Positron-Driven Sources of Low Emittance Muons for Future Colliders

Muon colliders are an intriguing option for future lepton colliders with the ability to reach high energy with high luminosity, conceivably even into the >10 TeV scale. Muons benefit from the increased particle mass with respect to electrons allowing for acceleration with recirculating beams. However, Muon colliders face significant challenges with the production of high flux low emittance beams and managing the short lifetime of muons. The leading approach for generating muon and anti-muon pairs relies on a high intensity proton beam to produce vast quantities of relatively low energy muons which are then captured, accelerated and “cooled” to lower the muon beam emittance. An alternative approache is using high energy positron beams on fixed targets to produce high energy muons with lower emittance. A positron beam of >45 GeV is required for efficient muon pair production on a fixed target. The muons that are produced have an energy of >20 GeV and a lifetime of >450 microseconds in the laboratory frame increasing the possibility for beam capture and beam collection. We will present a review of the proposed concepts for positron-driven low emittance muon sources for future colliders, possible schemes for implementation and needed areas for research and development.