Screening effects on electron captures by positrons

Abstract

Screening effects on the electron capture in collisions of high energy positrons with one- and two-electron atoms are investigated in accordance with the modified Bohr–Lindhard capture model using the classical curved trajectory method. The modified hyperbolic-orbit trajectory method is applied to describe the motion of the positron projectile in order to obtain the scaled electron capture probability as a function of the impact parameter and the effective target charge. The result shows that the maximum value of the electron capture probability per electron for He atom is smaller than that for H atom. It is found that the position of the maximum electron capture probability is shifted to smaller impact parameter with an increase of the target charge. However, the capture probabilities using the straight-line trajectory for H and He atoms are identical.