Abstract
The HL-LHC, the planned high luminosity upgrade for the LHC, will increase the collision rate in the ATLAS detector approximately a factor of 5 beyond the luminosity for which the detectors were designed, while also increasing the number of pile-up collisions in each event by a similar factor. This means that the level-1 trigger must achieve a higher rejection factor in a more difficult environment. This presentation discusses the challenges that arise in this environment and strategies being considered by ATLAS to include information from the tracking systems in the level-1 decision. The main challenges involve reducing the data volume exported from the tracking system for which two options are under consideration: a region of interest based system and an intelligent sensor method which filters on hits likely to come from higher transverse momentum tracks.
Highlights
The first level is implement in hardware with a decision latency of 2.5 μs
The L2 trigger is implemented in software on commercial PCs connected via a network to the Readout Out Subsystems (ROSs)
In addition to the track isolation and muon resolution described above, an L1-track trigger could be used for track-shower matching in electron identification and for b-jet tagging
Summary
The current ATLAS trigger [1] is a three level system. The first level is implement in hardware with a decision latency (including the time to return the decision to the detect front-ends) of 2.5 μs. The L2 trigger is implemented in software on commercial PCs connected via a network to the ROSs. Each L2 processor can request a subset of the total data in order to make decisions. Each L2 processor can request a subset of the total data in order to make decisions This subset is generally a region around an object, e.g. e/γ, μ, τ defined by the L1. These regions are referred to as Regions of Interest or ROIs. The L2 accepts 3-5 KHz of events for which the full event is built from the data buffered in the ROSs and propagated to the third level of the trigger called the event filter, EF. That is if an event is rejected by L1 it cannot accepted by later levels
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
