An effective method for polarising antiprotons

We propose an effective method for polarising antiprotons in a storage ring by means of a parallel moving polarised electron beam. If their relative kinetic energy is adjusted to the order of 1 keV the probability for spin exchange is as large as 〈σPzz〉 ≈ 270 barn. Using a 80% polarised electron beam with a peak current of 1.2 A and an average of 32 mA a polarisation of the antiproton beam of 50% in 1.5 hours is achieved under realistic conditions in a 1.8 T m storage ring. The basis of this proposal are new calculations of the spin transfer cross sections and a state of the art source of polarised electrons. The examples of a specialised low energy polariser ring and the polarisation in a high energy experimental storage ring show that the method is realisable with a polarised electron source based on todays technology. PACS. 29.27.Hj Polarised beams – 13.88.+e Polarisation in interactions and scattering – 29.25.Bx Electron sources – 29.20.Dh Storage rings