The LHC Physics Center at Fermilab concluded the summer HATS (Hands-on Advanced Tutorial Session) season on July 26-27 with a new “Particle Flow LEGO HATS.” This new course was designed by Florida State University Associate Professor Andrew Askew and Bethel University Assistant Professor Julie Hogan. Construction was done by Askew and FSU graduate student De-lin (Mac) Xiong, and key components were provided by the FSU Physics Department machine shop. The course gives participants a good grasp of the reconstruction process, called particle flow, that leads to the identification of each final state particle in a CMS event.
Here, one simulated 13-TeV proton-proton collision in CMS is simplified so that calorimeter energies can be expressed using Lego toy bricks. The yellow fishing line represents the charged particle tracks in the silicon tracker. The model is designed with momentum and position information recorded on each brick or track. The tutorial is truly hands-on as the students can remove the calorimeter deposits and tracks to record the detector information, a step equivalent to CMS data acquisition. Using the Lego brick height to identify “seeds,” the students clustered the energy deposits by hand, performing the particle flow reconstruction that is normally done by CMS software. By the end of Friday afternoon, the student group was able to identify the particles and event features and were shown the associated CMS event display to validate their (correct!) answer.
Cecilia Gerber and Sergo Jindariani are co-coordinators of the LHC Physics Center at Fermilab. Marguerite Tonjes provides user support at the LHC Physics Center.
This shows the beamline view of the CMS event model. Blue represents energy in the hadron calorimeter, red represents energy in the electromagnetic calorimeter, and yellow represents particle tracks (not shown curved, as they would be due to the magnetic field). Photo: Marguerite Tonjes
