Radiation processes accompanying the axially channeled positrons. Problem of stimulation of resonant transitions between different quantum states

Abstract

An analytical expression is received for the effective interaction potential of a fast charged particle with the ionic crystal CsCl near the direction of axis ⟨100⟩ as a function of the temperature of the medium. By numerical analysis it is shown that the effective potential of axial channeling of positrons along the axis ⟨100⟩ of negatively charged Cl⁻ ions practically doesn't depend on temperature of the media. The wavefunction and the energy spectrum of the localized state are investigated, and the possibility is proved for the formation of metastable, two-dimensional relativistic positron systems or the positron atoms (PA), i.e. the bound state of a positron in the present case with a negatively charged axis of ions. The problem of one-photon decay of PA is investigated. The possibilities of stimulation of resonant transitions between quantum states of PA by the external hypersound are investigated in detail.

Keywords:

• ionic crystal
• positron
• channeling
• quantum state
• resonant transition
• electron–positron decay

Acknowledgements

This work was partially supported by ISTC Grant No. A-1602. AG thanks Professors A. Saharian and L.Sh. Grigoryan for useful discussions.