Low-Energy Positron Beams: Positron Sources, Moderation and Beam Setups

Abstract:

Low-energy positron beams are essential tools for a large variety of experiments in solid state and surface physics, materials science, and fundamental research. In university scale laborato ries, positron beams β⁺ emitters are used as positron source, whereas at large-scale facilities such as electron linacs or research reactors positrons are created by pair production. In this contribution, we first focus on β⁺ sources and nuclear reactors for positron production. Then the process of positron moderation for the brightness enhancement of beams is described using phase space considerations. The properties of moderator materials and different geometries of experimental setups for positron (re-)moderation are also discussed. Among numerous positron beam setups, which are employed around the world either on a lab scale or at large scale facilities, four layouts will be presented as examples: a positron micro-beam, a pulsed beam, a trap-based beam, and a spin-polarized positron beam. Fi nally, we discuss prospects for producing a high-intensity polarized positron beam via absorption of a γ-beam which in turn was generated by inverse Compton scattering.

• Periodical: Solid State Phenomena (Volume 373)
• Pages: 49-63
• DOI: https://doi.org/10.4028/p-sm6FT4
• Online since: July 2025
• Authors: Christoph Hugenschmidt*
• Keywords: Beta Sources, Moderation, Pair Production, Positron Beams, Research Reactors

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