Positron extraction to an electromagnetic field free region

We describe a scheme for high efficiency (about 90%) extraction of 50 ns positron bunches from a buffer gas trap in an electromagnetic field free region. The positrons are time bunched to approximately 1 ns (FWHM) and focussed to less than 1 mm ({\sigma}). The target is kept at ground potential which is an advantage for many applications. The results compare well with SIMION simulations.