Full Inverse Compton Scattering: Total Transfer of Energy and Momentum from Electrons to Photons

TL;DR

This paper introduces Full Inverse Compton Scattering (FICS), a regime where electrons transfer all their kinetic energy to photons, revealing new insights into energy transfer and potential experimental applications.

Contribution

The paper defines and analyzes the FICS regime, demonstrating total energy transfer from electrons to photons and exploring its implications for high-energy physics and thermodynamics.

Findings

FICS achieves 100% energy transfer from electrons to photons.

Relativistic electrons with large Lorentz factors can fully transfer energy at specific photon energies.

FICS can be used to probe the Unruh temperature and photon baths.

Abstract

In this article we discuss a peculiar regime of Compton Scattering that assures the maximum transfer of energy and momentum from free electrons propagating in vacuum to the scattered photons. We name this regime Full Inverse Compton Scattering (FICS) because it is characterized by the maximum and full energy loss of the electrons in collision with photons: up to 100 % of the electron kinetic energy is indeed transferred to the photon. In the case of relativistic electrons, characterized by a large Lorentz factor (gamma >> 1), FICS regime corresponds to an incident photon energy equal to mec^2/2 . We interpret such an astonishing result as FICS being the time reversal of direct Compton Scattering of very energetic photons (of energy much greater than mec2) onto atomic electrons. Although the cross section of Compton scattering is decreasing with the energy of the incident photon, making the process less probable with respect to other reactions (pair production, nuclear reactions, etc) when high energetic photons are bombarding a target, the kinematics straightforwardly implies that the back-scattered photons would have an energy reaching asymptotically me^2c^2 . FICS is instead the unique suitable working point in Compton scattering for achieving the total transfer of (kinetic) energy exactly from the electron to the photon. Experiencing transitions from the initial momentum to zero in the laboratory system, in FICS the electron is also subject to very large negative acceleration; this fact can lead to possible experiments of sensing the Unruh temperature and related photon bath. On the other side of the energy dynamic range, low relativistic electrons can be completely stopped by moderate energy photons (tens of keV), leading to full exchange of temperature between electron clouds and photon baths.