Mass Sensitive Observables of Simulated Cosmic Ray Air Showers

Interactions between high-energy cosmic rays, which are charged particles of astrophysical origin, and atmospheric nuclei produce extensive air showers, cascades of secondary particles and electromagnetic radiation, measurable at ground. Specific air shower observables, such as the depth of shower maximum and relative size of the air-shower muonic component, are sensitive to the mass of the primary cosmic ray particle and therefore provide an avenue for cosmic ray mass composition analyses. The separation power between proton, helium, oxygen, and iron cosmic rays was studied using exact knowledge of mass sensitive air shower observables determined from CORSIKA simulations at the sites of the IceCube Neutrino Observatory at the South Pole and the Pierre Auger Observatory in Argentina. Separation power between primaries was determined from a Fisher linear discriminant analysis where dependencies upon both energy and zenith angle were investigated. Combined knowledge of all studied mass sensitive observables yield promising mass separation power. This motivates equipping the next generation of air-shower arrays with multiple detection techniques for the simultaneous measurement of these shower observables.