University of Chicago

Our research group from the Enrico Fermi Institute has been part of the ATLAS experiment at the LHC since 1994.  The group has grown with time and now consists of five faculty members, together with research personnel, PhD students, and senior technical personnel.  About twenty people at Chicago are principally engaged in work on ATLAS.

We have been involved in the construction and commissioning of the ATLAS Tile Calorimeter. This detector system plays an essential role in measuring the energy and direction of quarks and gluons produced in the high energy collisions.  At Chicago we built part of the calorimeter's mechanical structure together with much of the front-end electronics for processing and measuring signals from the calorimeter.  We greatly benefited in the electronics work from the strong Electronics Development Group of the Enrico Fermi Institute.

The ATLAS calorimeter system can indirectly detect new particles which carry off substantial energy but pass through the thick calorimeter without creating a signal. Their presence is reflected by a very asymmetric distribution of energy for the particles directly observed. Nature demands a symmetric distribution of energy, which implies that something undetected must be running off with the rest of the energy. Such new weakly interacting particles have been proposed as the source of the dark matter of the universe and several members of our physics team are preparing analyses to search for them.

Recently, some members of our group have been developing plans to improve ATLAS's ability to select interactions containing particles which decay a small but finite distance from their point of creation. They would build special purpose electronics to process the fast signals in real time and provide this additional information to the computers used to select and record interactions of interest.

Chicago is fortunate to be one of the two hosts of the US ATLAS Midwest Tier 2 computing center.  This facility allows us fast access to the data through very high speed networks and substantial computing resources.

While our group is firmly based at the University of Chicago about one third of our members are in permanent residence at CERN to help with detector commissioning, operation, and initial data analysis.