Parametric (quasi-Cherenkov) cooperative radiation produced by electron bunches in natural or photonic crystals

TL;DR

This study uses numerical modeling to analyze parametric (quasi-Cherenkov) cooperative radiation from electron bunches in natural or photonic crystals, revealing distinct pulse structures and noise effects under different diffraction conditions.

Contribution

It provides new insights into the pulse structure and noise influence on parametric radiation in natural and artificial crystals during dynamical diffraction.

Findings

Two strong pulses are emitted at small and large angles in both Laue and Bragg diffraction.

Small-angle radiation saturates at fewer particles than large-angle radiation under Bragg conditions.

In Laue diffraction, each pulse has two peaks linked to the bunch's front and back ends.

Abstract

We use numerical modeling to study the features of parametric (quasi-Cherenkov) cooperative radiation arising when an electron bunch passes through a crystal (natural or artificial) under the conditions of dynamical diffraction of electromagnetic waves in the presence of shot noise. It is shown that in both Laue and Bragg diffraction cases, parametric radiation consists of two strong pulses: one emitted at small angles with respect to the particle velocity direction and the other emitted at large angles to it. Under Bragg diffraction conditions, the intensity of parametric radiation emitted at small angles to the particle velocity direction reaches saturation at sufficiently smaller number of particles than the intensity of parametric radiation emitted at large angles. Under Laue diffraction conditions, every pulse contains two strong peaks, which are associated with the emission of electromagnetic waves at the front and back ends of the bunch. The presence of noise causes a chaotic signal in the interval between the two peaks.