Cosmic ray mass composition study using upcoming PBR experiment framework

Dr. Diksha Garg

Indirect detection methods are used for observing very-high-energy (VHE) cosmic rays (above 1 PeV), by observing extensive air showers (EASs) produced from cosmic ray interaction with the Earth's atmosphere. This method of detecting EASs introduces uncertainties in determining the cosmic ray mass composition. Current understanding suggests that cosmic rays below 1 PeV are predominantly lighter elements, while VHE cosmic rays consist of a mix of heavier elements. The upcoming POEMMA-Balloon with Radio (PBR) mission will use a super-pressure balloon at an altitude of 33 km, equipped with a hybrid detection system comprising radio, fluorescence, and Cherenkov detectors. This multi-detector approach provides complementary measurements, potentially reducing uncertainties in various shower parameters. PBR is also capable of detecting high-altitude horizontal air showers (HAHAs), which are beyond the reach of ground-based experiments. To investigate the impact of different cosmic ray mass compositions on shower parameters, I propose using the CORSIKA 8 simulation package. This study will focus on two primary cosmic ray compositions: proton and iron. By simulating various quantities detectable by PBR for HAHAs, such as muon and electron/positron counts and shower maximum, we aim to perform an event-by-event mass separation between proton and iron primaries using Fisher linear discriminant analysis. This approach will help understand the relationship between cosmic ray composition and observable shower characteristics, potentially improving our understanding of VHE cosmic ray sources.