Scientists at CERN he pushed antimatter production into a new era, creating tens of thousands of antihydrogen atoms is no longer a decade-long dream but a routine overnight feat.
In a paper published today, researchers from CERN’s ALPHA experiment revealed a new cooling technique that lets them generate more than 15,000 antihydrogen atoms in just a few hours.
That’s a dramatic leap in efficiency for the simplest form of atomic antimatter, made of a positron orbiting an antiproton.
“These numbers would he been considered science fiction 10 years ago,” said Jeffrey Hangst, spokesperson for the ALPHA experiment.
“With larger numbers of antihydrogen atoms now more readily ailable, we can investigate atomic antimatter in greater detail and at a faster pace than before.”
To create antihydrogen, the team must first trap and cool clouds of positrons and antiprotons separately before merging them.
Over the years, this process has been steadily refined. But the latest breakthrough, an innovative way to cool positrons, has boosted the rate of antihydrogen production by a factor of eight.
The heart of the advance lies in how the positrons are prepared. The particles are first generated from a radioactive form of sodium and captured inside a Penning trap, where electromagnetic fields hold them in place.
Inside the trap, they naturally swirl, losing a bit of energy as they move. This self-cooling effect helps, but not nearly enough for efficient antihydrogen formation.
To overcome this limitation, the ALPHA team introduced a cloud of laser-cooled beryllium ions into the trap, allowing the positrons to shed energy through a process known as sympathetic cooling.
Cooling that transformsThis decision took the positron cloud to an astonishing temperature of about −266°C. At such low energies, the particles become far more likely to bind with antiprotons to form antihydrogen.
As a result, more than 15,000 antihydrogen atoms accumulated in under seven hours. For comparison, a previous experiment needed 10 weeks to collect around 16,000 atoms for a high-precision spectroscopy study.
“The new technique is a real game-changer when it comes to investigating systematic uncertainties in our measurements. We can now accumulate antihydrogen overnight and measure a spectral line the following day,” said Niels Madsen, deputy spokesperson for ALPHA and leader of the positron-cooling project.
Antimatter at scaleAcross the 2023–24 experimental runs, the method enabled the production of more than two million antihydrogen atoms, achieving the numbers researchers once thought impossible.
This year, the ALPHA collaboration is using this unprecedented supply to explore how grity affects antimatter under the ALPHA-g experiment, a key test of fundamental physics.
As sympathetic cooling continues to unlock larger datasets and faster measurements, scientists expect to probe antimatter’s properties with unmatched precision. And that could deepen our understanding of some of the most mysterious asymmetries in the universe.
The findings from the study he been published in the journal Nature Communications.
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