High power neutron converter for low energy proton/deuteron beams

In the framework of the European program to define a second generation Radioactive Ion Beam (RIB) facility, the Legnaro National Laboratories (LNL) are proposing the construction in the next years of a specialized national facility for RIB originated by fission fragments produced by fast neutrons (SPES). Protons/deuterons of 40 MeV (150 kW) will produce in a converter about 1014 neutrons per second centered at around 14 MeV that will induce fission in a suitable fissile target, with the aim of 1013 fission per second at least. A rotating wheel equipped with light conversion material cooled mainly by thermal radiation has been chosen as converter. The material of the highly activated converter has been selected to withstand the power of the beam without constraints concerning the diffusion of radioactive atoms. Different converter materials, i.e. 12C and 13C graphites, glass carbon and boron carbide, have been selected and thermal tests performed with a high power electron beam. The design of the converter prototype for 20 MeV (50 kW) proton/deuteron and the results of the material selection are presented here.