Plans for Electron Beam Stress Testing of Target Materials suitable for a Neutrino factory

The suggestion of a radiation cooled target for a neutrino factory was made shortly after the first NuFact workshop as a means of dissipating large amounts of average power and sustaining large temperature rises [1]. The suggestion was made as an alternative to the proposed water cooled rotating band and liquid metal jet targets which were believed to have significant practical difficulties. In the present case, the target, in the form of a toroid with the beam entering on a tangent is made to rotate and can be several metres in circumference providing a large volume with which to absorb the deposited beam power. At 2 GeV approximately 25% of the 4 MW beam power is deposited in the target volume (nominally 2 cm diameter and 20 cm long), which, depending on the repetition rate of the proton beam (in the limits of 15-100 Hz) leads to temperature increases per pulse of between 400 and 1000 degrees C. The target is allowed to maintain a high temperature in order to benefit from the T radiation cooling law. Clearly, the higher the repetition rate of the beam, the lower the temperature rise experienced by the target, and the higher is the scope to increase the beam power. Fresh target material is presented to the beam at each pulse by virtue of the rotation and each piece of the target sees approximately 1% of the average beam power (~100kW).