High Energy Physics at the ATLAS experiment.
Sten Hellman, Dept. of Physics

The Stockholm university elementary particle physics group is a member of the ATLAS collaboration at the CERN LHC accelerator. The experiment is being assembled at CERN, Geneva, Switzerland, datataking is to start in 2007. The group is involved in two detectorparts: the digitization electronics of the TILE calorimeter and the first level calorimeter trigger of the experiment. The TILE calorimeter is the subdetector which will measure the energy of strongly interacting particles. The group is responsible for the manufacturing, installation and maintenance of the electronics which converts the analouge signals coming out of the detector two digital data suitable for computer read-out. The first level calorimeter trigger reduces the data rate from the 40 MHz given by the bunch crossing frequency to 100 kHz, a rate which will subsequently be reduced by higher trigger levels to reduce the rate for full data storage to about 200 Hz. In addition to its committment to the construction of the experiment the Stockholm group is participating in physics analyses. We concentrate in two fields: searches for supersymmetric particles and test of the standard model through precision measurements of properties of the top quark and the intermediate vector bosons. A PhD student joining the group will get academic training in topics relevant for the field, like quantum field theories, advanced statistical methods and analysis methods using up-to-date informatics methods, including the so called GRID technology. A student will also get training in and participate in the maintenance and commissioning of the advanced electronics used in the experiment. Most of the time during the education will be spent participating in analysis of physics data which will be pursued in collaboration with the other members of the research group. A PhD student in particle physics is expected to be able to spend a substantial fraction of her/his time at the CERN laboratory. The ATLAS detector is a large international colllaboration consisting of almost 1500 physicists from 34 countries. When the LHC accelerator turns on in 2007 it will provide proton-proton collisions at energies close to ten times higher than previously obtained. There are many outstanding questions in the so called Standard Model for elementary particle physics which will most probably be answered by the results from the experiment. It is expected that results from the LHC experiments will substantially increase our understanding of the smallest constituents of matter and the interactions between them.