A Compact Source of Positron Beams with Small Thermal Emittance

TL;DR

This paper proposes a compact, low-cost positron source using electrostatic traps that produces low-emittance beams suitable for accelerator physics, with potential applications in advanced acceleration techniques.

Contribution

It introduces a novel positron source design combining a Penning-Malmberg trap, electrostatic compressor, and RF accelerator, achieving low emittance at reduced size and cost.

Findings

Positron thermal emittance comparable to photocathode guns.

Modeling shows acceleration to 17.6 MeV with low emittance.

System offers a compact alternative for accelerator research.

Abstract

We investigate electrostatic traps as a novel source of positron beams for accelerator physics applications. Penning-Malmberg (PM) traps are commonly employed in low-energy antimatter experiments. Positrons contained in the trap are cooled to room temperature or below. We calculate the thermal emittance of the positrons in the trap and show that it is comparable to or better than the performance of state-of-the-art photocathode guns. We propose a compact positron source comprised of a PM trap, electrostatic compressor, and rf accelerator that can be built and operated at a fraction of the cost and size of traditional target-based positron sources, albeit at a reduced repetition rate. We model the acceleration of a positron bunch up to an energy of 17.6 MeV with a final thermal emittance of 0.60 $\mu$m-rad and bunch length of 190 $\mu$m. This system may be useful for acceleration physics studies, such as investigations of flat-beam sources for linear colliders and positron plasma wakefield acceleration.