ATLAS celebrates results of 1000 collision papers

18 June 2021 | By

The ATLAS Collaboration celebrates the creativity, wealth and scientific impact enshrined in its 1000 papers using LHC collision data. This work – together with that carried out by its sister experiments at the LHC – represents a diversified physics programme that is unprecedented and unequalled in physics research to date.

On 18 June 2021, the ATLAS Collaboration submitted for publication its 1000th paper studying collision data from the Large Hadron Collider (LHC). It has been over a decade since the LHC started colliding beams of particles at record energies. In that time, it has produced the greatest wealth of physics data ever accumulated by a particle collider.

This treasure-trove of information about our Universe has been tirelessly explored by ATLAS physicists. Their scientific contributions cover a broad range of subjects, including the discovery of the Higgs boson and the study of its properties; the observation and measurement of previously uncharted high-energy processes; precise measurements of the properties and production rates of fundamental particles; the exploration of flavour and heavy-ion physics; deep and broad searches for new physics phenomena; and the development of countless new analysis methods and algorithms. Explore ATLAS’ research programme in the timeline below.

Today's milestone is an opportunity to spotlight the work of thousands of ATLAS Collaboration members – both current and former – who have contributed to these papers. Be it through work on detector construction, maintenance and operation, data analysis, trigger, software and computing, or the many other tasks necessary for ATLAS data-taking and exploitation, these papers are the result of a team effort. “The ATLAS Collaboration is made up of over 5000 worldwide members with diverse backgrounds, including 1200 PhD students and almost 3000 scientific authors,” says Andreas Hoecker, ATLAS Spokesperson. “It is through their efforts that the Collaboration has been able to fully exploit the potential of the ATLAS detector and bring these critical results to publication. Moreover, none of this would have been possible without the exceptional performance of the LHC and CERN’s accelerator complex, relying on the imagination and professionalism of highly trained accelerator physicists, engineers and technicians.”

One of the best-known ATLAS results is the discovery of the Higgs boson: the final missing piece of the Standard Model of particle physics. When ATLAS first began recording LHC collisions in 2009, the existence of the Higgs boson remained unknown – and with it the entire framework for giving mass to elementary particles was unconfirmed. The Higgs boson was finally discovered by the ATLAS and CMS Collaborations in 2012 and its study is now the subject of an entirely new field of particle-physics research. Not only are researchers making precise measurements of its properties and interactions, the Higgs boson is also a powerful tool in the search for new physics phenomena.

Such searches – be it for signs of Supersymmetry or new particles that may constitute dark matter – are another critical topic explored in ATLAS’ 1000 collision papers. Though no new phenomena have been observed so far, these searches have left a permanent mark on high-energy physics. They have shaped – and in some cases, shattered – the theoretical models that extend the description of fundamental matter and forces beyond our current incomplete (but experimentally confirmed) understanding. The sophisticated techniques devised to optimally separate tiny potential signals from abundant background processes have been applied far beyond their intended analyses.

Researchers have also been able to study key particle-physics processes never observed before, such as the direct scattering among the carriers of weak and electromagnetic forces. Many processes have furthermore been measured with much greater precision than anticipated at a proton collider. "Several results have surpassed the records set by previous ‘precision machines’, such as CERN’s Large Electron–Positron (LEP) collider,” says Stéphane Willocq, ATLAS Physics Coordinator. “As a ‘discovery machine’, the LHC collides composite particles, creating complex collision events that pose a challenge when making precision measurements. By applying innovative calibration techniques to their vast datasets, our researchers have been able to exceed expectations.”

Another area of ATLAS research that has seen great innovation is the heavy-ion physics programme, which explores a state of hot and dense matter called the quark-gluon plasma. “We have a small but prolific research community that has developed novel techniques for exploring heavy-nuclei collisions,” adds Stéphane. “Their work has illustrated the ways in which ‘general purpose’ detectors such as ATLAS can contribute to this specialised field of research. The 2010 discovery of jet quenching in central heavy-ion collisions and the 2019 observation of light scattering upon light in the extreme electric fields of peripheral heavy-ion collisions are only two of the highlights of this successful programme.”

While reaching this milestone number of papers is worth celebrating, it is the work behind these publications that deserves the spotlight. Each represents a step forward in our understanding of the Universe – look forward to another thousand steps over the decade to come, as the ATLAS Collaboration continues their exploration with the LHC, and prepares for its high-intensity second phase: the High-Luminosity LHC.

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