Planar wiggler as a tool for generating hard twisted photons

TL;DR

This paper derives formulas for the probability of radiation of twisted photons by particles in a planar wiggler, showing that quantum recoil does not affect certain angular momentum selection rules, with applications to high-energy electron radiation.

Contribution

It provides explicit formulas for twisted photon radiation probability in planar wigglers, including quantum recoil effects, and confirms the robustness of the angular momentum selection rule.

Findings

Quantum recoil does not spoil the angular momentum selection rule.

Explicit formulas for twisted photon radiation probability are derived.

Radiation of twisted photons by GeV electrons in wigglers and crystalline undulators is analyzed.

Abstract

Simple formulas for the probability of radiation of twisted photons by scalar and Dirac particles with quantum recoil taken into account are derived. We show that the quantum recoil does not spoil the selection rule for the forward radiation of twisted photons in the planar undulator: $m+n$ is an even number, where $n$ is the harmonic number and $m$ is the projection of the total angular momentum of the radiated twisted photon. The explicit formulas for the radiation probability of twisted photons produced in the planar wiggler are obtained with account for the quantum recoil. The radiation of twisted photons by GeV electrons in the planar wiggler and in the crystalline undulator is investigated.