Executive Summary

We propose to perform a proof-of-principle demonstration of a target system based on a free mercury jet, including magnetic focusing/capture of secondary pions/muons, suitable for use in a 4-MW, 50-GeV proton beam as part of a neutrino “superbeam ” and/or neutrino factory facility. Such a target system would also be provide higher intensity muon beams for the PRISM project. The proposed studies emphasize the survival of a prototype target system against issues of single proton pulses: dispersal of the jet target by mechanical “shock ” and/or vaporization due energy deposition by the proton beam, and possible damping of these effects by the strong magnetic field of the capture solenoid. A first phase of such studies has been carried out at BNL and CERN, in which the interaction of a mercury jet with a proton beam, and with a 20-T solenoid magnet, have been investigated separately, with encouraging results. Long-term issues of radiation damage and materials fatigue are to be addressed in separate studies. • The studies proposed here are to be made using small numbers ( ≈ 1,000 total) of intense proton pulses from the 50-GeV ring at J-PARC. (Preliminary studies coul