For modern air-shower arrays, a singular distance from the shower axis is commonly used to estimate the energies of cosmic ray primaries.
The optimal distance — i.e. the distance that minimizes statistical and systematic uncertainty — is largely defined by the spacing between detectors in an array.
However, an energy dependence in this optimal distance may arise for some array configurations due to a complex interplay between array geometry, the type and dynamic range of the detectors, and the form of the function used to fit the lateral distribution of signals.
In such cases, the use of a single reference distance for showers of all sizes can result in significant, energy-dependent systematic and statistical uncertainties in the estimation of primary energy.
These uncertainties can translate into discrepancies in the reconstructed energy spectrum of ultra-high-energy cosmic rays on the order of those observed at the Pierre Auger and Telescope Array installations.
We present the full chain of analysis demonstrating the possible emergence of such discrepancies in the energy spectrum from the array properties and reconstruction effects.