Electron capture from one- and two-electron atoms by fast positrons in dense plasmas

Electron capture processes by positrons from one- and two-electron atoms in dense plasmas are investigated in accordance with the classical Bohr–Lindhard model using the modified hyperbolic-orbit trajectory method. The interaction potential in dense plasmas has been approximated by the Debye–Hückel model. The modified hyperbolic-orbit trajectory for the positron path is obtained by the combination of the hyperbolic-orbit and straight-line trajectories with the modified impact parameter. The maximum value of the electron capture probability per electron for two-electron (He-like) atoms is smaller than that for one-electron (H-like) atoms. The maximum position of the electron capture probability is slightly shifted to the target nucleus with an increase of the target charge. The plasma-screening effect on the electron capture probability for He-like atoms is more effective than that for H-like atoms. However, the capture probabilities obtained by the straight-line trajectory for H-like and He-like atoms are identical.