Small-scale readout system prototype for the STAR PIXEL detector

A prototype readout system for the STAR PIXEL detector in the Heavy Flavor Tracker vertex detector upgrade is presented. The PIXEL detector is a Monolithic Active Pixel Sensors (MAPS) based silicon pixel vertex detector fabricated in a commercial CMOS process that integrates the detector and front-end electronics layers in one silicon die. Two generations of MAPS prototypes designed specifically for the PIXEL are discussed. The readout architecture for the PIXEL has been recently prototyped in a telescope system consisting of three small MAPS sensors arranged into three parallel and coaxial planes. This proposed readout architecture is simple and scales to the size required to readout the final detector. The real-time hit finding algorithm necessary for data rate reduction in the 135 mega pixel detector is described, and aspects of the PIXEL system integration into the existing STAR framework are addressed. The complete system has been recently tested and shown to be fully functional.