[Paper Review] AIRES A system for air shower simulations. User's guide and reference manual

Sergio J Sciutto|arXiv (Cornell University)|Nov 17, 1999

Astrophysics and Cosmic Phenomena88 citations

TL;DR

AIRES 19.04.00 is a comprehensive, open-source simulation system for high-energy cosmic ray air showers, modeling full space-time particle propagation with realistic atmospheric, geomagnetic, and Earth curvature effects. It employs unbiased thinning to handle large particle multiplicities and supports detailed physics including electrodynamics, hadronic interactions, decays, and propagation, with enhanced capabilities via extensible modules like ZHAireS for radio emission simulation.

ABSTRACT

The AIRES (AIR-shower Extended Simulations) system is a set of programs and subroutines to realistically simulate particle showers produced after the incidence of high energy cosmic rays on the Earth's atmosphere, and to manage all the related output data. The current version includes a series of improvements with respect to previous releases that are explained in detail in this manual and/or the web site aires.fisica.unlp.edu.ar from where the software can be downloaded. Among such improvements, it is worth mentioning: (i) High energy hadronic collisions can be simulated usign the the well-known hadronic models EPOS, QGSJET, or SIBYLL, all of them in their LHC-tuned versions. (ii) Detailed simulation of unstable hadron decays. (iii) The inclusion of a series of pre-compiled, ready to use, external special particle modules, that are characteristic of AIRES since its early versions. Such modules allow, for example, to easily simulate multi-primary particle showers. (iv) An exhaustive revision of the atmospheric profile models, including annual average profiles for geographcal locations corresponding to currently in operation ultra-high energu shower observatories; and also the capability of accepting user-defined custom atmospheric profiles.

Motivation & Objective

• To provide a reliable, extensible simulation framework for high-energy cosmic ray air showers across energies from <1 GeV to >1 ZeV.
• To model full space-time development of air showers with accurate atmospheric, geomagnetic, and curvature effects.
• To support unbiased statistical sampling (thinning) to maintain accuracy in high-multiplicity showers.
• To enable flexible input control via the Input Directive Language (IDL) and efficient job management through the AIRES Runner System.
• To extend simulation capabilities via plug-in modules, such as ZHAireS for radio emission modeling.

Proposed method

• Uses the Input Directive Language (IDL) to configure simulation parameters, including primary particle, energy, site, and physics models.
• Implements full space-time propagation of particles, accounting for energy loss, multiple scattering, and geomagnetic deflection.
• Applies unbiased thinning algorithms to manage large particle multiplicities without biasing average observables.
• Integrates external hadronic interaction models (e.g., EPOS, QGSJET, SIBYLL) via modular interfaces.
• Utilizes the AIRES Runner System for job coordination and monitoring in UNIX environments.
• Processes output via the AIRES summary program and object library for analysis of particle data, observables, and compressed output files.

Experimental results

Research questions

• RQ1 How can air shower simulations be made accurate and efficient across a wide energy range, from GeV to ZeV?
• RQ2 What is the optimal way to implement unbiased thinning in high-multiplicity air shower simulations?
• RQ3 How can the simulation system be extended to include new physics, such as radio emission from showers?
• RQ4 What are the most effective methods for managing complex simulation workflows in high-performance computing environments?
• RQ5 How can realistic atmospheric and geomagnetic fields be consistently modeled in air shower simulations?

Key findings

• AIRES 19.04.00 supports primary particles from 1 GeV to >1 ZeV, including all standard model particles up to Z=36.
• The system includes new atmospheric models (SouthPoleAvg, MalargueAvg) and supports user-defined models via AddAtmosModel.
• Special primary modules now allow dynamic setting of primary energy, removing the need for fixed PrimaryEnergy directives.
• The system now supports installation of extensions, such as ZHAireS, for simulating radio emission from air showers.
• New output tables (e.g., 6296 for secondary neutrinos) and improved random number generators (urandomt) enhance data fidelity and reproducibility.
• The system maintains full backward compatibility while introducing significant algorithmic and architectural improvements over version 18.09.00.