A HIGH INTENSE REACTOR BASED POSITRON SOURCE

An intense source of monoenergetic, low energy positrons is presented The positrons are produced by pair production from high energy gamma-r ays after the capture of thermal neutrons in cadmium. The pair product ion itself takes place in a stack of layers, each consisting of two co ncentric rings made of tungsten foils. The source is placed in a beam tube at the Research Reactor Munich at Garching. From first experiment al data, we can extrapolate an intensity of 2 x 10(8) slow positrons p er second and a spot size of less than 26 mm.