A mini linac based positron source

Abstract We have installed in Saclay a demonstration setup for an intense positron source in November 2008. It is based on a compact 6 MeV electron linac to produce positrons via pair production on a tungsten target. A relatively high current of 0.15 mA compensates the low energy, which is below the neutron activation threshold. The expected production rate is 4x10 11 fast positrons per second. A set of coils is arranged to select the fast positrons from the diffracted electron beam in order to study the possibility to use a rare gas cryogenic moderator away from the main flux of particles. A first part of the commissioning of the linac has been performed. First attempts at measuring the fast positron flux are underway. This setup is part of a project to demonstrate the feasibility of an experiment to produce the H + ion for a free fall measurement of neutral antihydrogen (H). Its small size and cost could be of interest for a university laboratory or industry for materials science applications. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)