Inclusive negative particle pT spectra in p-nucleus and nucleus-nucleus collisions at 200-GeV per nucleon

The HELIOS experiment has measured inclusivep ⊥ spectra of negative particles in the rapidity region 1.0<y<1.9. The general shape of thep ⊥ spectra in p +W, O+W and S+W is similar, but cannot be described by a single exponential. Compared to p+p collisions, an excess is observed for low and highp ⊥. This effect increases with the projectile mass. Except for very lowE ⊥, the average transverse momentum <p ⊥> is found to be approximately constant up to the highest accessible values of E ⊥.