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arXiv · 2608.04932

A plasma photocathode for spin-polarized electron beams via state-selected hydrogen halide photofragments

Lars Reichwein·Thomas C. Wilson·Dimitris Sofikitis·Chinmaya Singh·T. Peter Rakitzis·Bernhard Hidding·Alexander Pukhov·Liangliang Ji·Markus Büscher
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Abstract

Spin-polarized electron beams are essential tools for probing fundamental symmetries and for the search beyond the Standard Model. While plasma-based accelerators are a promising pathway towards higher-energy frontiers, they have so far failed to deliver a competitive polarized source: existing proposals are challenging to realize and achievable polarizations remain far below conventional sources. Here, we introduce a photocathode-like scheme, applied to a gas of pre-polarized hydrogen and halogen atoms. A VUV and a visible laser pulse excite the halogen atoms to create a two-component ionization medium, consisting of low-threshold excited halogen atoms and high-threshold polarized hydrogen. Particle-in-cell simulations show witness beams with tens of pC charge retaining up to 97% of the initial polarization, rivaling state-of-the-art conventional sources.

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Lars Reichwein, Thomas C. Wilson, Dimitris Sofikitis, Chinmaya Singh, T. Peter Rakitzis, Bernhard Hidding, Alexander Pukhov, Liangliang Ji, Markus Büscher. 2026-08-05. A plasma photocathode for spin-polarized electron beams via state-selected hydrogen halide photofragments. https://arxiv.org/abs/2608.04932

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