Depolarization of synchrotron radiation of a relativistic electron beam

TL;DR

This paper theoretically investigates how high-energy electron beams become polarized or depolarized when propagating in strong magnetic fields, revealing a rapid polarization increase at low parameters and significant radiation depolarization at high parameters.

Contribution

It provides a detailed analysis of the dependence of electron and radiation polarization on the parameter , highlighting the conditions for polarization saturation and depolarization effects.

Findings

Electron polarization increases rapidly for   1 and saturates near -0.8.

Depolarization of synchrotron radiation occurs, especially when initial spins are aligned parallel to the magnetic field.

Rate of self-polarization decreases significantly when   1.

Abstract

We present a theoretical study on the radiative self-polarization of a high-energy electron beam propagating perpendicular to a strong magnetic field. Recently, a similar setup has been proposed as a source of polarized electron and photon beams. We focus on the dependence of electron and radiation polarization on the dimensionless parameter $\varepsilon$, which is proportional to the product of electron energy and magnetic field strength. The numerical solution of the balance equation shows that the resulting electron beam polarization increases rapidly as a function of $\varepsilon$ for $\varepsilon \ll 1$ and saturates at a value of approximately $-0.8$. If $\varepsilon \gg 1$, the rate of self-polarization decreases significantly. At the same time, a substantial or nearly complete depolarization of synchrotron radiation is observed, particularly for an electron beam with spins initially aligned parallel to the field.