Design of the T2K target for a 0.75-MW proton beam

The T2K experiment began operation in April 2009 [1]. It utilises what is projected to become the world's highest pulsed power proton beam at 0.75 MW to generate an intense neutrino beam. T2K uses the conventional technique of interacting a 30 GeV proton beam with a graphite target and using a magnetic horn system to collect pions of one charge and focus them into a decay volume where the neutrino beam is produced. The target is a two interaction length (900 mm long) graphite target supported directly within the bore of the first magnetic horn which generates the required field with a pulsed current of 320 kA. This paper describes the design and development of the target required to meet the demanding requirements of the T2K facility. Challenges include radiation damage, stress waves, design and optimisation of the helium coolant flow, and integration with the pulsed magnetic horn. Conceptual and detailed engineering studies were required to develop a target system that could satisfy these requirements.