Ionization Cooling of Muon Beams

Paul Lebrun, Fermilab

Intense neutrino sources based on high energy muon beams are currently under study. The front-end of this new accelerator complex requires a cooling section section, where the transverse emittance of the low momentum (200 MeV/c) muon beam gets reduced by a factor ~4.  Due to the short lifetime of the muons, and the large incoming emittance, ionization cooling appears to be the only feasible option.  A muon cooling channel is therefore based on the use of liquid hydrogen absorbers and short linacs embedded in solenoidal lattice.

Computer simulations play an essential role at the design stage. This project requires a multi-disciplinary approach: we borrowed heavily from High Energy Physics codes, and constructed two separate codes: ICOOL and DPGeant.  The latter is the old Geant3 code, upgraded to double precision.  Similar effort based on the PATH code is being pursued at CERN.  At Fermilab, we are currently using the new Geant4, a relatively new C++ package for particle physics simulation.  After a brief introduction of muon ionization cooling,two distinct designs will be presented and the essence of these computer codes along with the"learned lessons" will be discussed. 

(pdf)