Performance of the ATLAS trigger system in 2015

Area of Science:

• High-energy particle physics
• Collider physics

Background:

• The ATLAS experiment at the Large Hadron Collider (LHC) collects vast amounts of data from proton-proton collisions.
• A sophisticated trigger system is essential for filtering relevant events from the high collision rates.
• Upgrades were implemented during the LHC's first long shutdown to optimize data acquisition.

Purpose of the Study:

• To present an overview of modifications to the ATLAS trigger and data acquisition systems.
• To evaluate the performance of the trigger system and its components using 2015 data.

Main Methods:

• Analysis of proton-proton collision data recorded by the ATLAS experiment in 2015.
• Assessment of the trigger system's efficiency and performance metrics.
• Review of system changes implemented after the LHC's first long shutdown.

Main Results:

• The ATLAS trigger system successfully selected high-quality data at a reduced rate of approximately 1 kHz from up to 40 MHz of collisions.
• Performance evaluation confirmed the effectiveness of the trigger system and its components with the recorded data.
• The implemented system changes were integrated and functional during the 2015 data-taking period.

Conclusions:

• The ATLAS trigger and data acquisition systems were successfully upgraded and performed effectively during the 2015 LHC run.
• The system's ability to handle high collision rates and select significant events was validated.
• These findings contribute to the ongoing analysis of physics at the LHC.