A low-neutron background slow-positron source

The addition of a thermionic RF gun and a photocathode RF gun will allow the advanced photon source APS.linear accelerator linac.to become a free-electron laser FEL.driver. As the FEL project progresses, the existing high-charge DC thermionic gun will no longer be critical to APS operation and could be used to generate high-energy or low-energy electrons to drive a slow-positron source. We investigated possibilities to create a useful low-energy source that could operate semi-independently and would have a low-neutron background. q1999 Elsevier Science B.V. All rights reserved.