Comparison of photon colliders based on e-e- and e+e- beams

TL;DR

This paper compares photon collider options based on e-e- and e+e- beams, concluding e-e- beams are superior due to lower background noise and fewer interfering reactions, making them essential for optimal gamma-gamma collision experiments.

Contribution

The study provides a detailed comparison demonstrating that e-e- beam-based photon colliders are significantly more effective than e+e- based ones, highlighting their advantages in background suppression.

Findings

e-e- beams produce lower background gamma-gamma to hadrons

e+e- beams have higher background noise complicating gamma-gamma measurements

e-e- beams are essential for cleaner gamma-gamma collider experiments

Abstract

At photon colliders gamma-gamma, gamma-electron high energy photons are produced by Compton scattering of laser light off the high energy electrons (or positrons) at a linear collider. At first sight, photon colliders based on e-e- or e+e- primary beams have similar properties and therefore for convenience one can use e+e- beams both for e+e- and gamma-gamma modes of operation. Below we compare these options and show that e-e- beams are much better (mandatory) because in the e+e- case low energy background gamma-gamma to hadrons is much higher and e+e- annihilation reactions present a very serious background for gamma-gamma processes.