Development of the CMS pixel detector

A readout chip for the CMS pixel detector has been developed in the radiation hard DMILL process. The chips ability to operate under LHC conditions was tested in a high-rate pion beam with track densities up to 3×107 cm−2 s−1. The observed degradation of the detection efficiency with increasing particle flux is compared with the data-loss mechanisms inherent to the readout architecture. First detector modules with 16 chips on a low-mass high-density interconnect are evaluated. The next iteration of the readout chip is designed for a 0.25 μm process with a radiation-tolerant layout.