UJ researchers tuning CERN’s computers for the new Higgs decay to bottom quarks result

​Powerful computer systems made possible the new CERN observation of the Higgs boson decay to bottom quarks, which validates a new section of the Standard Model in Physics.

These computers crunch the immense amount of data pouring out of CERN 24 hours a day, and require ‘super-tuning’ to keep up. The University of Johannesburg (UJ) researchers’ group at ATLAS shed light on pioneering high-performance computing techniques harnessed for the global experiment.

The observation of the Higgs boson in a new decay mode connecting it to bottom quarks, and in a new production mode associated to vector bosons (heavy light), validates a new section of the Standard Model in a very exciting way. CERN made the announcement on Tuesday 28 August.

The standard model is for Physics, what DNA is for bioscience. Observing this decay fills in one of the big missing pieces of knowledge of the Higgs sector. It can ultimately reveal new physics Beyond the Standard Model (BSM) if there are unexplained differences to the Standard Model predictions.

The new discovery announced on 28 Aug was made possible by very powerful computers crunching the immense amount of data pouring out of CERN.

“While the result is certainly a confirmation of the Standard Model, it is equally a triumph for our analysis teams,” says Karl Jacobs, ATLAS Spokesperson. “During the early preparations of the Large Hadron Collider (LHC), there were doubts on whether this observation could be achieved.

“Our success is thanks to the excellent performance of the LHC and the ATLAS detector as well as the application of highly sophisticated analysis techniques to our large dataset,” he adds.

UJ researchers at CERN

Simon Connell coordinates the group of UJ researchers who are members of the global ATLAS experiment at CERN.

“The overall ATLAS team is made up of over 3,000 scientists all over the world, who are running searches for new particles, processing data and performing computer simulations. They also develop all aspects of the detector and computing systems – 24 hours a day, every day of the year,” says Connell. He is a Physics researcher at the University of Johannesburg.

The ATLAS high performance computing cluster, which is the nerve centre of the ATLAS detector, is where our group makes an on-going contribution,” explains Connell.

“An UJ staff member has worked on the Trigger and Data Acquisition (TDAQ) Computer system for the past decade.”

New techniques for super-tuning

Haydn du Plessis is a UJ member of the ATLAS team fine-tuning the computing cluster.

“Acquiring the huge amounts of data at ATLAS, fast enough to keep up, is pioneering new trends in modern computing. The challenge is really acute in the nerve centre, a very large TDAQ computing farm,” says Du Plessis.

Du Plessis is exploring the containerisation and virtualisation of the computer farm into thousands of number-crunching tasks on the cluster. This way, each task runs independently of the others, using the available resources as efficiently as possible. With his group, he is developing new techniques, inspired by Google research.

“We expect containerisation and virtualisation will make the cluster dramatically more flexible, which is significant for CERN. It is another way of getting more performance out of the same physical infrastructure.”

South Africa benefits from global collaboration

These advanced computing techniques have been shared with both the University and to the country, says Connell.

“Researchers trained at CERN transfer expertise to national IT systems in the countries they come from,” he says.

The Physics research at CERN also benefits other countries, he adds.

“The UJ group at CERN is part of an ATLAS team that searches for the (possible) force carrier particles associated with dark matter, known as the dark vector boson(s).

“Dark Matter is five times more abundant than normal matter, and permeates galaxies and solar systems. Its study is an important aspect of the Square Kilometre Array (SKA) programme, the global project which is building the biggest radio telescope in the world. These searches compliment the large South African astrophysical science endeavours,” says Connell.

The UJ group at CERN

The 28 Aug discovery is about the ‘Standard Model’ in Physics. The UJ work at ATLAS has supported key sections of detector operations and performance, with a search focus on Beyond Standard Model physics. The group contributes in the fields of Physics, Engineering and Technical support.

The UJ group members also contributed to the tools for searching for missing transverse in energy for detector performance; as well as development of display software for the Moun Subdetector System in the ATLAS Detector Control Centre.

The UJ group contributes to two other projects at ATLAS as well. In the first one, they participate in the search for a possible new force particle that is expected to be associated with dark matter, and also to the search for Higgs decays to “invisible” particles. Here the ATLAS detector constrains the branching ratio of a Higgs decaying to possible dark matter candidates.

The group is also contributing to Radiation Hard Humidity Sensors for the upgraded Inner Tracker. There is as yet no commercial solution for such sensors. These have the potential to lead to a novel sensing technology for extreme environments, such as space, medicine and nuclear energy.


Uj’s Prof Connell
Prof Azwinndini Muronga (Left), Immediate Past-president of South African Institute of Physics (SAIP), awards UJ’s Prof Simon Connell (Right) with an honorary membership in July 2017.
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