Kiriakos "Kerry" (Northside College Prep, Chicago)
Mentor: Marco Verzocchi
TThe six week project focused on a portion of the CMS detector, the silicon-based pixel detector and its tracking system, detailing its hardware, circuitry, and accompanying software. The CMS (Compact Muon Solenoid) is a one of two major detectors operating on the Large Hadron Collider in Geneva, Switzerland. Used to study known particles and their interactions, as well as to look for new particles and interactions, the CMS is an experiment that reconstructs the paths and momenta of the ejecta of proton-proton collisions. Operating at 8 TeV, 40 million collisions happen every second, with bunch crossings taking place every 25 nanoseconds. Following the fanning of the ejecta from the interactions point, the particles emitted first encounter a series of silicon based pixel detectors known as FPIX and BPIX (Front & Barrel pixel detectors). The purpose of these detectors is to provide high resolution 3D space points required for track pattern recognition and reconstruction.
If ionizing radiation makes its way through a pixel, a minute charge may be created. The sensor then relays this charge to a read-out chip and its circuitry to send to the Data Acquisition System if it is determined that it is an "interesting" collision. What I explored was how exactly the analog voltage created by a piece of ionizing radiation is turned into a digital signal while exploring the numerous calibration tests designed to eliminate noise and fine tune the system. I learned how the system in which the pixel detector encodes its digital data exactly functions and how this data is transferred from the experiment to a read-out location. I also learned about the fabrication process of such silicon sensors and read-out chips and performed and learned about various probing exercises that are done to ensure their functionality.