Polarization effects in the nuclear excitation by positron–electron annihilation

In this paper polarization effects in the nuclear excitation by positron–electron annihilation (NEPEA) process are considered. We calculated cross-sections for the NEPEA with wave functions of bound electron and incoming positron in point nuclear Coulomb field. The results are compared to predictions which are derived using Born approximation. Results for the annihilation on the K-electron are presented. We found that cross-section for magnetic transition is much more pronounced for orientation of electron spin in positron direction. For electric transition cross-sections with parallel spin orientation are larger than for antiparallel, at least for small positron energy.