An Integrated Testing Facility for the Global Trigger of the CMS Experiment at CERN

The Global Trigger is part of the Level-1 Trigger of the CMS experiment at CERN, with the task to find the most interesting events corresponding to a rate of 100 kHz from the basic Large Hadron Collider interaction rate of 40 MHz. It is expected to render a decision within 3:2 $\mu$s, which necessitates an implementation using custom hardware. The implementation makes heavy use of Field Programmable Gate Array (FPGA) technology to reconcile the performance requirements with the need for exibility. The complexity of the Global Trigger system (13 boards with 51 FPGA chips) makes it vulnerable to a multitude of errors, from electrical errors such as bad solder joints or plug contacts up to logical errors in the implementation of the firmrmware and the configuration software. The goal of the work described in this thesis was to provide an integrated system that allows users to easily determine whether the system is working correctly and assists experts in tracking down the internal causes of such errors within the context of the Level-1 Trigger Online Control infrastructure. The operation of the testing system was validated on the basis of errors uncovered in the physics data collected during data taking on cosmic radiation in July and August 2009. The results demonstrate the importance of an easily available testing infrastructure and its integration into the experiment's operating procedure.