Toward polarized antiprotons: Machine development for spin-filtering experiments

The paper describes the commissioning of the experimental equipment and the machine studies required for the first spin-filtering experiment with protons at a beam kinetic energy of 49.3 MeV in COSY. The implementation of a low-β insertion made it possible to achieve beam lifetimes of τ_b=8000 s in the presence of a dense polarized hydrogen storage-cell target of areal density d_t=(5.5 ±0.2 )×1 0¹³ atoms /cm² . The developed techniques can be directly applied to antiproton machines and allow the determination of the spin-dependent p ¯p cross sections via spin filtering.