H.E.S.S.: a window to the high energy universe

High-Throughput Compute services to unlock the puzzle of cosmic rays

Earth is bombarded every day with high-energy cosmic rays – a type of small, electrically charged particles first discovered in 1912. The H.E.S.S. experiment (High Energy Stereoscopic System) is an array of five telescopes built in the Gamsberg Mountains of Namibia to identify cosmic ray sources and investigate how these tiny particles accelerate and travel through space.

The H.E.S.S. experiment started in 2003 and, so far, the team has found more than 70 sources of cosmic rays, most of them pulsar wind nebulae and supernova remnants. They also discovered a Peta-Electronvolt (PeV) particle accelerator in the Milky Way – a crucial piece of the puzzle of high-energy cosmic rays.

EGI is a great framework to perform our simulations on a larger scale, better than what could be achievable in local computing centres. It also allows us to transparently share our data among the collaboration.
Jean-Philippe Lenain

The collaboration is an effort of about 200 scientists, from 43 scientific institutions across 14 countries. Together they have published more than 100 papers and they won, in 2006, the Descartes Prize of the European Commission – the highest recognition for collaborative research.

Besides cosmic rays, “H.E.S.S. is also participating in the quest for dark matter, and also tries to answer fundamental questions, such as whether the speed of light is the same at all energies or not,” adds Mathieu de Naurois, the spokesperson of the H.E.S.S. consortium.

Computational challenges

The data collected by the telescopes in Namibia is stored in two computing centres, the CCIN2P3 in France, and the Max Planck Institut für Kernphysik in Heidelberg. At the CCIN2P3 alone, H.E.S.S. has about 2.1 PB of data stored in tape.

This data by itself means very little and the H.E.S.S. relies on Monte Carlo simulations to extract meaningful information about the properties of cosmic rays. They use two chains of ongoing simulations and one of them has been running on EGI High-Throughput Compute resources since 2012.

The consortium also uses EGI storage services to share calibrated telescope data between users who do not have access to the CCIN2P3 and the Max Planck computing centres.

The distributed computing operations of the H.E.S.S. experiment are managed by Jean-Philippe Lenain, an astrophysicist based at the Laboratory of Nuclear and High Energy Physics in Paris.

“EGI is a great framework to perform our simulations on a larger scale, better than what could be achievable in local computing centres,” says Lenain. “It also allows us to transparently share our data among the collaboration.”

Copyright : Julien Bolmont / Collaboration HESS / CNRS Photothèque

The H.E.S.S. experiment site in Namibia

Copyright : Julien Bolmont / Collaboration HESS / CNRS Photothèque

H.E.S.S. EGI usage

The H.E.S.S. experiment has access to 19,000 CPU slots in eleven sites (via hess-vo) and has about 2,000 High-Throughput Compute jobs running at any given time.

In the last 12 months, H.E.S.S. has consumed over 38 million HS06 CPU hours.

The data centres providing the compute resources to the H.E.S.S. experiment are:

  • France: GRIF, OBSPM, M3PEC Bordeaux, LAPP, CCIN2P3
  • Germany: DESY-Zeuthen
  • Poland: CAMK
  • Sweden: SWEGrid