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This is a compilation of acronyms frequently used in the ATLAS Trigger and Data Acquisition systems. The list emerged from listening to the presentations during the ATLAS TDAQ week at CERN, May 15-19, 2006. It is made up of the acronyms that were most commonly used. It is neither complete nor necessarily 100% correct. For a more comprehensive list, see the ATLAS TDAQ Glossary compiled by Marc Dobson from which this heavily draws.
TDAQ
Trigger /and Data Acquisition
ROS
Read-Out System - A sub-system of the ATLAS TDAQ responsible for reading out the ATLAS RODs and for supplying event fragments to the LVL2 and EB sub-systems.
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Sub-Farm Output - Part of the data collection which outputs to mass storage the complete events received from the EF.
LVL1
Level 1 Trigger - The ATLAS First Level Trigger system provides a hardware based first trigger decision using only a sub-set of an event's data (Calorimeter and Muon only).
Level 1 Calorimeter Trigger
SL
Sector Logic
PPM
Preprocessor Module
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Jet/Energy Module
CMM
Common Merger Module
High Level Trigger
HLT
High Level Trigger - Comprised of both the LVL2 and EF, the two ATLAS trigger levels that are implemented primarily in software.
LVL2
Level 2 Trigger - The ATLAS Second Level Trigger system provides a software based second stage trigger decision, to reduce the rate of triggers from LVL1 by about a factor of 100. It uses 'Regions of Interest' (RoI) as given by the LVL1 trigger to selectively read out only certain parts of the ATLAS detector hardware and computes a LVL2 trigger decision.
EF
Event Filter - The hardware and software required for the final stage of the on-line event selection, data monitoring and calibration using offline style algorithms operating on complete events accepted by LVL2.
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DDC
DCS to DAQ Communication
CTP
Central Trigger Processor - The component that generates the LVL1 Trigger
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Object Kernel Support - Package which provides a simple active persistent in-memory object manager which is used to implement run-time configuration databases.
Detector
Muon System
CSC
Cathode Strip Chamber
MDT
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Resitive Plate Chamber
TGC
Thin Gap Chamber
Inner Detector
ID
Inner Detector
SCT
Semiconductor Tracker
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Transition Radiation Tracker
Experimental Areas
UX15
Underground experimental area 15 (ATLAS cavern)
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Underground services area 15 (ATLAS electronics cavern)
Data Formats
AOD
Analysis Object Data - High-level analysis objects, such as traks and clusters. Elsewhere referred to as the "Micro DST".
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Trigger and Offline Board - Sub-committee of the EB.
Consists of:
ATLAS Management,
Computing and Software Coordinators,
Physics Coordinator,
TDAQ PLs,
Data Preparation Coordinator.