Generating ultra-dense pair beams using 400 GeV/c protons

TL;DR

This paper proposes a novel experimental scheme using 400 GeV/c protons to generate ultra-dense, low-divergence electron-positron beams capable of studying collisionless instabilities relevant to astrophysics.

Contribution

It introduces a new method for producing ultra-dense pair beams with controllable composition, enabling exploration of astrophysical plasma phenomena in laboratory settings.

Findings

Simulations show generation of $10^{13}-10^{14}$ pairs at high densities.

Beams are quasi-neutral and larger than several skin-depths.

Potential to study magnetic field growth and radiation signatures.

Abstract

A previously unexplored experimental scheme is presented for generating low-divergence, ultra-dense, relativistic, electron-positron beams using 400 GeV/c protons available at facilities such as HiRadMat and AWAKE at CERN. Preliminary Monte-Carlo and Particle-in-cell simulations demonstrate the possibility of generating beams containing $10^{13}-10^{14}$ electron-positron pairs at sufficiently high densities to drive collisionless beam-plasma instabilities, which are expected to play an important role in magnetic field generation and the related radiation signatures of relativistic astrophysical phenomena. The pair beams are quasi-neutral, with size exceeding several skin-depths in all dimensions, allowing for the first time the examination of the effect of competition between transverse and longitudinal instability modes on the growth of magnetic fields. Furthermore, the presented scheme allows for the possibility of controlling the relative density of hadrons to electron-positron pairs in the beam, making it possible to explore the parameter spaces for different astrophysical environments.