Layout and tests of silicon pad detectors for the PHOBOS experiment at RHIC

The PHOBOS experiment at RHIC, which is currently under construction, is designed to measure the particle multiplicity and to reconstruct low-momentum tracks in heavy ion Au–Au collisions. Both tasks are accomplished with silicon pad detectors. The silicon pad detectors are single-side devices with up to 1540 pads per detector. A special double-metal readout scheme for pad detectors provides a cost-effective method to connect detectors with different pad geometries to identical standard VLSI electronics. Different pad geometries have been designed and tested to optimise the pulse height and position measurement. Results of tests on the signal response and detector parameters for different pad configurations are be presented.