TY - JOUR

T1 - An overview of the ATLAS High Level Trigger Dataflow and Supervision.

AU - ATLAS, TDAQ authorlist

AU - Smizanska, Maria

N1 - "©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."

PY - 2004/6

Y1 - 2004/6

N2 - 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.

AB - 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.

U2 - 10.1109/TNS.2004.828875

DO - 10.1109/TNS.2004.828875

M3 - Journal article

VL - 51

SP - 361

EP - 366

JO - IEEE Transactions on Nuclear Science

JF - IEEE Transactions on Nuclear Science

SN - 0018-9499

IS - 3 Part

ER -