Pseudorapidity distributions of charged particles in d + Au and p + p collisions at

The measured pseudorapidity distributions of primary charged particles are presented for d+Au and p+p collisions at over a wide pseudorapidity range of |η|≤ 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 Npart, 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.