spectra gives an evidence for the existence of the ECC process at non-0\ifmmode^\circ\else\textdegree\fi{} emission angles. The experimental data are compared with results of first-order distorted-wave Born and classical trajectory Monte Carlo (CTMC) calculations.