Trigger Menus for the ATLAS Second Level Trigger: Design of the Steering System

This note presents a scheme for the implementation of trigger menus, to be used in the LVL-2 pilot project. The scheme is based on the event characterization through physics signature formed by a co mbination of trigger elements. Most of the trigger elements will be based on the results of feature extraction algorithms using the full granularity data from different sub-detectors, where RoI info rmation from LVL-1 is used on most cases to 'guide' the LVL-2 system to detector regions with 'activity'. The scheme foresees one trigger menu to be visible for the user, where sequential selection of events can be achieved by a set of algorithm tables defining the operations to be executed in order to build the trigger elements at each processing step.