”Optical” spin rotation phenomenon and spin-filtering of antiproton beams in a nuclear pseudomagnetic field

Abstract

Despite long-lasting study and seeming simplicity, the investigation of two-and three-particle interactions is still a topical problem. Because these investigations are very important, the experiments with antiproton, proton and deuteron interactions are included in scientific programs of modern accelerators COSY, GSI and LHC. In studding of these interactions, polarization observables sensible to different mechanisms of interaction are of particular interest as well as the differential reaction cross-section. Modern storage rings with a long lifetime of a beam permit one to carry out qualitatively new experiments with polarized beams and targets. Particularly, in the spin-filtering experiments [1] of antiprotons (protons, deuterons), it is possible to measure a spin-dependent part of a forward scattering amplitude [1]-[3]. Moreover, it is possible to measure the real part of a coherent elastic amplitude of proton (antiproton, deuteron) scattering at zero angle when the plane formed by the target polarization vector and the beam momentum direction lies in the orbit pane of the beam and the angle between these two vectors differs from 0, π or π/2 [2]. Measurement of the spin-dependent part of a forward scattering amplitude is possible