A Multi-Level Parallel Pipeline for SPHERE-3 Detector Simulation: From EAS Generation to Image Approximation

TL;DR

This paper presents a multi-level parallel pipeline for simulating the SPHERE-3 detector, enabling efficient processing of extensive air shower events for cosmic ray research through optimized, thread-safe computational stages.

Contribution

It introduces a scalable, multi-step simulation pipeline combining CORSIKA, C++/OpenMP, Geant4 MT, and Python, optimized for parallel processing without locks.

Findings

Linear scaling achieved with parallel processing.

Thread safety ensured through architectural design.

Efficient simulation of cosmic ray events.

Abstract

Optimization of the SPHERE-3 detector configuration, designed to study the mass composition of primary cosmic rays in the energy range 1--1000 PeV by registering Cherenkov light reflected from the snow surface, requires simulation of a large number of extensive air shower events. A software suite with a multi-step computational pipeline is presented: shower generation in CORSIKA, decoding and cloning of events (C++/OpenMP), ray-tracing of optical photons through the detector model (Geant4 MT), and approximation of images by a lateral distribution function (Python/multiprocessing, iminuit). The key property of the problem is its natural atomicity: each event is processed independently at all stages, which provides linear scaling under parallel computation. Thread safety is achieved by architectural means -- shared data are read-only, mutable state is isolated per-worker -- without the use of locks on hot paths.