Single-photon annihilation of channeled positron in crystals
National Research Tomsk Polytechnic University, Tomsk, Russia
2 Tomsk State Pedagogical University, Tomsk, Russia
Accepted: 10 January 2023
Published online: 13 March 2023
A free electron–positron pair can only annihilate into two or more photons, while in an external electromagnetic field, it is possible a single-photon annihilation. In the present work, for the first time, the differential cross section of single-photon annihilation of a channeled positron with a K-shell electron of one of the crystal atoms is derived within the framework of QED theory. It is shown that this cross section has a complicated dependence on the positron entry angle with respect to the crystal plane, and the obtained orientation dependence is different for the different positron transverse energy levels. The dependence of the differential cross section on the positron longitudinal energy is studied. The obtained dependence is similar to the dependence for single-photon annihilation of a positron with an electron of an individual atom, calculated in the first Born approximation.
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