The design and performance of the FNAL high-energy polarized beam facility

This paper describes a polarized-proton and antiproton beam with 185-GeV/c momentum in the Fermilab MP beam line which is currently operational. The design uses the parity-nonconserving decay of lambda and antilambda hyperons to produce polarized protons and antiprotons, respectively. A beam-transport system minimized depolarization effects and uses a set of 12 dipole magnets that rotate the beam-particle spin direction. A beam-tagging system determines the momentum and polarization of individual beam particles, allowing a selection of particles in definite intervals at momentum and polarization. The authors measured polarization of the beam by using two types of polarimeters which verified the determination of polarization by a beam-particle tagging system. Two of these processes are the inverse-Primakoff effect and the Coulomb-nuclear interference (CNI) in elastic proton-proton scattering. Another experiment measured the π0 production asymmetry of large-xF values; this process may now be used as an on-line beam polarimeter. Since polarized beams and polarized proton targets became available for use in high-energy experiments, various measurements of the polarized phenomena have been made. The physics objectives for the Fermilab polarized beam facility up to 185 GeV/c are in part based on the fact that there are already several experimental indications that spin effects are significant at high energy. They are: measurements of π0 production at high p perpendicular (p perpendicular > 2.0 GeV/c) in proton collisions at CERN and in π- proton collision at Serpukhov revealed sizable asymmetries at 24 GeV/c and 40 GeV/c, respectively. Hyperons produced at large xF inclusively off nuclei and hydrogen at CERN. Fermilab, and ISR were observed to have high polarizations