Single-Spin Asymmetry in Inclusive $pi^0$ Production Measured at the Protvino 70 GeV Accelerator

Single Spin Asymmetries (SSA) $A_N$ measured in the two reactions at the Protvino 70 GeV accelerator are presented. $A_N$ in the reaction $p+p(pol)->pi^0+X$ in the central region is close to zero within the error bars. SSA in the reaction $pi^- +p(pol)->pi^0+X$ in the polarized target fragmentation region is equal to $(-15 pm 4)%$ at $|x_F|>0.4$. There is an indication that the asymmetry arises at the same pion energy in the center of mass system.