Demodulation of a positron beam in a bent crystal channel

TL;DR

This paper investigates how a modulated positron beam evolves in a crystal channel, introducing the demodulation length as a key measure, and demonstrates the potential for using crystalline undulators as coherent X-ray and gamma-ray sources.

Contribution

It introduces the demodulation length parameter and shows that certain crystal channels can preserve beam modulation for practical X-ray and gamma-ray laser applications.

Findings

Existence of crystal channels with large demodulation length

Potential use of crystalline undulators as coherent X-ray sources

Demodulation length as a measure of beam modulation preservation

Abstract

The evolution of a modulated positron beam in a planar crystal channel is investigated within the diffusion approach. A detailed description of the formalism is given. A new parameter, the demodulation length, is introduced, representing the quantitative measure of the depth at which the channelling beam preserves its modulation in the crystal. It is demonstrated that there exist crystal channels with the demodulation length sufficiently large for using the crystalline undulator as a coherent source of hard X rays. This finding is a crucial milestone in developing a new type of lasers radiating in the hard X ray and gamma ray range.