Strained Layer Crystalline Undulator

TL;DR

This paper proposes a novel crystalline undulator using a silicon-germanium mixed crystal with specific bending parameters, enabling high-energy radiation emission with improved stability and technical feasibility.

Contribution

It introduces a new design for a crystalline undulator employing a silicon-germanium crystal with variable germanium content, achieving the required bending parameters and stability.

Findings

The mixed crystal can achieve the necessary bending amplitude and period.

Predicted stability against misfit dislocations.

Potential for high-energy electromagnetic radiation emission.

Abstract

Ultrarelativistic charged particles are predicted to emit hard electromagnetic radiation of undulator type while being channeled in a crystal with periodically bent crystallographic planes. The recently proposed crystalline undulator with the bending amplitude smaller than the distance between the bent planes and the bending period shorter than the period of channeling oscillations is far superior to what was proposed previously. In the same time, it is more challenging from the technical point of view because its bending period has to be in the sub-micron range. It is shown that a mixed crystal of silicon-germanium with properly varying germanium fraction can have the necessary bending parameters. Moreover, it is predicted to be stable against misfit dislocations.