A ring lattice for a 2-TeV muon collider

A 2 TeV on 2 TeV muon collider has been proposed with a design luminosity of 10³⁵ cm^-2 s^-1. The ring has a circumference of about 8 km, and the muon lifetime at 2 TeV corresponds to approximately 1000 turns before the beam luminosity degrades substantially. The cooling process produces a round beam with a normalized emittance of 50×10^-5 mrad and 2×10¹² muons per bunch. The beam´s large emittance requires that β* at the interaction point (IP) must be only 3×10^-3 m, in order to reach the design luminosity. Due to the hourglass effect, a very short bunch length equal to β* must be maintained to reach the design luminosity. To prevent the bunch from spreading in time, the momentum compaction factor α must be 10^-5, or less; that is, the ring must be nearly isochronous. The small value of β* leads to very large peak beta values in the final-focus quadrupoles, and unprecedented chromaticities. Correction of the large chromaticities makes for a highly nonlinear interaction region (IR). This IR, combined with the isochronicity condition, makes design of a muon collider lattice very challenging. The lattice presented here builds on a base ring design described in a feasibility report, and, more recently, in several muon-collider workshop proceedings