Magnet system for helical muon cooling channels

Abstract

A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides superimposed solenoidal, helical dipole, and helical quadrupole fields has shown considerable promise in providing six-dimensional cooling of muon beams. The analysis of this muon cooling technique with both analytic and simulation studies has shown significant reduction of muon phase space emittance. A particular channel that has been simulated is divided into four segments each with progressively smaller apertures and stronger fields to reduce the equilibrium emittance so that more cooling can occur. The fields in the helical channel are sufficiently large that the conductor for segments 1 and 2 can be Nb3Sn and the conductor for segments 3 and 4 may need to be high temperature superconductor. This paper will describe the magnetic specifications for the channel and two conceptual designs on how to implement the magnetic channel.