A testing set-up for a micro-analysis positron beam facility

A description is given of an electrostatically guided positron beam set-up designed for testing the performance of a remoderation stage in a positron micro-beam facility. In this set-up positrons from a 15 mCi 22Na source are moderated in a 3.5 μm thick tungsten foil and focused onto the entrance of a 90° cylindrical mirror deflector. At the exit of the deflector the positrons are focused onto a micro-channel plate with phosphor screen assembly in order to characterise the beam diameter and intensity at the entrance of the remoderation stage.