A mega watt electron positron conversion target

Intense sources of positrons are required to achieve in high energy electron-positron colliders the desired elevated luminosities. Positrons are produced by diverting part of the high energy electrons onto a target, from which low energy positrons are collected and re-injected into the e--e+ collider. Within the frame of a design study for a high luminosity beauty factory, ARES [1] presently under consideration at FRASCATI, a conceptual design has been worked out for the targeting of a 2 GeV- electron beam with an average current of 770 μA and an average power of 1.5 MW. In order to handle these extreme power densities, a rotating wheel is considered intercepting the beam at its periphery such that the beam power is spread around its circumference. The target concept has already been described earlier. In this paper the authors summarize the principle features, consider certain critical technical aspects and discusses in some detail the prevailing radiation problems