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Neutrino Factory

Neutrino factory

Neutrino Sources based on Muon storage rings have found a lot of interest in the High Energy Physics community. The strong point is the capability of providing very intense, very well collimated neutrino beams. In such facility, an intense proton beam hits a target, pions decay into muons in long decay channels, the muons have to be cooled and then accelerated and finally get injected into a storage ring where they decay. A recent Neutrino Factory interest is to explore whether FFAGs could be used to provide a more economical Neutrino Factory than one which uses cooling.

MICE

International Muon Ionization Cooling Experiment Future neutrino factories or muon colliders will require that intense muon beams are accelerated and stored. Many tricks are required to do this efficiently. The muons originate from the decay of pions and the beam has a very high initial emittance (rms size times rms divergence). The emittance must be reduced substantially to match the acceptance of downstream accelerators. The muon lifetime is finite and conventional cooling methods cannot be used: ionisation cooling is the only possibility. In an ionisation cooling channel the muons are focussed by solenoidal magnetic fields onto a series of low Z 'absorbers' where ionisation loss reduces both transverse and longitudinal momentum; RF cavities subsequently restore the longitudinal momentum thereby reducing the net emittance of the beam. MICE is a UK/US/Japan/European collaboration to build a section of muon cooling channel and demonstrate ionisation cooling. MICE will consist of one lattice cell of the US Neutrino Factory Feasibility Study 2 cooling channel design and will make single-particle measurements of emittance reduction with a precision of one part in a thousand. The experiment will take place at the Rutherford Appleton Laboratory in a new muon beam from the 800 MeV ISIS proton accelerator. The John Adams Institute, in collaboration with RAL, will provide the Absorber Focus Coil (AFC) modules for MICE.

These modules contain pairs of high-field superconducting coils surrounding liquid hydrogen absorbers. The group is also working on the design of thin windows for the absorbers and RF cavities, the beam optics of the cooling channel, emittance measurements, and calculations of energy loss and multiple scattering in liquid hydrogen (ELMS).