Note on polarization of p-bar beams

A polarized hydrogen target and PL=0.5 GeV/c to capitalize on the S(1936) effect is considered. The latest measurements, suggest a maximum Δδ/δ of order 1% for pp collisions in this region - assuming that the S(1936) reflects underlying resonance structure in a specific spin state. Higher momentum regime for the filter, PL ∼ 1.5 to 3.1 GeV/c is proposed in an attempt to take advantage of more peripherial reactions: namely, p-barp → Δ-barp + p-barΔ, p-barp → Δ-barΔ. The threshold for the second reaction is around 2.3 GeV/c, above which it is expected to dominate. Not only should absorption be increased by these reactions, but also p-barp scattering through the two-stage reaction pp-bar → (Δ-barp, p-barΔ, Δ-barΔ) → p-barp