Study of ATLAS Transition Radiation Tracker performance with supercomputers and federated data storage system
After the early success in discovering a new particle consistent with the long awaited Higgs boson, the Large Hadron Collider (LHC) experiments have started the precision measurements and they are ready for further discoveries that will be made possible by much higher LHC collision rates during Run 2. ATLAS, one of the four experiments at the LHC, is leading a computing evolution program to evolve their software and computing model to make the best possible usage of available resources, including supercomputers. A proper understanding of the detectors performances at high occupancy condition is important for many on-going physics analyses. The ATLAS Transition Radiation Tracker (TRT) is one of these detectors.
TRT is a large straw tube tracking system that is the outermost of the three subsystems of the ATLAS Inner Detector (ID). TRT contributes significantly to the resolution for high-pT tracks in the ID providing excellent particle identification capabilities and electron-pion separation. ATLAS experiment is using Worldwide LHC Computing system (WLCG) GRID. WLCG is a global collaboration of computer centers and it provides seamless access to computing resources, which include data storage capacity, processing power, sensors, visualization tools and more. WLCG resources are fully utilized and it is important to integrate opportunistic computing resources such as supercomputers and federated data storage systems not to curtail the range and precision of physics studies.
One of the most important studies to be solved for ATLAS physics researches is the reconstruction of proton-proton events with large number of interactions in TRT. It becomes clear that high-performance computing contributions become important and valuable. An example of a very successful approach is National Research Centre Kurchatov Institute’s (NRC KI) Data Processing Center including Tier-1 GRID site, supercomputer and at the same time linked to the federated storage system.
The presented studies include TRT performance results obtained with the usage of the standard ATLAS GRID as well as Kurchatov Institute’s supercomputer and federated data storage system based on resources of NRC KI, Petersburg Nuclear Physics Institute and St.-Petersburg State University. In addition to a physics results the analysis of CPU efficiency during these studies is presented.