Organized by: Prof. Lu Lu

Events on Thursday, September 25th, 2025

Recent Advances in Modeling Cosmic Ray Observations and New Developments in Telescope Array Data Analysis

Time: 2:30 pm - 3:30 pm

Place: Chamberlin 5280

Speaker: Anatoli Fedynitch, Academia Sinica, Taiwan

Abstract: Understanding the cosmic ray flux is essential across astroparticle physics. The observed spectrum and mass composition provide critical inputs for modeling atmospheric muons and neutrinos, dominant backgrounds in neutrino observatories, and for applied fields such as muon tomography. In 2017, we introduced the Global Spline Fit (GSF), an agnostic framework designed to let data guide the modeling with minimal assumptions. Nearly a decade later, new results from space-based observatories (AMS, DAMPE, CALET) and dedicated measurements near the knee (GRAPES, LHAASO) enable a substantial update. I will present the next-generation GSF2025 and discuss its implications for our global view of cosmic rays from GeV to EeV. In the second part of the talk, I will highlight our group’s ongoing effort to reinvent the analysis chain of the Telescope Array surface detectors. Leveraging deep neural network–based reconstruction, we address systematic uncertainties that stem from the unknown mass composition, achieving significant improvements in energy and angular resolution. This approach also opens new possibilities for inferring primary mass and Xmax in future iterations. To rigorously propagate uncertainties, we have developed a Bayesian forward-folding framework that naturally incorporates both intrinsic and external constraints into the measurement’s error bands.

Host: Lu Lu

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