Optimisation of Level 1 Topological Trigger Cuts for B-physics in ATLAS Detector

Triggers are important in detector systems as they select the most interesting events to be investigated from the huge amount of data coming out every second. In the ATLAS detector, the rate of events occuring was 20MHz in Run 1 data taking, while in Run 2, the rate will be increased to 40MHz. This imposes a great pressure on the trigger system as the time needed to process one event is roughly constant in the Data Acquisition (DAQ) System. More eective triggering conditions have to be imposed in order to reduce the rate of events passing the rst level of the triggering system. In this project, the main goal is to nd out the most eective set of triggering conditions, in order to build a suitable menu for a wide range of B-physics anlayses to be performed in Run2. The organisation of the report is as follows: the ATLAS trigger system and data/MC samples are discussed in Section 2 and 3 respectively. Then the analysis for 1-dimensional topological cuts is described and the corresponding result is presented in Section 4. Then for further improvement in eectiveness of triggering conditions, the 2-dimensional cuts are analyzed in Section 5. Finally in Section 6, conclusion of the project is made and some possible future improvements are mentioned.