Improving Trigger Rate Monitoring Tools at ATLAS – CURF Introduction: Connor Menzel

This semester, I will be working on a project with Dr. Tae Min Hong in the Department of Physics and Astronomy for the ATLAS Experiment, which is one of the four main experiments at the Large Hadron Collider at CERN in Geneva, Switzerland. To understand what my specific project entails and why it is important, I think it is best to first give a brief overview of the LHC and the ATLAS experiment.

The LHC is a particle accelerator, which means that it accelerates subatomic particles to near the speed of light in order to collide them. Colliding particles at high energies can create new particles which can then be observed by the detector. Scientists from around the world then use the data collected by the experiments to try to answer fundamental questions about the universe, such as the origin of mass and the nature of dark matter and dark energy. The most well-known discovery made by CERN is perhaps the discovery of the Higgs Boson, which is the force-carrying particle associated with the Higgs field, the field which essentially gives particles mass.

The ATLAS detector sees up to 1.7 billion collisions a second, which produces so much data that it would be impossible to store all of it, but luckily only a few of these events contain relevant data that the scientists care about. In order to select which events are important enough to save offline, ATLAS uses a two stage trigger system; the Hong group is one of the many groups that works on the research and development of this trigger system.

My project deals with a program called Xmon, a trigger monitoring tool that runs in the control room at ATLAS during runs of the LHC. Xmon makes predictions about how much data the triggers should be letting through, which allows problems with the trigger system to be easily spotted. You can see this graph as an example; the actual trigger rates are much higher than the predicted rates at the one spot in the middle, so something is most likely wrong with the trigger.

The spike in trigger rates in the middle shows that there is most likely an issue with the trigger

Xmon is essential in making sure the trigger system is operating properly, but there is still some functionality that can be added to Xmon to make it more effective, which is what I will be working on. I am currently writing additions to Xmon that allow it to be more easily tested, and will also allow for the detection of small deviations across multiple groups of triggers. My goal is to incorporate these changes by the end of the semester so they can be used in the next run of the LHC.

As of right now I see myself attending graduate school for a PhD in either physics or math after I graduate with the eventual goal to do some sort of research and teach. The CURF is giving me the amazing opportunity to do important research, which helps me figure out what I am really interested in doing for my career. I’m still not not sure exactly where my passions lie within the fields of physics and mathematics, but right now I am trying to learn as much as I can while enjoying every second of it.

To say a bit more about myself, I am majoring in physics and math, with a German minor as well. One unique thing about me is that I am a percussionist and I play snare drum in the Pitt Band. I have been playing drums since the fourth grade, and playing in the Pitt Band has been one of my favorite activities at college so far.

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