Gizmodo Science Fair: A Physics Experiment Turned Lead Into Gold

The ALICE Collaboration is a winner of the 2025 Gizmodo Science Fair for transforming lead into gold for a fraction of a second and exposing the strange physics that goes on inside the Large Hadron Collider.

The question

What byproducts does ALICE—the Large Ion Collider Experiment at CERN—produce when it studies matter at extreme energy levels?

The result

Many different things, but perhaps most interesting of all—gold!

In a Physical Review C paper published earlier this year, the ALICE Collaboration announced that between 2015 and 2018, the Large Hadron Collider (LHC) created around 86 billion gold nuclei, each lasting for about a microsecond.

ALICE primarily studies high-energy collisions between lead nuclei, whose charge is 82 times that of a proton. These large nuclei travel nearly at the speed of light in the Large Hadron Collider, which slams these particles into the ALICE detector. These collisions produce a pulse of photon energy that chips away bits of the nuclei—usually neutrons, but sometimes protons. When a lead nucleus loses three protons, it transmutes into element number 79, or gold.

This transmutation occurs around 50,000 to 80,000 times per second. Indeed, the program’s “gold production is quite copious,” said John Jowett, an accelerator physicist at CERN. “However, on a human scale the gold production is very small. [Until] now we’ve only created about, I think, 90 picograms, which is one millionth of a gram of gold.”

Those 90 picograms of gold disappear almost immediately after emerging, he added. “So this just reminds us—I like to say to people—how small atoms are compared to the scales we’re used to,” he said.

Why they did it

The result didn’t surprise any CERN scientist familiar with these instruments, Jowett said. “We didn’t talk about it much before, but we knew it should happen.”

Scientists were also aware that this process had serious implications for ALICE in general, according to Daniel Tapia Takaki, a physicist at the University of Kansas who led the CERN working groups for this project. Any particle that transmutes at CERN typically travels very long distances, meaning some inevitably smash into different sections of the LHC tunnel.

“So they basically become kind of a safety hazard—I mean, they at least start switching off the alarms,” said Tapia Takaki. “You want to have a collider that’s very stable… So understanding exactly how to mitigate this transmutation is one of the big priorities for the next generation of colliders.”

Uliana Dmitrieva is the ambitious young scientist who kicked off a project to officially record this process in a formal, scientific manner. The task proved so gargantuan that by the time the paper made headlines, Dmitrieva, who had proposed the project as a master’s student, had already finished her PhD and was preparing to become a staff scientist at Italy’s National Institute of Nuclear Physics.

“It took more time than my PhD thesis,” she laughed. “There were very few [formal] analyses of [these processes] , and actually, I had to do everything from scratch, because it was difficult to model. There were a lot of bugs in [the calculations] because nobody had checked this before.”

Why they’re a winner

All that strain proved more than worth the effort—but in ways the team never imagined. The public attention for this project somewhat disguises the fact that gold production is “just a small part of the paper; the paper was mostly about proton emission and lead collisions due to these so-called ultra-peripheral interactions,” Jowett noted.

“It was…strange, because, okay, we just measured protons—nothing interesting—why is it everywhere?” Dmitrieva joked. “It sounds really funny that there’s some kind of alchemy at the LHC.”

But the team decided to lean into this angle, which clearly “caught the imagination of the public, and we thought it was a nice way to explain some of this physics,” Jowett added. Overall, they were pleasantly surprised to see their project become an entry point to the grand scientific enterprise at CERN.

“It made us happy but also humbled,” Tapia Takaki said. “We have a responsibility to share the knowledge and the excitement—and certainly, [creating gold] is very exciting.”

What’s next

Now that the public excitement has cooled down, the researchers are looking to build on this data to further improve the detectors. That said, and given the large size of the project, there isn’t a single, consolidated plan for the collaboration as a whole.

Tapia Takaki wants to boost the collaboration’s ability to make precise, systematic measurements of proton and neutron emission. With these results, he hopes ALICE’s quirky particle physics can help tackle the most pressing questions in quantum mechanics.

Jowett, who retired in 2019, now advises younger physicists, including at the ALICE Collaboration. “There’s a lot of research going on at the LHC,” he said. “It’s a very broadband machine that studies many things—ALICE is just one part of it. This has given a few surprises. And I think it will continue to do so.”

The team

To say that ALICE is a big collaboration would be a tremendous understatement. With 1,886 members across 163 institutions in 39 countries, it takes a veritable city of scientists to turn lead into gold. A full list of ALICE Collaboration members can be found here.

Click here to see all of the winners of the 2025 Gizmodo Science Fair.