The following materials have been identified as being of particular interest for targets and beam windows:
The ultimate ambition is to be able to predict operating lifetimes for as many of the above materials as possible in terms of integrated proton fluence for the high energy proton accelerator parameter space (e.g. temperature, dose rate, duty factor, dynamic stress) while accepting that such predictions are inherently challenging and may not be expected to be applied to safety critical items.
For some of these materials, (graphite, structural steels), there is a long history of use in nuclear fission applications and a large body of research on irradiation effects due (mostly) to low-energy neutrons. For others (beryllium, tungsten) there is a more limited and recent body of work directed at fast neutron environments (e.g. fusion reactors; CCFE have just equipped their JET reactor with a tungsten / beryllium wall system). The immediate tasks are to assess existing knowledge and how it might be applied to these new irradiation environments and to determine what new research will be most effective.
During the first stage of the proposed program (see Program Plan), a subset of the above listed materials will be identified as ripe for new experimental research while others will be recognized as benefiting from the application of research previously conducted, currently underway, or already planned as part of the on-going fission and fusion radiation damage R&D efforts. Guidance provided by the high power target community will need to prioritize the experimental research as the current program may only provide enough resources to address one, or possibly two, of these, very dissimilar materials (depending on synergies with existing research). Materials not addressed by the initial program could be addressed in future or parallel collaborative activity.