First performance results of the Phobos silicon detectors

The Phobos experiment concluded its first year of operation at RHIC taking data in Au-Au nucleus collisions at roots(nn) = 65 GeV and 130 GeV/nucleon pair. First preliminary results of the performances of our silicon detector s in the experiment are summarized. The Phobos experiment uses silicon pad detectors for both tracking and multiplicity measurements. The silicon sens ors vary strongly in their pad geometry. In this paper, we compare the sign al response, the signal uniformity and signal-to-noise performance as measu red in the experiment for the different geometries. Additionally, we invest igate effects of very high channel occupancy on the signal response. (C) 20 01 Elsevier Science B.V. All rights reserved.