Sub-TeV hadronic interaction model differences and their impact on air showers

Á Pastor-Gutiérrez,R D Parsons,M Schmelling,H Schoorlemmer

doi:10.1140/epjc/s10052-021-09160-2

Abstract

In the sub-TeV regime, the most widely used hadronic interaction models disagree significantly in their predictions for post-first interaction and ground-level particle spectra from cosmic ray induced air showers. These differences generate an important source of systematic uncertainty in their experimental use. We investigate the nature and impact of model uncertainties through a simultaneous analysis of ground level particles and first interaction scenarios. We focus on air shower primaries with energies close to the transition between high and low energy hadronic interaction models, where the dissimilarities have been shown to be the largest and well within the range of accelerator measurements. Interaction models are shown to diverge as several shower scenarios are compared, reflecting intrinsic differences in the model theoretical frameworks. Finally, we discuss the importance of interactions in the energy regime where the switching between models occurs (<1 TeV) and the effect of the choice of model on the number of hadronic interactions within cosmic ray induced air showers of higher energies.

Highlights

In a recent study [2], it was found that for cosmic-ray protons with an energy just above the typical switching energy, the properties of the simulated extensive air showers (EASs) have a strong dependency on the selection of the hadronic interaction model
We focus on air shower primaries with energies close to the transition between high and low energy hadronic interaction models, where the dissimilarities have been shown to be the largest and well within the range of accelerator measurements
Through a detailed investigation of events initiated by 100 GeV protons we cast light on the sources of disagreement between hadronic interaction models [2]

Summary

Introduction

In a recent study [2], it was found that for cosmic-ray protons with an energy just above the typical switching energy, the properties of the simulated EASs have a strong dependency on the selection of the hadronic interaction model. With increasing energy of the incident proton (up to 100 TeV), the average differences in air shower properties between the models seemed to reduce. In this followup study, we focus on the switching energy domain, where the differences between the models are most prominently exposed (up to 60% difference in the ground level observables). A fraction of hadronic first interactions will generate an energetic π 0, which will subsequently generate an electromagnetic cascade, mimicking a gamma-ray induced air shower The rates of these events generated by different hadronic interaction models has a significant impact on sensitivity studies for gamma-ray observatories [3].

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