The ninth annual conference on Large Hadron Collider physics (LHCP 2021) begins today in video-conference rooms around the world.

Soon after the Big Bang, the Universe was too hot for normal matter to exist. Instead, it was made up of an extremely hot liquid of quarks and gluons: the quark-gluon plasma (QGP). In this live talk, Dr. Anne Marie Sickles explains how physicists at the ATLAS experiment are studying the QGP and what they've have learned.

On Friday 28 May 2021, teams of physicists and engineers installed the final "wedge" of the first ATLAS New Small Wheel detector. This was an important milestone for the Collaboration, in preparation for the wheel’s installation in the ATLAS cavern later this summer.

Making a scientific breakthrough in 2021 requires more than just a microscope – most scientists rely on powerful computers and ingenious software to carry out their research. In this live talk, Dr. James Catmore explains the advanced computing and software techniques used by the ATLAS Experiment.

On 13 April 2021, the recipients of this year's ATLAS PhD Grant were celebrated in an online ceremony. These talented and motivated students will receive 1.5 years of funding for their studies at CERN, giving them the opportunity to enhance their doctoral studies in a one-of-a-kind research environment.

John P. Rutherfoord is a professor at the University of Arizona and a long-standing member of the ATLAS Collaboration. His extensive career has taken him from searching for the Upsilon particle at Fermilab to CERN to leading the design and development of the ATLAS Forward Calorimeter. 

Since 2017, the ATLAS Early Career Scientist Board (ECSB) and Analysis Software Tutorial organisers have been teaming up to run a week-long introductory event for new ATLAS members. Induction Day welcomes new members to the collaboration by giving them an overview of the plethora of activities that take place within the ATLAS Collaboration.

The ATLAS Collaboration presented a host of brand-new results at Moriond spanning a broad range of subjects, from further tests of the Standard Model to searches for new phenomena motivated by as-yet unresolved mysteries of particle physics.

In a new result released this week, the ATLAS Collaboration studied the production of four top quarks at once in LHC collisions. This is the heaviest particle final state ever seen at the LHC, and provides physicists with a unique opportunity to study the top quark’s relationship to the Higgs boson.

A new result from the ATLAS Collaboration – debuted at the virtual Moriond Electroweak conference – sets itself apart from more traditional LHC searches. Typically, physicists will look for new particles produced in LHC collisions that immediately decay to known or invisible particles. This analysis, in contrast, looks for new particles that live for roughly a hundred nanoseconds or more before decaying.

The Higgs boson reveals its properties to the outside world twice: during production and decay. ATLAS’ new result studies the Higgs boson at both of these moments, looking at its production via two different methods and its subsequent decay into two W bosons.

Since 1966, Les Rencontres de Moriond has united experimentalists and theorists for weeks of scientific discussion. 2021 is no exception – but instead of in-person chats over coffee in La Thuile (Italy), physicists will be sharing their new findings in online meetings.

The special status of the top and bottom quarks makes them key players in the search for phenomena not foreseen by the Standard Model. New ATLAS results set strong constraints on the production of supersymmetric bottom quarks and of possible dark-matter particles. 

CERN’s Large Hadron Collider (LHC) is famous for colliding protons at world-record energies – but sometimes it pays to dial down the energy and see what happens under less extreme conditions.

In new results released this week, ATLAS physicists describe novel techniques used to accurately align the muon spectrometer.

The ATLAS Collaboration welcomes new management this month, with Andreas Hoecker (CERN) taking the lead as Spokesperson for the experiment.

At the ATLAS Early Career Scientist Board (ECSB), we have also had to adapt in order to best represent and assist the early career scientists in our collaboration. One of the biggest changes was moving all of our events in the second half of 2020 to be entirely virtual.

ATLAS PhD students are a key cohort of the Collaboration, making unique and crucial contributions to the experiment while working on their degree. Every year, their work is celebrated in the context of the ATLAS Thesis Awards.

The 2020 ATLAS Outstanding Achievement Awards ceremony was held online on 11 February 2021. Established in 2014, the awards recognise outstanding contributions in support of the ATLAS experiment, covering all areas except physics analysis. 

ATLAS finds first evidence of the Higgs boson decaying to two leptons and a photon. This is one of the rarest Higgs boson decays yet seen at the LHC, with striking features that presented unique challenges for the ATLAS experiment.

ATLAS PhD student Meirin Oan Evans explores how the University of Sussex is incorporating ATLAS Open Data into their teaching – and shares his experience using this incredible resource.

Despite the huge challenges of the COVID-19 pandemic, last year saw excellent successes for the ATLAS Collaboration, including first-of-a-kind physics results and great headway made on detector upgrades.

New results from the ATLAS Collaboration focus on different production modes of the Higgs boson decaying into b-quarks, capitalising on the power of machine learning to better discriminate this particular process from other proton collision events.

Journey into the ATLAS Experiment! On Thursday 26th November, Prof. Daniela Bortoletto gave a live public talk on Youtube describing how particle detectors like ATLAS find elementary particles.

The ATLAS Collaboration has just released a collection of 200 software packages that make up the Trigger and Data Acquisition System (TDAQ). With this new release, most ATLAS software is now open – reinforcing the Collaboration’s ongoing commitment to open science.