PoS - International Workshop on Low Energy Electron Positron Physics at Jefferson Lab

The long-time interest for positron beams at Jefferson Lab (JLab) forms the basis for an upgrade initiative known as Ce+BAF 12 GeV. It will feature high duty factor beams with intensities up to 1 μA within an RF-structure. The positrons for these beams will be produced in the bremsstrahlung shower generated by a lower energy mA electron beam impinging on a high-Z target, utilizing the PEPPo (Polarized Electrons for Polarized Positrons) technique for producing highly spin-polarized positrons in a compact accelerator footprint. This methodology opens up the possibility of also producing lower energy positron beams with high intensity and spin polarization. Beams generated from this source would enable unique experimental programs at JLab with the perspective to reveal details of the electromagnetic interaction, unravel the structure of nucleons and nuclei, and investigate the existence of physics beyond the standard model.

The success of Ce+BAF 12 GeV relies on the development of crucial R&D for generating the required electron and positron beams. Consequently, new capabilities should emerge in the meantime, with opportunities for low-energy (sub-GeV) Nuclear Physics, Atomic Physics and Materials Science. Notably, this R&D aims at intense beams both for generation of polarized electrons at mA intensity and linac based positron beams that have the potential to exceed present capabilities by orders of magnitude. Altogether, output of this effort has a great potential to facilitate a venue for low energy e+/e- physics.

The LEEPP@JLab International Workshop explored new pathways for Science with both unpolarized/polarized electron and positron beams. Beam energies ranging from 1-100 MeV for both species as well as moderated/slow positrons to several eV have been investigated. The subjects addressed during the workshop comprise:

- Positron sources, related equipment and diagnostics;

- Nuclear Physics;

- Atomic Physics;

- Materials Science;

- Tests of the Standard Model Physics.

Scientific Editorial Board:

Axel Schmidt, George Washington University

David Cassidy, University College London

Douglas Higinbotham, Jefferson Lab

Eric Voutier, IJCLab / Université Paris-Saclay

Farida Selim, Arizona State University

Joe Grames, Jefferson Lab

Kevin Jordan, Jefferson Lab

Tyler Kutz, Johannes Gutenberg University Mainz