The analyzing powers of ϩ and Ϫ were measured using an incident 22-GeV/c transversely polarized proton beam at the Brookhaven Alternating Gradient Synchrotron. A magnetic spectrometer measured Ϯ inclusive asymmetries on a hydrogen and a carbon target. An elastic polarimeter with a CH 2 target measured pp elastic-scattering asymmetries to determine the beam polarization using published data for the pp elastic analyzing power. Using the beam polarization determined from the elastic polarimeter and asymmetries from the inclusive spectrometer, analyzing powers A N for Ϯ were determined in the x F and p T ranges (0.45-0.8) and (0.3-1.2 GeV/c), respectively. The analyzing power results are similar in both sign and character to other measurements at 200 and 11.7 GeV/c, confirming the expectation that high-energy pion inclusive analyzing powers remain large and relatively energy independent. This suggests that pion inclusive polarimetry may be a suitable method for measuring future beam polarizations at BNL RHIC or DESY HERA. Analyzing powers of ϩ and Ϫ produced on hydrogen and carbon targets are the same. Various models to explain inclusive analyzing powers are also discussed.
The 0 inclusive and semi-inclusive, single-spin asymmetries have been measured using transversely polarized, 200-GeV/c proton and antiproton beams colliding with an unpolarized hydrogen target. The measured asymmetries are consistent with zero within the experimental uncertainties for the kinematic region Ϫ0.15Ͻx F Ͻϩ0.15 and 1Ͻp T Ͻ4.5 GeV/c. Improvements in the data analysis showed that our earlier large asymmetries at p T Ͼ3 GeV/c were not correct. These data indicate that PQCD expectations seem confirmed and the higher-twist contribution to the single-spin asymmetry in 0 production at x F ϭ0 is not large. Additional evidence for such a conclusion comes from the measurement of a semi-inclusive 0 asymmetry, where associated charged particles are detected opposite to the 0 azimuthal direction. This experiment also provides high-statistics data on the inclusive 0 cross sections for pp and pp collisions at ͱsϷ19.4 GeV.
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