Angular distribution of positrons in coherent pair production in deformed crystals

TL;DR

This paper derives a formula for the angular distribution of positrons produced by high-energy photons in deformed crystals, with numerical results for SiO2 and diamond under acoustic wave deformation.

Contribution

It introduces a general formula for the differential cross-section of pair production in deformed crystals, considering arbitrary deformation fields and specific cases like small incident angles.

Findings

Numerical calculations show the angular distribution depends on crystal type and deformation.

Deformation fields, such as acoustic waves, significantly influence positron emission patterns.

Results are provided for SiO2 and diamond crystals under specific deformation conditions.

Abstract

We investigate the angular distribution of positrons in the coherent process electronpositron pair creation process by high-energy photons in a periodically deformed single crystal with a complex base. The formula for the corresponding differential cross-section is derived for an arbitrary deformation field. The case is considered in detail when the photon enters into the crystal at small angles with respect to a crystallographic axis. The results of the numerical calculations are presented for${\mathrm{SiO}}_{2}$ and diamond single crystals and Moliere parameterization of the screened atomic potentials in the case of the deformation field generated by the acoustic wave of S-type.