ANL ATLAS GROUP

The mission of the ASC is to support ATLAS physics analysis for ATLAS physicists at US mid-west Institutes. We are one of the three Analysis Support Centers in the US. We offer a model Tier-3 for ATLAS analysis, physics analysis expertise, software consultation meeting and office space for visitors, a dedicated video conference facility, computer clusters and user accounts. We are also organizing ATLAS analysis workshops and Tier3 meetings

Argonne has contributed centrally to all phases of the ATLAS Tile Calorimeter. Design, prototyping, and fabrication of modules and electronics were carried out in the US in close collaboration with the University of Chicago, University of Illinois. Michigan State University, and the University of Texas at Arlington. Bob Stanek from Argonne was the Project Leader for the Tile Calorimeter System from 2005 until 2009. The modules for Extended Barrel A (EBA), one of three barrel assemblies that comprise the Tile Calorimeter, were assembled and tested at Argonne. In the picture at left, EBA is shown in the ATLAS cavern at the moment of completion of its assembly from 64 separate modules in May 2006. This completed the mechanical installation of the calorimeter (the barrel was installed in December 2004 and EBC in February 2006). The group is now working on calorimeter commissioning, software development and validation, and optimization of the use of the calorimeter signals to reconstruct a measure jets.

Argonne and MSU have taken responsibility for the Level 2 Supervisor and Region-of-Interest Builder components of the Level 2 trigger. These custom electronics boards route a subset of the information from the detector system to the ATLAS High Level Trigger. The trigger system as a whole reduces the input event rate from 100kHz to a few kHz on the basis of the information from the RoIB and eventually, following further processing, to ~200 kHz for storage and physics analysis

Argonne is the central site for work on database and data management. The group has key responsibilities in the design and implementation of the I/O model which must provided distributed access to many petabytes of data for both event reconstruction and physics analysis.

The group is working on a variety of physics and performance topics. One focus in the group is to study physics processes which rely crucially on the performance of the ATLAS calorimeters to measure jets and missing transverse energy: QCD production of jets, TTbar pairs and beyond the standard model processes such as those involving extra dimensions or quark compositeness. As part of this focus we are involved in the optimization of the calorimeter response to jets (being proponents of the method based on cell energy density weighting) and are heavily involved in the ATLAS JetEtMiss Combined Performance group.