Suppression of High-pT Neutral Pion Production in Central Pb+Pb Collisions at sqrt(sNN) = 17.3 GeV Relative to p + C and p + Pb Collisions

Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at {radical}S{sub NN} = 17.4 GeV at midrapidity (2.3 {approx}< {eta}{sub lab} {approx}< 3.0) over the range 0.7 {approx}< p{sub 1} {approx}< 3.5 GeV/c. The spectra are compared to {pi}{sup 0} spectra measured in Pb+Pb collisions at {radical}S{sub NN} = 17.3 GeV in the same experiment. For a wide range of Pb+Pb centralities (N{sub part} {approx}< 300), the yield of {pi}{sup 0}'s with {rho}{sub {Lambda}} {approx}> 2 GeV/c is larger than or consistent with the p+C or p+Pb yields scaled with the number of nucleon-nucleon collisions (N{sub coll}), while for central Pb+Pb collisions with N{sub part} {approx}> 350, the {pi}{sup 0} yield is suppressed.