Use of High Performance Computing to Simulate Cosmic-Ray Showers Initiated by High-Energy Gamma Rays

Abstract

We use the supercomputer from the Laboratorio Nacional de Supercomputo del Sureste de Mexico (LNS) to simulate secondary cosmic-ray showers initiated by gamma rays with energies between 100 GeV and 100 TeV. These simulations play an important role in the search for gamma ray bursts (GRB) in ground observatories, such as the High Altitude Water Cherenkov (HAWC) observatory located in Sierra Negra, Mexico. GRB are the most energetic explosions observed so far in our Universe and they have been observed only in satellite detectors such as Fermi/GBM, Swift/BAT and INTEGRAL. Their observation in ground observatories will constitute an important scientific breakthrough in the field of astroparticle physics. We use MPI to run simulation code in parallel on hundreds of CPU cores from the LNS. In particular we use the CORSIKA Monte Carlo shower generator with zenith angles of the primary gamma rays between 0 and 45° and azimuth angles between 0 and 360° with an spectral index of −2. We report on benchmark results on the speed and scalability of our code as a function of the number of CPU cores. The authors are members of the HAWC Collaboration, they use high performance computing to analyze the data collected with the HAWC Observatory.