Development of a novel silicon stripixel detector for RHIC-PHENIX detector upgrade

A new single-sided silicon strip detector has been developed for the silicon vertex tracker of the PHENIX detector at the Relativistic Heavy Ion Collider in Brookhaven National Laboratory (BNL). The novel "stripixel" detector concept developed by the BNL Instrumentation Division was applied to the first prototype silicon sensor. The novel feature of the stripixel concept is two-dimensional (2-D) position sensitivity with single-sided processing achieved by charge sharing between two interleaved electrodes in one pixel. Signals are read out projectively by double layers of aluminum strips. The first prototype stripixel sensors with the size of 34.3 × 64.6 mm and thickness of 250 and 400 μm were fabricated. The detector with readout electronics was constructed to evaluate the prototype sensor performance by using an analog multiplexer chip with charge sensitive preamplifier-shaper circuits (VA2 chip of IDEAS). The sensor performance on charge sharing, detection efficiency, signal-to-noise ratio, and position resolution has been tested with a radioactive source and a GeV particle beam at KEK-PS. The stripixel detector concept, the specification of the first prototype stripixel sensor, and the test results are presented.