Pseudorapidity Distributions of Charged Particles in d + Au and p + p Collisions at $\sqrt{s_{_{NN}}}$ = 200GeV

Abstract

The measured pseudorapidity distributions of primary charged particles are presented for d + Au and p + p collisions at ${\sqrt{s_{_{NN}}} =}$ 200 GeV over a wide pseudorapidity range of ${\rm \mid \eta \mid \le}$ 5.4. The results for d + Au collisions are presented for minimum-bias events and as a function of collision centrality. The measurements for p + p collisions are shown for minimum-bias events. The ratio of the charged particle multiplicity in d + Au and p + A collisions relative to that for inelastic p + p collisions is found to depend only on ${}$, and it is remarkably independent of collision energy and system mass. The deuteron and gold fragmentation regions in d + Au collisions are in good agreement with proton nucleus data at lower energies.Comment: 4 pages, 3 figures. To appear in the proceedings of Seventeenth International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004), Oakland, California from January 11-17, 2004. Submitted to Journal of Physics G: Nuclear and Particle Physic