Accelerator requirements for next generation neutron sources

The most powerful accelerator-driven neutron sources for condensed matter research use proton beam spallation in pulsed mode of operation. The facilities built by now or being constructed provide substantial advantages compared to existing fission reactor sources, which are related to the increased efficiency of using the neutrons available due to the pulsed nature of the beam. On the other hand, the time average flux of these sources remains below that of fission reactors, and this assures continuing superiority for the most powerful reactors in some applications. The challenge for the next generation of accelerator-based neutron sources is to enhance the time average neutron flux well above that of the most powerful reactor sources. This can be achieved with high-power linear accelerators operating at peak H+ beam currents above 100 mA in ms long pulses and at about 3 GeV proton beam energy or somewhat higher. The total proton beam power will be in the range of 10 MW or more, while the beam quality can be relaxed compared to accelerators designed for H− beams and injection capability.