An overview of the ATLAS High Level Trigger Dataflow and Supervision.

ATLAS, TDAQ authorlist and Smizanska, Maria (2004) An overview of the ATLAS High Level Trigger Dataflow and Supervision. IEEE Transactions on Nuclear Science, 51 (3 Part). pp. 361-366. ISSN 0018-9499

[thumbnail of getPDF.pdf]
PDF (getPDF.pdf)

Download (182kB)


The ATLAS high-level trigger (HLT) system provides software-based event selection after the initial LVL1 hardware trigger. It is composed of two stages, the LVL2 trigger and the event filter (EF). The LVL2 trigger performs event selection with optimized algorithms using selected data guided by Region of Interest pointers provided by the LVL1 trigger. Those events selected by LVL2 are built into complete events, which are passed to the EF for a further stage of event selection and classification using off-line algorithms. Events surviving the EF selection are passed for off-line storage. The two stages of HLT are implemented on processor farms. The concept of distributing the selection process between LVL2 and EF is a key element in the architecture, which allows it to be flexible to changes (luminosity, detector knowledge, background conditions, etc.) Although there are some differences in the requirements between these subsystems there are many commonalities. An overview of the dataflow (event selection) and supervision (control, configuration, monitoring) activities in the HLT is given, highlighting where commonalities between the two subsystems can be exploited and indicating where requirements dictate that implementations differ. An HLT prototype system has been built at CERN. Functional testing is being carried out in order to validate the HLT architecture.

Item Type:
Journal Article
Journal or Publication Title:
IEEE Transactions on Nuclear Science
Additional Information:
"©2004 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE." "This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder."
Uncontrolled Keywords:
?? nuclear energy and engineeringelectrical and electronic engineeringnuclear and high energy physicsqc physics ??
ID Code:
Deposited By:
Deposited On:
01 May 2009 14:36
Last Modified:
21 Dec 2023 00:09