CERN physicist creates accurate 3D model of ATLAS experiment

What began as a joke among Jan Brajer, a CERN’s ATLAS Detector Operation group member, and his colleagues soon turned into a full-fledged passion project. Initially, they joked about having a small ATLAS model in their office to help explain the detector’s parts to those unfamiliar with its structure. Soon, Jan was officially tasked with creating one as a retirement gift for the ATLAS coordinator. Now, the 3D printable 3D model of the ATLAS experiment is available to download on MakerWorld.

He spent six months meticulously designing the 3D model, replicating ATLAS’s intricate structure. The process was not without challenges.

“The hardest part was probably creating the toroid structure while balancing printability and detail,” Jan explained. “However, getting physically on-site to measure some muon chambers was a close second.”

The final model consisted of over 200 parts and took five weeks to print and assemble, using four 3D printers.

“Assembly was a nightmare, and I noticed many areas for improvement in the model,” Jan recalled. “I was incredibly relieved when the model was delivered to its recipient, so I no longer had to think about it.”

However, the story didn’t end there. Multiple departments requested the model for educational and promotional purposes.

What is ATLAS?

The ATLAS detector is a massive scientific instrument at CERN, the European Organization for Nuclear Research. Founded in 1954 and located near Geneva, CERN houses the Large Hadron Collider (LHC), the world’s largest and most powerful particle accelerator. Scientists use it to study the universe’s fundamental building blocks and unlock its deepest mysteries.

Editor’s note: In 2006, I had the incredible opportunity to do a reportage on CERN and visit ATLAS, which is located in a 20-meter-tall artificial cave about 100 meters below ground. I was shown around by Fabiola Gianotti, who was then the director of the ATLAS experiment and later became the director of CERN. In 2006, the ATLAS experiment was still being set up, along with a massive overhaul of the accelerator ring (the LHC), which would lead to the discovery of the Higgs boson. Fabiola Gianotti patiently and clearly described how CERN was unraveling the mysteries of the universe and how this has led to multiple discoveries in everyday technology. Since then, I have had a fascination with the use of additive manufacturing at CERN and have reported about it in several articles

ATLAS is the largest particle detector ever built, measuring 46 x 25 x 25 meters and weighing between 7,000 and 9,000 tons. In perspective, ATLAS is as tall as an eight-story building, as long as half a football field, and as heavy as 1,200 elephants.

It functions like an advanced camera, capturing and analyzing high-energy particle collisions produced by the LHC. These collisions recreate conditions similar to those just after the Big Bang, providing scientists with insights into the universe’s origins. The detector records the results in extreme detail, helping researchers study phenomena such as the Higgs boson—a particle that explains how everything in the universe gains mass—and the elusive dark matter that makes up most of the cosmos. A new upgrade of the LHC, the High Luminosity LHC project, is expected to lead to discoveries when it becomes operational starting in 2028.

From passion project to public access

Being a perfectionist, Jan wanted to rework and simplify the model before sharing it with the public. He dedicated countless hours to refining the design. His improvements included merging specific muon structures to facilitate assembly and adapting barrel muon chambers for better printability. This made the model easier to reproduce while maintaining its intricate details.

Jan’s 1:100-scale ATLAS model is now available on MakerWorld and won second place in a Physics Education contest. It represents months of design work, countless iterations, and an extraordinary level of commitment.

For those who’d like to take a stab at it, this ambitious 3D printing project requires four days and six hours of print time, 2 kg of filament, and 644 magnets (plus glue) for assembly.