Analyzing power of inclusive production of. pi. sup + ,. pi. sup minus , and K sub S sup 0 by polarized protons at 13. 3 and 18. 5 GeV/ c

We have measured the analyzing power in {pi}{sup +}, {pi}{sup {minus}}, and {ital K}{sub {ital S}}{sup 0} production by a polarized proton beam at 13.3 and 18.5 GeV/{ital c}. The data cover the central and the beam fragmentation region, in the transverse-momentum range up to 2 GeV/{ital c}. The results indicate that sizable effects are present at high {ital x}{sub {ital F}} and also persist into the hard-scattering region for {ital K}{sub {ital S}}{sup 0} and {pi}{sup +}. A zero value of the analyzing power was observed for {pi}{sup {minus}} production.