CLIC and ILC: new windows into the subatomic world

High-Throughput Compute solutions for linear colliders

The Large Hadron Collider (LHC) operated by CERN has been home to some of the most interesting discoveries in high-energy physics. Thousands of scientists work on the data collected by detectors placed around the circumference of the LHC and their successes are well known, with the Higgs particle as highlight.

But there is more physics to be discovered and the LHC is not the only window into the subatomic world.

The Compact Linear Collider Study (CLIC) and the International Liner Collider (ILC) are two collaborations set up to explore what happens when electrons and positrons (which are antielectrons) collide at high-energy. Using electrons and their antiparticles instead of protons (like the LHC experiments) will allow scientists to collect a new range of high-precision measurements of the Higgs boson and to get a different view on the high-energy physics.

Both collaborations bring together hundreds of scientists from multiple institutes and countries. They have succeeded in designing detectors that are now validated and ready for construction. CLIC is one of the options for the next collider to be built near CERN at the border between France and Switzerland. The ILC is proposed by an international collaboration with Japan as a host country and is currently negotiated on the political level for a timely start-up.

EGI + CLIC and ILC

The ILC virtual organisation (VO) was set up ten years ago to provide the computing and storage resources for the ILC collaboration. Both CLIC and ILC have used EGI High-Throughput Compute to simulate and reconstruct tens of millions of collision events during the design, testing and validation phases. The simulations helped the teams to evaluate and fine-tune the physics capabilities of the detectors.

In 2016, the ILC VO ran about 8 million computing jobs and consumed over 220,000,000 CPU hours (measured in elapsed HEPSPEC06 hours in the EGI Accounting Portal).

The EGI data centres (full list below) and non-EGI data centres providing the computing and storage to the ILC VO are located at CERN, DESY, RAL, KEK and PNNL.

Important contributions where made by all the supporting national e-infrastructures of: France, Germany, Israel, Poland, Portugal, Spain, United Kingdom as well as the US and the AsiaPacific region.

The biggest challenge at the moment is to optimise the processing and analysis of the collision events. Every collision simulation consumes a lot of computing time to simulate and reconstruct. The ideal scenario is to have large files to minimize the number of High-Throughput Compute jobs. But on the other hand, large files may lead to problems with queue length limitations at the data centre level. Improving these splitting and merging processes is one area of improvement.

Data centres supporting the ILC VO

The EGI federated data centres that provide compute and storage resources to the ILC VO are:

CERN-PROD

CYFRONET-LCG2

DESY-HH

DESY-ZN

GRIF

IFCA-LCG2

IL-TAU-HEP

IN2P3-CC

IN2P3-LAPP

JP-KEK-CRC-02

RAL-LCG2

TECHNION-HEP

UKI-LT2-Brunel

UKI-LT2-IC-HEP

UKI-LT2-QMUL

UKI-LT2-RHUL

UKI-NORTHGRID-LIV-HEP

UKI-NORTHGRID-MAN-HEP

UKI-SCOTGRID-DURHAM

UKI-SCOTGRID-ECDF

UKI-SCOTGRID-GLASGOW

UKI-SOUTHGRID-BHAM-HEP

UKI-SOUTHGRID-BRIS-HEP

UKI-SOUTHGRID-CAM-HEP

UKI-SOUTHGRID-OX-HEP

UKI-SOUTHGRID-RALPP

UNI-FREIBURG

WEIZMANN-LCG2

Frontview of a collision event registered at the ILC.

Credit: Akiya Miyamoto.

(The HEP-fluent reader will perhaps recognise this as a e+e -> Zh -> qqh event).

ILC VO usage (2016)
  • ~220 million hours of compute time (normalised elapsed time in HEPSPEC06)
  • ~8 million submitted jobs
  • ~110 active users
CLIC and ILC’s EGI services
ILC VO providers

Important contributions where made by all the supporting national e-infrastructures of: France, Germany, Israel, Poland, Portugal, Spain, United Kingdom as well as the US and the AsiaPacific region.