Trigger Presenter, the graphical user interface for online trigger monitoring in ATLAS

In the ATLAS experiment a highly selective trigger system is required to reduce the interactions rate of 1 GHz to about 100 Hz for data storage. It is based on three levels, Level 1 is hardware based, Level2 and Event Filter are software based (High Level Trigger, HLT). The full system is configurable and extremely flexible to meet the demands of the running experiment. Highly important component of the system is the trigger on-line monitoring. It includes rate monitoring, to ensure stable data taking, but also to give feedback for the trigger configuration design. In addition, it is of great importance to monitor the stability of the HLT PC farms. For this reason Trigger Presenter (TriP) has been designed. This Graphical User Interface provides relevant on-line information for the shifter and expert. It presents the trigger information in a user friendly way, and at the same time meets all the demands for Level1 and HLT high flexibility. It has been extensively used in the combined, cosmic and commissioning runs in 2007 and 2008. Moreover, it was used in the monitoring of the first beam events on the 10 September 2008 and will be used as the main trigger rate monitoring tool for collisions in 2009. Next release of TriP, called Trigger Rate Presenter (TRP) is in progress, expected to be used in spring 2009