First Demonstration of Ionization Cooling by the Muon Ionization Cooling Experiment
Muon colliders have the potential to carry the search for new phenomena to energies well beyond the reach of the LHC in the same or smaller footprint. Muon beams may be created through the decay of pions produced in the interaction of a proton beam with a target. To produce a high-brightness beam from such a source requires that the beam be cooled. Ionization cooling is the novel technique by which it is proposed to cool the beam. The Muon Ionization Cooling Experiment collaboration has constructed a section of an ionization cooling cell and used it to provide the first demonstration of ionization cooling. Here the observation of ionization cooling is described. The cooling performance is studied for a variety of beam and magnetic field configurations. The cooling performance is related to the performance of a possible future muon collider facility.
Transverse Emittance Change in MICE 'Solenoid Mode' with Muon Ionization Cooling
Emittance reduction of muon beams is an important requirement in the design of a next-generation Neutrino Factory or Muon Collider. Ionization cooling has been proposed to meet this requirement, whereby beam emittance is reduced by passing a beam through absorbing material. Tight focussing is required in both horizontal planes, which is achieved in many designs using solenoid focussing. Ionization cooling has been demonstrated in the Muon Ionization Cooling Experiment (MICE) in 'flip' mode, where the solenoid field flips polarity across the absorber. We present the performance of MICE in 'solenoid' mode, where the field polarity does not change across the absorber.
Muon Ionization Cooling Demonstration by Normalized Transverse Emittance Reduction in MICE 'Flip Mode'
Low emittance muon beams are central to the development of facilities such as a Neutrino Factory or a Muon Collider. The international Muon Ionization Cooling Experiment (MICE) was designed to demonstrate and study the cooling of muon beams. Several million individual muon tracks have been recorded passing through a liquid hydrogen or a lithium hydride absorber. Beam sampling routines were employed to account for imperfections in beam matching at the entrance into the cooling channel and enable an improvement of the cooling performance. A study of the change in normalized transverse emittance in a flipped polarity magnetic field configuration is presented and the characteristics of the cooling effect are discussed.
Emittance Exchange in MICE
Highly brilliant muon beams for a muon collider can be made from the bombardment of protons against a target producing pions, which subsequently decay into muons. Such a muon beam occupies a large phase-space volume and must be cooled to achieve luminosities suitable for a muon collider. The Muon Ionization Cooling Experiment (MICE) has demonstrated transverse ionization cooling. A muon collider requires both longitudinal and transverse cooling. This can be achieved through a wedge-shaped absorber, where both the longitudinal and transverse phase spaces are simultaneously manipulated during the ionization cooling process. The change in longitudinal and transverse phase space densities obtained from placing a polyethylene wedge into the MICE cooling channel are presented here.