The collision of ultrashort high-density $e^{-}$ or $e^{-}$ and $e^{+}$ beams at 10s of GeV, to be available at the FACET II and in laser wakefield accelerator experiments, can produce highly collimated $\mathrm{<ruby><rb>\gamma </rb><rt>がんま</rt></ruby>}$ rays (few GeVs) with peak brilliance of $10^{27}\mathrm{ph}/\mathrm{s}{\mathrm{mm}}^2{\mathrm{mrad}}^{2}0.1\%\mathrm{BW}$ and up to $10^5$ nonlinear Breit-Wheeler pairs. We provide analytical estimates of the photon source properties and of the yield of secondary pairs, finding excellent agreement with full-scale 3D self-consistent particle-in-cell simulations that include quantum electrodynamics effects. Our results show that beam-beam collisions can be exploited as secondary sources of $\mathrm{<ruby><rb>\gamma </rb><rt>がんま</rt></ruby>}$ rays and provide an alternative to beam-laser setups to probe quantum electrodynamics effects at the Schwinger limit.

• Received 13 April 2018

DOI:https://doi.org/10.1103/PhysRevAccelBeams.22.023402

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Published by the American Physical Society