track finding Also Monte Tier 2: Universities algorithms. codes to produce and laboratories. Produce “large” full simulated data to physics files and evaluate efficiency of Note processing is stripped down experimental compute and data Analysis Object Data detection. intensive (AOD) files that are ~10% original size Physics Analysis Disk Files of Use simple statistical Data reduction and While the bulk of Physics Information to Information techniques (like processing steps with discoveries and data processing is Knowledge/Discovery including histogramming, advanced physics results are done at Tier 1 and accelerator and multi-variate analysis algorithms to identify confidential until Tier 2 resources, the Monte data. methods and other event properties, certified by end stage analysis is data analysis particle hypothesis etc. group and usually done by users Include wisdom techniques and model For interactive data presented at at a local Tier 3 from lots of fits to discover new analysis of those meeting/journal. physicists (papers) effects (particles) and reduced and selected Data preserved facility. The scale of in analysis choices put limits on effects data sets the classic so results computing resources not seen program is Root from reproducible at Tier 3 sites range CERN that reads from workstations to multiple event (AOD, small clusters. ROOT NTUP) files from is the most common selected data sets and software stack used use physicist generated C++ code to to analyze compact calculate new data formats quantities such as generated on implied mass of an distributed unstable (new) particle computing resources. Data transfer is done using ATLAS and CMS DDM tools, which mostly rely on gridFTP middleware. XROOTD based direct data access is also gaining importance wherever high network bandwidth is available. Figure 1: The LHC Collider location at CERN Figure 2: The Multi-tier LHC computing infrastructure Astronomy and Physics
track finding algorithms. Produce “large” full physics files and stripped down Analysis Object Data (AOD) files that are ~10% original size Also Monte codes to produce simulated data to evaluate efficiency of experimental detection. Tier 2: Universities and laboratories. Note processing is compute and data intensive Physics Analysis Information to Knowledge/Discovery Disk Files of Information including accelerator and Monte data. Include wisdom from lots of physicists (papers) in analysis choices Use simple statistical techniques (like histogramming, multi-variate analysis methods and other data analysis techniques and model fits to discover new effects (particles) and put limits on effects not seen Data reduction and processing steps with advanced physics algorithms to identify event properties, particle hypothesis etc. For interactive data analysis of those reduced and selected data sets the classic program is Root from CERN that reads multiple event (AOD, NTUP) files from selected data sets and use physicist generated C++ code to calculate new quantities such as implied mass of an unstable (new) particle While the bulk of data processing is done at Tier 1 and Tier 2 resources, the end stage analysis is usually done by users at a local Tier 3 facility. The scale of computing resources at Tier 3 sites range from workstations to small clusters. ROOT is the most common software stack used to analyze compact data formats generated on distributed computing resources. Data transfer is done using ATLAS and CMS DDM tools, which mostly rely on gridFTP middleware. XROOTD based direct data access is also gaining importance wherever high network bandwidth is available. Physics discoveries and results are confidential until certified by group and presented at meeting/journal. Data preserved so results reproducible Figure 1: The LHC Collider location at CERN Figure 2: The Multi-tier LHC computing infrastructure Astronomy and Physics