ATLAS Experiment

ATLAS 2025 Thesis Awards spotlight the “soul” of the Collaboration The 2025 ATLAS Thesis Award ceremony. From left to right: ATLAS Collaboration Board Chair Davide Constanzo; ATLAS Thesis Awards Committee Chair Jean-François Arguin; ATLAS Thesis Award winners Elena M...

The ATLAS Experiment Thesis Awards celebrate exceptional doctoral research and the vital contributions students make to #particlephysics.

Meet this year’s recipients, representing institutions across the global ATLAS community ⤵️
atlas.cern/Updates/News...

Deep into the detector 👷

Today’s #PhotoOfTheWeek features the @atlasexperiment.bsky.social detector during the year-end technical stop (YETS) – a brief winter switch-off that allows for essential maintenance and upgrades on equipment and detectors, preparing them for the following physics run.

Getting to the top of jet calibration When particles burst from an LHC collision, they rarely leave a simple, single trail for physicists to follow. More often, they are high-energy quarks and gluons that erupt into jets, collimated spray...

How do you measure a confetti cannon of particles? 🎉

Physicists at the ATLAS Experiment at @cern.bsky.social have pioneered a novel technique using top-quark decays to calibrate particle "jets" - the most common "footprints" left by #LHC collisions!

Learn more ⤵️ atlas.cern/Updates/Brie...

Here our scientists are testing the robotic handling of a vacuum module in the ATLAS cavern, part of the preparations for the operation of the High-Luminosity #LHC, the successor to CERN’s flagship accelerator.

ATLAS maps the top quark–Higgs boson interaction with multileptons One of the central questions in particle physics is how fundamental particles acquire mass. The top quark, as the heaviest known elementary particle, interacts most strongly with the Higgs boson. As s...

The top quark’s large mass means it interacts most strongly with the Higgs field. By studying its pair production alongside a Higgs boson – a process that accounts for just 1% of all Higgs – researchers are learning about the origin of particle masses. Learn more ⤵️ atlas.cern/Updates/Brie...

This year, for the #InternationalDayofWomenandGirlsinScience, we’re celebrating the “sparks” that ignite careers in physics. ⚛️⁠ ⁠ We asked four ATLAS experiment researchers to share what first inspired them. The stories of these women show that the spark for physics can come from anywhere! 👇

Transforming sensitivity to new physics with single-top-quark events The top quark, the heaviest known elementary particle, has captivated physicists since its discovery in the 1990s and holds a privileged place within the Standard Model of particle physics. It has a v...

Heavy, energetic and fast-decaying — the #topquark’s properties make it an incredible tool for searching for new particles at high energy. Using an ingenious new technique, ATLAS physicists at @cern.bsky.social are now exploring single-top collisions with high precision ⤵️ atlas.cern/Updates/Brie...

Pride flag in front of the ATLAS experiment.

Happy #PrideinSTEMDay! 🏳️‍🌈🏳️‍⚧️

ATLAS proudly celebrates the incredible diversity of our scientific community. Our varied backgrounds, perspectives and identities drive excellence in research. We are committed to advancing the recognition and representation of our LGBTQ+ colleagues — today and every day.

Heavy-ion season is here! 💥⁠
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The ATLAS Experiment at @cern.bsky.social has recorded its first lead-lead collisions of 2025, marking the start of three weeks of heavy-ion running at 5.36 TeV per nucleon pair.⁠ Take a look at some of our first spectacular event displays!⁠

🎤 Are you passionate about science? Show us! 😉

To mark the 20th anniversary of FameLab International, CERN is teaming up with FameLab to invite you to share your love for science and win fantastic prizes.

YouTube video by ATLAS Experiment Mapping the Secrets of the Universe | Inside the ATLAS Experiment

Curiosity drives discovery!🌌

The ATLAS Experiment @cern.bsky.social brings together thousands of scientists and engineers from around the world to explore the building blocks of the Universe.

🎥 Watch our new introductory video, available in 6 languages on YouTube. www.youtube.com/watch?v=6UqW...

Shining light on the Weak force: ATLAS observes WWγ production The ATLAS Collaboration reports its first observation of WWγ production – a rare process involving the simultaneous production of two W bosons and a photon. The weak force is one of the four fundament...

A rare sight at the LHC 👀

The ATLAS Collaboration at @cern.bsky.social reports its first observation of WWγ production — a rare process where two W bosons and a photon are produced together.

🔗 Learn more: atlas.cern/Updates/Brie...

Congratulations to ATLAS Physicist Mounia Laassiri (Brookhaven National Laboratory) on being named a laureate of the 2025 UNESCO–AI Fozan Prize for the Promotion of Young Scientists in STEM!

🔗 Learn more: www.unesco.org/en/articles/...

ATLAS takes a closer look at the all-charm tetraquark The strong force, unrivaled in strength yet confined to minuscule distances, produces unique bound states of quarks known as quarkonia. These are the strong-force equivalent of the hydrogen atom, cons...

Four charm quarks, one exotic state: the X(6900) tetraquark. The ATLAS Collaboration at @cern.bsky.social takes a deep dive into the all-charm tetraquark, marking a key step toward understanding exotic bound states of quarks. Learn more ⤵️ atlas.cern/Updates/Brie...

Turning the LHC into a Lepton-Proton Collider in the search for leptoquarks All matter in the universe is made up of just two fundamental building blocks: quarks and leptons. Intriguingly, both have three distinct families or “generations”. For example, the electron and its a...

What if we could turn the LHC into a lepton–proton collider? ✨

Thanks to rare quantum fluctuations, protons can briefly contain lepton–antilepton pairs. This allows ATLAS physicists to study lepton–proton collisions, opening a new door in the search for leptoquarks! ⤵️ atlas.cern/Updates/Brie...

Neon collides at the LHC! ✨

The ATLAS Experiment at @cern.bsky.social records its first-ever neon–neon collisions. Take a look at these striking collision event displays – then discover how neon opens up exciting new opportunities to explore the strong force! 🔗 atlas.cern/Updates/News...

Modern #AI techniques are unlocking new ways to analyse particle collisions – and ATLAS is embracing the possibilities.

🔗 Check out our new briefing to learn more ⤵️ atlas.cern/Updates/Brie...

ATLAS closes in on rare Higgs decays The ATLAS Collaboration finds evidence of Higgs-boson decays to muons and improves sensitivity to Higgs-boson decays to a Z boson and a photon. Since the discovery of the Higgs boson in 2012, physicis...

ATLAS closes in on two rare Higgs boson decays! 🤔🔎

New results based on 7 years of LHC data reveal evidence for the Higgs boson decaying to muons, and significantly enhance sensitivity to its decay into a Z boson and a photon.

🔗 Learn more ⤵️ atlas.cern/Updates/Brie...

Elusive romance of top-quark pairs observed at the LHC

The @cmsexperiment.bsky.social and @atlasexperiment.bsky.social at CERN’s Large Hadron Collider have observed an unforeseen feature in the behaviour of top quarks that suggests that they form a fleeting union

Bound to be discovered? ATLAS explores top-quark interactions near threshold The top quark is a bit of a loner. While other quarks can join together to form bound states called hadrons, the top quark’s extremely short lifetime means it decays almost instantly – disappearing be...

Bound to be discovered? 🌌

Physicists at the ATLAS Experiment at @cern.bsky.social have observed a "quasi-bound" state formed by a top quark and an anti-top quark – an interaction so subtle it was long thought undetectable at the #LHC.

🔗 Learn more ⤵️ atlas.cern/Updates/Brie...

ATLAS records its first-ever oxygen-oxygen collisions at the LHC! 🎇

These collisions offer a new way to explore the quark-gluon plasma in smaller systems — bridging the gap between proton-lead and lead-lead collisions. 🔗 Learn more: atlas.cern/Updates/News...

1️⃣ François Englert and Peter Higgs at the announcement

2️⃣ They weren’t alone — the auditorium was packed

3️⃣ Outside, the queue to get in

4️⃣ Journalists waiting for the press conference

13 years later… still a picture-perfect moment!📸
On 4 July 2012, ATLAS and @cmsexperiment.bsky.social announced the discovery of the Higgs boson! Today, we return to the places that witnessed history, because some stories are worth reliving.

The Higgs journey since 2012 👉️ atlas.cern/Discover/Phy...

This release simplifies and expands on previous ATLAS open data releases with a dedicated, open-source framework, now publicly available, alongside enhanced tools and documentation. It includes:
🗒️ Guided workbooks and code
💻️ Modules to build computing skills
🧑‍🏫 Support for educators

The ATLAS Collaboration at @cern.bsky.social has just launched a new release of #opendata designed to empower education, outreach and #citizenscience!

Explore the new release ⤵️
opendata.atlas.cern/docs/categor...

Protons and oxygen collide!💥

The ATLAS Experiment at @cern.bsky.social has recorded its first-ever proton–oxygen collisions. Breathe in today's stunning event displays, then learn how these light-ion collisions can deepen our understanding of fundamental forces. ➡️ atlas.cern/Updates/News...

Celebrating the outstanding achievements of the ATLAS Collaboration The ATLAS Collaboration celebrated the dedication, ingenuity and collaborative spirit of its members at the 8th Outstanding Achievement Awards. Winners of the ATLAS Outstanding Achievement Awards 2025...

The ATLAS Collaboration proudly celebrates the recipients of the 2025 ATLAS Outstanding Achievement Awards – recognising the essential, behind-the-scenes work that powers great physics.

Meet this recipients ⤵️ atlas.cern/Updates/News...

🎓 Studying particle physics? We've got you covered with expert-designed #cheatsheets from the ATLAS Collaboration!

From Feynman diagrams to Monte Carlo, these resources break down some of the most important concepts in particle physics.

🔗 Explore them all here: atlas.cern/Resources/Ch...

🎉 Congratulations to ATLAS Physicist Maria Teresa Dova (University of La Plata) on being named a laureate of the 2025 L’Oréal-UNESCO For Women in Science Awards!

🔗 Learn more: www.unesco.org/en/articles/...

Congratulations to ATLAS physicist Daniela Bortoletto of @ox.ac.uk on being named a 2024 Emmy Noether Distinction Laureate by the European Physical Society! 🎉

🔗 Learn more: eps.org/the-eps-emmy-noether-distinction-2024-is-announced

Here we see the @atlasexperiment.bsky.social Inner Tracker (ITk) Pixel Module assembly #AtCERN.

The ITk is a completely new, state-of-the-art detector that will replace the current innermost layer of ATLAS.