Experimental estimates of the photon background in a potential light-by-light scattering study

TL;DR

This study investigates background photon signals in high-power laser experiments to inform future light-by-light scattering detection, focusing on background sources and mitigation strategies using a single laser pulse in a vacuum.

Contribution

It provides experimental characterization of photon background sources in high-power laser setups, aiding the development of photon-photon scattering detection methods.

Findings

Surface scattering dominates at low residual gas pressures.

Background levels can be mitigated by improving optical surface quality.

Extrapolation suggests background can be reduced at higher intensities.

Abstract

High power short pulse lasers provide a promising route to study the strong field effects of the quantum vacuum, for example by direct photon-photon scattering in the all-optical regime. Theoretical predictions based on realistic laser parameters achievable today or in the near future predict scattering of a few photons with colliding Petawatt laser pulses, requiring single photon sensitive detection schemes and very good spatio-temporal filtering and background suppression. In this article, we present experimental investigations of this photon background by employing only a single high power laser pulse tightly focused in residual gas of a vacuum chamber. The focal region was imaged onto a single-photon sensitive, time gated camera. As no detectable quantum vacuum signature was expected in our case, the setup allowed for characterization and first mitigation of background contributions. For the setup employed, scattering off surfaces of imperfect optics dominated below residual gas pressures of $1\times 10^{-4}$ mbar. Extrapolation of the findings to intensities relevant for photon-photon scattering studies is discussed.