High-energy polarized electron beams from the ionization of isolated spin polarized hydrogen atoms

We propose a laser-based method for the preparation of high-energy, highly-polarized electrons, from the ionization of isolated spin-polarized hydrogen (SPH) atoms. The SPH atoms are prepared from the photodissociation of HBr, using two consecutive shaped UV pulses of ps duration. By appropriately timing and focusing the pulses, we can spatially separate the highly polarized SPH from other unwanted photoproducts, which then act as the target for the ion-acceleration lasers. The density of SPH can surpass $\approx$10$^{18}$ cm$^{-3}$, allowing the production of GeV electrons with polarization larger than 90%.