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ATLAS-Canada Prepares for Next Run of the Large Hadron Collider; Higher Intensity Predicted to Generate More Data


The eight torodial magnets can be seen on the huge ATLAS detector with the calorimeter before it is moved into the middle of the detector. This calorimeter will measure the energies of particles produced when protons collide in the centre of the detector. ATLAS will work along side the CMS experiment to search for new physics at the 14 TeV level. Image Courtesy of CERN.

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Reda Tafirout

In March 2015, the world’s largest particle accelerator, the Large Hadron Collider (LHC), will end a two-year shutdown and begin its second running phase, this time at a significantly higher collision energy level than before. Run 2, which will last three years, will restart at a record collision energy of 13 TeV, nearly double the beam intensity of the LHC’s initial running phase (2010-2013). One electron volt, or 1 eV is the energy generated from a single electron moving through a potential of 1 Volt. With the doubling of the LHC collision energy, the potential exists for new opportunities to find physics beyond the Standard Model and to broaden the Higgs physics program.

ATLAS-Canada, a partner in the international ATLAS experiment, has worked with Compute Canada since its inception to fully integrate Compute Canada computing facilities into the Worldwide LHC Computing Grid (WLCG). Since 2011, Compute Canada resource allocations have been instrumental in supporting ATLAS scientists’ work, including their major and historical discovery of a Higgs particle in July 2012.

This January, ATLAS-Canada was one of a handful of research groups in the country who received an allocation through Compute Canada’s inaugural RPP competition. In 2015, ATLAS Canada will have access to 3,378 core years of computational power and 3,164 TB of storage capacity on Compute Canada systems. This storage allication is expected to nearly double in 2017.

“The availability of Compute Canada resources is crucial to our continued contribution to the groundbreaking discoveries coming from the Large Hadron Collider,” says Reda Tafirout, a TRIUMF Research Scientist and ATLAS-Canada Computing Coordinator. “The computational needs for 2015-2017 remain very high as a much larger volume of data will be collected and generated during LHC Run 2 phase. The proton-proton collisions will occur at a much higher beam energy and intensity making analysis more complex. Significant computing resources will be required to analyze the data and to produce large-scale simulation samples in a timely fashion.”

Each year, the ATLAS experiment collects several Petabytes of raw data during LHC operations, and it produces numerous derived and simulated datasets that are of similar scale effectively on a continuous basis. The nature of ATLAS computing and its scale require the resources to be distributed across multiple sites so productivity does not come to a halt for a sustained period during either a scheduled maintenance, site expansion/consolidation, or other issues such as a security breach or service vulnerability.

As part of WLCG, there are two ATLAS Tier-2 federations based at Compute Canada facilities: one in the east and one in the west. SciNet (University of Toronto) and CLUMEQ (McGill University) facilities are used in the east, while in the west, WestGrid facilities at Simon Fraser University and the University of Victoria are used. Distributing Compute Canada resources for ATLAS across a few sites allows load balancing across sites and also leverages the knowledge accumulatedby the local technical experts.

“These resources allow us to meet our increasing commitments to ATLAS as more data are being generated, and allows Canadians to remain competitive on the world stage,” says Tafirout.

One of the priorities of the LHC Run 2 physics program is to determine whether the new boson discovered in 2012 is precisely the Higgs boson of the Standard Model, or possibly the lightest boson of several in an extended Higgs sector.

In addition, Canadian scientists will continue to lead a number of other important research investigations at ATLAS. These include the search for quantum black holes and strong gravity effects; the search for massive long-lived highly ionizing particle or a particle with a large electric charge; leading several important measurements in various collision event topologies and models; and preparing to measure the scattering of two massive vector bosons (VBS), which is a key process to probe the nature of electroweak symmetry breaking and allows to test if the Higgs sector is fully responsible to unitarize this amplitude.

“The coming years will provide access to the design energy and increased luminosity of the LHC and therefore mark a crucial time in the search for new physics,” says Tafirout. “The extra Canadian-only computing resources will have a high impact and will keep Canadians highly competitive in these exciting times for particle physics.”

Presently, the ATLAS-Canada collaboration consists of 39 faculty members at nine universities (plus ATLAS TRIUMF, Canada’s National Laboratory for Particle and Nuclear Physics), as well as 25 postdoctoral fellows, and 66 graduate students. This represents about half of the experimental particle physics community in Canada. The Canadian universities are University of Alberta, University of British Columbia, Carleton University, McGill University, Université de Montréal, Simon Fraser University, University of Toronto, University of Victoria, and York University. The overall ATLAS collaboration consists of about 3,000 researchers from 177 institutions in 38 countries (see

“The next three years will be very exciting for the ATLAS collaboration and it is important for Canada to remain a key player and contributor to the scientific output of the ATLAS experiment,” says Tafirout. “Canadians plan to build on the expertise and leadership that they demonstrated during Run 1 and are well equipped to make key contributions to ATLAS during Run 2.”