The production of a low emittance muon beam is interesting for muon collider projects. In such context we study the production of positive and negative muon beams at 22 GeV, from $e^{+}$ beam-vs-fixed target collisions, with a very small transverse and longitudinal emittance of $25\pi \mathrm{nm}\mathrm{rad}$ and $3\times 1\pi \mathrm{mm}\mathrm{GeV}$, respectively. In order to cope with the small conversion efficiency of positrons into muon pairs and the divergence of the beams, we connect thin targets by a quadrupole-only transport line common to three beams (${\mu }^{+}$, ${\mu }^{-}$, and $e^{+}$) at two different energies ($\mu$ at 22 GeV and $e^{+}$ at 44 GeV), where the line is specially designed to match the muon beam phase space over $\pm 5\%$ energy spread and to mitigate the effect of multiple scattering with the targets on all beams. The transport line allows us to use a larger fraction of target material, increasing the muon population by a factor of 10 per positron bunch and splitting the power deposition over 20 to 40 targets, while keeping the muon beam emittance equal or similar to one from a single thin target of 1% of a radiation length. It might be possible to integrate this line into an accumulator ring in order to increase the muon bunch population over hundreds of positron bunches.

• Received 18 June 2020
• Accepted 31 August 2020

DOI:https://doi.org/10.1103/PhysRevAccelBeams.23.091601

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Published by the American Physical Society