A HIGH POWER RADIATION COOLED TARGET FOR A NEUTRINO FACTORY

A solid target is being considered for the production of pions by intense high-energy proton beams for a neutrino factory. The target would consist of a rotating ring or a string of discrete bars travelling in a circle. The target would rotate in vacuum and the power would be radiated to the water-cooled walls of the vacuum chamber. Steady powers of up to 100 MW can be dissipated by thermal radiation at temperatures of ~2500 K, using a suitable refractory material such as tantalum or tungsten. Under thermal cycling and pulsed beam conditions, the thermal stresses and shock induced in the toroid are being studied. This is expected to significantly reduce the power capabilities and shorten the life by fatigue. The present design of the facility requires an average power dissipation in the target of up to 1 MW; this appears feasible at present. It is proposed to levitate, guide and rotate the target by electromagnetic forces generated by suitable arrangements of coils. A target wheel variation is also being considered for practical reasons.