Plastic scintillator centrality detector for BRAHMS

An array of 40 tiles of thin plastic scintillators is used to construct the outer layer of the charged particle multiplicity detector for the BRAHMS experiment at the Relativistic Heavy Ion Collider (RHIC). Each tile is a square with 12 cm long sides and 5 mm thickness. The light from each of the scintillators is collected by wavelength shifting fibers embedded on the periphery. The light collection is uniform within 5% over the tile with the edge effect limited to 4 mat along the edge. The response is found to be linear in the high-multiplicity environment at RHIC with An + An beams at roots(NN) of 200 GeV. (C) 2003 Elsevier B.V. All rights reserved.