The CERN target and horn concept for a neutrino factory based on muon beams

A conceptual design is presented for a high-power pion production target and collection system, which is suggested to be used as source for the proposed CERN muon-neutrino factory. A relatively low-energy proton beam of 2.2 GeV which is pulsed at 50 Hz with ∼1014 ppp and 4 MW average power has been chosen as driver. The deleterious effects of the up to 1 kW/g power densities deposited in the target and its surroundings by the proton beam are a major technical challenge since it seriously limits the lifetime of all solid components. A target, which consists of a free surface mercury-jet with a high axial velocity, allows efficiently to carry the heat away from the production region without need for beam windows. The secondary pions are collected and injected into the pion decay channel by means of a magnetic horn. This horn which has to surround the Hg-jet target is known to be very radiation resistant as well as light and easy to exchange. The suggested mechanical layout and technical parameters of the target, horn and cooling system are discussed. The critical issues are identified and a description of the R&D program designed to provide experimental proof of principle as well as providing engineering parameters is given.