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CMS Detector


The CMS pixel detector detects charged particles as they emerge from the collision and measures their positions. One important use is the reconstruction of the decay vertex of bottom quarks, which is an important way to identify them. With more than 60 million channels, the pixel detector is a complex device that relies on sophisticated electronics and software. Our group developed calibration and data acquisition software and commissioned and debugged the detector.

Group: Anders Ryd, Josh Thompson, Ben Kreis.


The collision rate at the LHC is a billion times higher than data recording technology can accommodate, so a rapid decision must be made about which to record. The trigger, which does this job, distinguishes interesting collisions from those that are more mundane, keeping only one in a billion for future analysis. We must ensure that the trigger is doing precisely what we want it to do. Our Trigger group provides trigger monitoring software to both experts and shift crews, has developed tools to monitor the acceptance/rejection ratio and timing of the various trigger paths, and provided a backup electron trigger for the start-up phase. We also have provided tools such as an interim Level 1 trigger emulator and detector to physics converter.

Group: Peter Wittich, Lorenzo Agostino, Werner Sun, Don Teo, Darren Puigh, Avishek Chatterjee, Ritchie Patterson.

Detector Operations

CMS has millions of channels of detectors readout by fast electronics, the vast majority of which must be working properly in order to collect useful data. Moreover, operations must be carefully coordinated with the LHC, so that CMS can adjust to changing conditions, and to coordinate maintenance and repairs.

Group: Anders Ryd

Detector upgrades for high luminosity

The SLHC upgrade to the LHC, which would increase its luminosity by a factor of ten to 1034/cm2/s, will require changes to some of the CMS detectors and electronics. We are developing new sensor technologies and are exploring strategies for fast triggering on tracks at detector level.

Thinned sensors - Julia Thom, Scott Johnson (Undergraduate).
Track Trigger Simulation - Anders Ryd, Emanuelle Salvati (postdoc).
Track-Trigger Hardware - Julia Thom, Jim Alexander, Scott Johnson (Undergrad). Meeting time: Tuesdays at 1 pm.