60527912
Conditions and configuration metadata for the ATLAS experiment
In the ATLAS experiment, a system called COMA (Conditions/Configuration Metadata for ATLAS), has been developed to make globally important run-level metadata more readily accessible. It is based on a relational database storing directly extracted, refined, reduced, and derived information from system-specific database sources as well as information from non-database sources. This information facilitates a variety of unique dynamic interfaces and provides information to enhance the functionality of other systems. This presentation will give an overview of the components of the COMA system, enumerate its diverse data sources, and give examples of some of the interfaces it facilitates. We list important principles behind COMA schema and interface design, and how features of these principles create coherence and eliminate redundancy among the components of the overall system. In addition, we elucidate how interface logging data has been used to refine COMA content and improve the value and performance of end-user reports and browsers.
61118032
An extensible infrastructure for querying and mining event-level metadata in ATLAS
The ATLAS event-level metadata infrastructure supports applications that range from data quality monitoring, anomaly detection, and fast physics monitoring to event-level selection and navigation to file-resident event data at any processing stage, from raw through analysis object data, in globally distributed analysis. A central component of the infrastructure is a distributed TAG database, which contains event-level metadata records for all ATLAS events, real and simulated. This resource offers a unique global view of ATLAS data, and provides an opportunity, not only for stream-style mining of event data, but also for an examination of data across streams, across runs, and across (re)processings. The TAG database serves as a natural locus for run-level and processing-level integrity checks, for investigations of event duplication and other issues in the trigger and offline systems, for questions about stream overlap, for queries about interesting but out-of-stream events, for statistics, and more. In early ATLAS running, such database queries were largely ad hoc, and were handled manually. In this paper, we describe an extensible infrastructure for addressing these and other use cases during upload and post-upload processing, and discuss some of the uses to which this infrastructure has been applied.
177869142
Event selection services in ATLAS
ATLAS has developed and deployed event-level selection services based upon event metadata records (TAGS) and supporting file and database technology. These services allow physicists to extract events that satisfy their selection predicates from any stage of data processing and use them as input to later analyses. One component of these services is a web-based Event-Level Selection Service Interface (ELSSI). ELSSI supports event selection by integrating run-level metadata, luminosity-block-level metadata (e.g., detector status and quality information), and event-by-event information (e.g., triggers passed and physics content). The list of events that survive after some selection criterion is returned in a form that can be used directly as input to local or distributed analysis; indeed, it is possible to submit a skimming job directly from the ELSSI interface using grid proxy credential delegation. ELSSI allows physicists to explore ATLAS event metadata as a means to understand, qualitatively and quantitatively, the distributional characteristics of ATLAS data. In fact, the ELSSI service provides an easy interface to see the highest missing ET events or the events with the most leptons, to count how many events passed a given set of triggers, or to find events that failed a given trigger but nonetheless look relevant to an analysis based upon the results of offline reconstruction, and more. This work provides an overview of ATLAS event-level selection services, with an emphasis upon the interactive Event-Level Selection Service Interface.
62529453
Emerging Database Technologies and Their Applicability to High Energy Physics: A First Look at SciDB
Traditional relational databases have not always been well matched to the needs of data-intensive sciences, and to the needs of high energy physics data stores in particular. To address this mismatch, members of the database community and people involved with large scientific data stores in a variety of disciplines have inaugurated an open-source project, SciDB, that aims to develop and deliver database technologies suited to the needs of data-intensive sciences. This paper describes early experience using the first release of SciDB with an initial subset of high energy physics data structures and query patterns. It examines the early capabilities of SciDB, and describes requirements that further development must address if emerging database technologies such as SciDB are to accommodate the data structures, query patterns, computations, and use cases of high energy physics.
62502797
Engineering the ATLAS TAG Browser
ELSSI is a web-based event metadata (TAG) browser and event-level selection service for ATLAS. In this paper, we describe some of the challenges encountered in the process of developing ELSSI, and the software engineering strategies adopted to address those challenges. Approaches to management of access to data, browsing, data rendering, query building, query validation, execution, connection management, and communication with auxiliary services are discussed. We also describe strategies for dealing with data that may vary over time, such as run-dependent trigger decision decoding. Along with examples, we illustrate how programming techniques in multiple languages (PHP, JAVASCRIPT, XML, AJAX, and PL/SQL) have been blended to achieve the required results. Finally, we evaluate features of the ELSSI service in terms of functionality, scalability, and performance.
118584428
Turbulent Convection Model in the Overshooting Region. II. Theoretical Analysis
Turbulent convection models (TCMs) are thought to be good tools to deal with the convective overshooting in the stellar interior. However, they are too complex to be applied to calculations of stellar structure and evolution. In order to understand the physical processes of the convective overshooting and to simplify the application of TCMs, a semi-analytic solution is necessary. We obtain the approximate solution and asymptotic solution of the TCM in the overshooting region, and find some important properties of the convective overshooting. (1) The overshooting region can be partitioned into three parts: a thin region just outside the convective boundary with high efficiency of turbulent heat transfer, a power-law dissipation region of turbulent kinetic energy in the middle, and a thermal dissipation area with rapidly decreasing turbulent kinetic energy. The decaying indices of the turbulent correlations k, (u'T-r') over bar, and (T'T') over bar are only determined by the parameters of the TCM, and there is an equilibrium value of the anisotropic degree.. (2) The overshooting length of the turbulent heat flux (u'T-r') over bar is about 1H(k) (H-k = vertical bar dr/d ln k vertical bar). (3) The value of the turbulent kinetic energy at the convective boundary k(C) can be estimated by a method called the maximum of diffusion. Turbulent correlations in the overshooting region can be estimated by using kC and exponentially decreasing functions with the decaying indices.