Project F3:
"Quantification of primary cosmic-ray interactions"

Project Description

Hadronic interactions are crucial for understanding the universe at high energies, as they play a significant role from the sources of cosmic rays to the signals detected. We focus on two key scenarios in CIM: (1) high-energy particles interactions with thin, relatively stationary targets to produce secondary particles, which provide insights into both the inner structure of matter and the cosmic origin of the parent particles; (2) cascades of interactions when high-energy particles are observed on Earth in large natural media such as the atmosphere, water, ice, or rock. The aim of Project F3 is to study in detail the initial interaction of primary cosmic rays in the atmosphere.
During Phase 1, we performed a number of independent absolute measurements of energy spectra of cosmic-ray products, precision measurement of the production spectra of pions and kaons in proton–proton collisions and developed a tool for running air shower simulations for the prediction of atmospheric lepton fluxes.
The aim of Phase 2 is to achieve a better understanding of the first interaction of cosmic rays in the atmosphere by combining our results from Phase 1, to address the following questions:

1. Are the production cross sections that contribute to the atmospheric lepton fluxes modified in nuclear collisions at high energies?
2. What are the contributions from pions and kaons to the fluxes and is there a contribution from the decay of charmed mesons?
3. Is it possible to consistently describe the fluxes of leptons in the atmosphere and extensive air showers using standard model physics?