The CMS Pixel Detector

Silicon detectors are widely used in particle physics due to their high efficiency, fast readout and low dead time, and their manufacturability by the microelectronics industry. Over the past decades these detectors have evolved into low granularity sensors, with applications in many areas of physics and engineering. In high energy physics, pixel detectors were developed to be sensitive to X-rays and charged particles, and to have high spatial resolution and low capacitance, which make them able to operate during longer periods in a high radiation environment.

The silicon pixel detector is the heart of the CMS detector. It aims to provide high-precision position measurements to reconstruct charged particle trajectories, producing information for the high level trigger and for the reconstruction of tracks. It consists of a three layers barrel with two disks, one on each end. It was installed in July 2008 in the innermost region of CMS.

The CMS pixel detector was conceived over 10 years ago. Although the detector was designed and built using the best technology available at that time, radiation exposure will degrade its performance and a replacement of the inner regions of the detector will be required by 2017.

The upgrade plan for the CMS pixel detector foresees the replacement of the current system with an ultra-light pixel detector, with four-barrel layers and three end-cap disks. The inner layer will be even closer to the interaction point at r = 3.0 cm.

The SPRACE engineers plan for the upgrade is to get involved in the system integration and tests of the pixel detector, allowing members of the center to get acquainted with the pixel hardware and to get integrated with groups from Fermilab and CERN that are leading the project.

Among the expertise that is expected to be acquired are those related to system integration, readout system, and expertise in radiation-hard systems.